From: Jason Xing <[email protected]>
Originally, ixgbe driver doesn't allow the mounting of xdpdrv if the
server is equipped with more than 64 cpus online. So it turns out that
the loading of xdpdrv causes the "NOMEM" failure.
Actually, we can adjust the algorithm and then make it work through
mapping the current cpu to some xdp ring with the protect of @tx_lock.
Here're some numbers before/after applying this patch with xdp-example
loaded on the eth0X:
As client (tx path):
Before After
TCP_STREAM send-64 734.14 714.20
TCP_STREAM send-128 1401.91 1395.05
TCP_STREAM send-512 5311.67 5292.84
TCP_STREAM send-1k 9277.40 9356.22 (not stable)
TCP_RR send-1 22559.75 21844.22
TCP_RR send-128 23169.54 22725.13
TCP_RR send-512 21670.91 21412.56
As server (rx path):
Before After
TCP_STREAM send-64 1416.49 1383.12
TCP_STREAM send-128 3141.49 3055.50
TCP_STREAM send-512 9488.73 9487.44
TCP_STREAM send-1k 9491.17 9356.22 (not stable)
TCP_RR send-1 23617.74 23601.60
...
Notice: the TCP_RR mode is unstable as the official document explaines.
I tested many times with different parameters combined through netperf.
Though the result is not that accurate, I cannot see much influence on
this patch. The static key is places on the hot path, but it actually
shouldn't cause a huge regression theoretically.
Fixes: 33fdc82f08 ("ixgbe: add support for XDP_TX action")
Reported-by: kernel test robot <[email protected]>
Co-developed-by: Shujin Li <[email protected]>
Signed-off-by: Shujin Li <[email protected]>
Signed-off-by: Jason Xing <[email protected]>
---
v6:
- Move the declaration of static-key to the proper position (Test Robot)
- Add reported-by tag (Jason)
- Add more detailed performance test results (Jason)
v5:
- Change back to nr_cpu_ids (Eric)
v4:
- Update the wrong commit messages. (Jason)
v3:
- Change nr_cpu_ids to num_online_cpus() (Maciej)
- Rename MAX_XDP_QUEUES to IXGBE_MAX_XDP_QS (Maciej)
- Rename ixgbe_determine_xdp_cpu() to ixgbe_determine_xdp_q_idx() (Maciej)
- Wrap ixgbe_xdp_ring_update_tail() with lock into one function (Maciej)
v2:
- Adjust cpu id in ixgbe_xdp_xmit(). (Jesper)
- Add a fallback path. (Maciej)
- Adjust other parts related to xdp ring.
---
drivers/net/ethernet/intel/ixgbe/ixgbe.h | 15 ++++-
drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c | 9 ++-
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 64 ++++++++++++++++------
.../net/ethernet/intel/ixgbe/ixgbe_txrx_common.h | 1 +
drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 9 +--
5 files changed, 73 insertions(+), 25 deletions(-)
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
index a604552..1dcddea 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
@@ -351,6 +351,7 @@ struct ixgbe_ring {
};
u16 rx_offset;
struct xdp_rxq_info xdp_rxq;
+ spinlock_t tx_lock; /* used in XDP mode */
struct xsk_buff_pool *xsk_pool;
u16 ring_idx; /* {rx,tx,xdp}_ring back reference idx */
u16 rx_buf_len;
@@ -375,11 +376,13 @@ enum ixgbe_ring_f_enum {
#define IXGBE_MAX_FCOE_INDICES 8
#define MAX_RX_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
#define MAX_TX_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
-#define MAX_XDP_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
+#define IXGBE_MAX_XDP_QS (IXGBE_MAX_FDIR_INDICES + 1)
#define IXGBE_MAX_L2A_QUEUES 4
#define IXGBE_BAD_L2A_QUEUE 3
#define IXGBE_MAX_MACVLANS 63
+DECLARE_STATIC_KEY_FALSE(ixgbe_xdp_locking_key);
+
struct ixgbe_ring_feature {
u16 limit; /* upper limit on feature indices */
u16 indices; /* current value of indices */
@@ -629,7 +632,7 @@ struct ixgbe_adapter {
/* XDP */
int num_xdp_queues;
- struct ixgbe_ring *xdp_ring[MAX_XDP_QUEUES];
+ struct ixgbe_ring *xdp_ring[IXGBE_MAX_XDP_QS];
unsigned long *af_xdp_zc_qps; /* tracks AF_XDP ZC enabled rings */
/* TX */
@@ -772,6 +775,14 @@ struct ixgbe_adapter {
#endif /* CONFIG_IXGBE_IPSEC */
};
+static inline int ixgbe_determine_xdp_q_idx(int cpu)
+{
+ if (static_key_enabled(&ixgbe_xdp_locking_key))
+ return cpu % IXGBE_MAX_XDP_QS;
+ else
+ return cpu;
+}
+
static inline u8 ixgbe_max_rss_indices(struct ixgbe_adapter *adapter)
{
switch (adapter->hw.mac.type) {
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
index 0218f6c..86b1116 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
@@ -299,7 +299,10 @@ static void ixgbe_cache_ring_register(struct ixgbe_adapter *adapter)
static int ixgbe_xdp_queues(struct ixgbe_adapter *adapter)
{
- return adapter->xdp_prog ? nr_cpu_ids : 0;
+ int queues;
+
+ queues = min_t(int, IXGBE_MAX_XDP_QS, nr_cpu_ids);
+ return adapter->xdp_prog ? queues : 0;
}
#define IXGBE_RSS_64Q_MASK 0x3F
@@ -947,6 +950,7 @@ static int ixgbe_alloc_q_vector(struct ixgbe_adapter *adapter,
ring->count = adapter->tx_ring_count;
ring->queue_index = xdp_idx;
set_ring_xdp(ring);
+ spin_lock_init(&ring->tx_lock);
/* assign ring to adapter */
WRITE_ONCE(adapter->xdp_ring[xdp_idx], ring);
@@ -1032,6 +1036,9 @@ static void ixgbe_free_q_vector(struct ixgbe_adapter *adapter, int v_idx)
adapter->q_vector[v_idx] = NULL;
__netif_napi_del(&q_vector->napi);
+ if (static_key_enabled(&ixgbe_xdp_locking_key))
+ static_branch_dec(&ixgbe_xdp_locking_key);
+
/*
* after a call to __netif_napi_del() napi may still be used and
* ixgbe_get_stats64() might access the rings on this vector,
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 14aea40..bec29f5 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -165,6 +165,9 @@ static int ixgbe_notify_dca(struct notifier_block *, unsigned long event,
MODULE_DESCRIPTION("Intel(R) 10 Gigabit PCI Express Network Driver");
MODULE_LICENSE("GPL v2");
+DEFINE_STATIC_KEY_FALSE(ixgbe_xdp_locking_key);
+EXPORT_SYMBOL(ixgbe_xdp_locking_key);
+
static struct workqueue_struct *ixgbe_wq;
static bool ixgbe_check_cfg_remove(struct ixgbe_hw *hw, struct pci_dev *pdev);
@@ -2422,13 +2425,10 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
xdp_do_flush_map();
if (xdp_xmit & IXGBE_XDP_TX) {
- struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
+ int index = ixgbe_determine_xdp_q_idx(smp_processor_id());
+ struct ixgbe_ring *ring = adapter->xdp_ring[index];
- /* Force memory writes to complete before letting h/w
- * know there are new descriptors to fetch.
- */
- wmb();
- writel(ring->next_to_use, ring->tail);
+ ixgbe_xdp_ring_update_tail_locked(ring);
}
u64_stats_update_begin(&rx_ring->syncp);
@@ -6320,7 +6320,7 @@ static int ixgbe_sw_init(struct ixgbe_adapter *adapter,
if (ixgbe_init_rss_key(adapter))
return -ENOMEM;
- adapter->af_xdp_zc_qps = bitmap_zalloc(MAX_XDP_QUEUES, GFP_KERNEL);
+ adapter->af_xdp_zc_qps = bitmap_zalloc(IXGBE_MAX_XDP_QS, GFP_KERNEL);
if (!adapter->af_xdp_zc_qps)
return -ENOMEM;
@@ -8539,21 +8539,32 @@ static u16 ixgbe_select_queue(struct net_device *dev, struct sk_buff *skb,
int ixgbe_xmit_xdp_ring(struct ixgbe_adapter *adapter,
struct xdp_frame *xdpf)
{
- struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
struct ixgbe_tx_buffer *tx_buffer;
union ixgbe_adv_tx_desc *tx_desc;
+ struct ixgbe_ring *ring;
u32 len, cmd_type;
dma_addr_t dma;
+ int index, ret;
u16 i;
len = xdpf->len;
- if (unlikely(!ixgbe_desc_unused(ring)))
- return IXGBE_XDP_CONSUMED;
+ index = ixgbe_determine_xdp_q_idx(smp_processor_id());
+ ring = adapter->xdp_ring[index];
+
+ if (static_branch_unlikely(&ixgbe_xdp_locking_key))
+ spin_lock(&ring->tx_lock);
+
+ if (unlikely(!ixgbe_desc_unused(ring))) {
+ ret = IXGBE_XDP_CONSUMED;
+ goto out;
+ }
dma = dma_map_single(ring->dev, xdpf->data, len, DMA_TO_DEVICE);
- if (dma_mapping_error(ring->dev, dma))
- return IXGBE_XDP_CONSUMED;
+ if (dma_mapping_error(ring->dev, dma)) {
+ ret = IXGBE_XDP_CONSUMED;
+ goto out;
+ }
/* record the location of the first descriptor for this packet */
tx_buffer = &ring->tx_buffer_info[ring->next_to_use];
@@ -8590,7 +8601,11 @@ int ixgbe_xmit_xdp_ring(struct ixgbe_adapter *adapter,
tx_buffer->next_to_watch = tx_desc;
ring->next_to_use = i;
- return IXGBE_XDP_TX;
+ ret = IXGBE_XDP_TX;
+out:
+ if (static_branch_unlikely(&ixgbe_xdp_locking_key))
+ spin_unlock(&ring->tx_lock);
+ return ret;
}
netdev_tx_t ixgbe_xmit_frame_ring(struct sk_buff *skb,
@@ -10130,8 +10145,13 @@ static int ixgbe_xdp_setup(struct net_device *dev, struct bpf_prog *prog)
return -EINVAL;
}
- if (nr_cpu_ids > MAX_XDP_QUEUES)
+ /* if the number of cpus is much larger than the maximum of queues,
+ * we should stop it and then return with NOMEM like before.
+ */
+ if (nr_cpu_ids > IXGBE_MAX_XDP_QS * 2)
return -ENOMEM;
+ else if (nr_cpu_ids > IXGBE_MAX_XDP_QS)
+ static_branch_inc(&ixgbe_xdp_locking_key);
old_prog = xchg(&adapter->xdp_prog, prog);
need_reset = (!!prog != !!old_prog);
@@ -10195,12 +10215,22 @@ void ixgbe_xdp_ring_update_tail(struct ixgbe_ring *ring)
writel(ring->next_to_use, ring->tail);
}
+void ixgbe_xdp_ring_update_tail_locked(struct ixgbe_ring *ring)
+{
+ if (static_branch_unlikely(&ixgbe_xdp_locking_key))
+ spin_lock(&ring->tx_lock);
+ ixgbe_xdp_ring_update_tail(ring);
+ if (static_branch_unlikely(&ixgbe_xdp_locking_key))
+ spin_unlock(&ring->tx_lock);
+}
+
static int ixgbe_xdp_xmit(struct net_device *dev, int n,
struct xdp_frame **frames, u32 flags)
{
struct ixgbe_adapter *adapter = netdev_priv(dev);
struct ixgbe_ring *ring;
int nxmit = 0;
+ int index;
int i;
if (unlikely(test_bit(__IXGBE_DOWN, &adapter->state)))
@@ -10209,10 +10239,12 @@ static int ixgbe_xdp_xmit(struct net_device *dev, int n,
if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
return -EINVAL;
+ index = ixgbe_determine_xdp_q_idx(smp_processor_id());
+
/* During program transitions its possible adapter->xdp_prog is assigned
* but ring has not been configured yet. In this case simply abort xmit.
*/
- ring = adapter->xdp_prog ? adapter->xdp_ring[smp_processor_id()] : NULL;
+ ring = adapter->xdp_prog ? adapter->xdp_ring[index] : NULL;
if (unlikely(!ring))
return -ENXIO;
@@ -10230,7 +10262,7 @@ static int ixgbe_xdp_xmit(struct net_device *dev, int n,
}
if (unlikely(flags & XDP_XMIT_FLUSH))
- ixgbe_xdp_ring_update_tail(ring);
+ ixgbe_xdp_ring_update_tail_locked(ring);
return nxmit;
}
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h b/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
index 2aeec78..f6426d9 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
@@ -23,6 +23,7 @@ void ixgbe_process_skb_fields(struct ixgbe_ring *rx_ring,
void ixgbe_rx_skb(struct ixgbe_q_vector *q_vector,
struct sk_buff *skb);
void ixgbe_xdp_ring_update_tail(struct ixgbe_ring *ring);
+void ixgbe_xdp_ring_update_tail_locked(struct ixgbe_ring *ring);
void ixgbe_irq_rearm_queues(struct ixgbe_adapter *adapter, u64 qmask);
void ixgbe_txrx_ring_disable(struct ixgbe_adapter *adapter, int ring);
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
index b1d22e4..82d00e4 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
@@ -334,13 +334,10 @@ int ixgbe_clean_rx_irq_zc(struct ixgbe_q_vector *q_vector,
xdp_do_flush_map();
if (xdp_xmit & IXGBE_XDP_TX) {
- struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
+ int index = ixgbe_determine_xdp_q_idx(smp_processor_id());
+ struct ixgbe_ring *ring = adapter->xdp_ring[index];
- /* Force memory writes to complete before letting h/w
- * know there are new descriptors to fetch.
- */
- wmb();
- writel(ring->next_to_use, ring->tail);
+ ixgbe_xdp_ring_update_tail_locked(ring);
}
u64_stats_update_begin(&rx_ring->syncp);
--
1.8.3.1
On 8/31/21 9:49 PM, [email protected] wrote:
> From: Jason Xing <[email protected]>
>
> Originally, ixgbe driver doesn't allow the mounting of xdpdrv if the
> server is equipped with more than 64 cpus online. So it turns out that
> the loading of xdpdrv causes the "NOMEM" failure.
>
> Actually, we can adjust the algorithm and then make it work through
> mapping the current cpu to some xdp ring with the protect of @tx_lock.
>
> Here're some numbers before/after applying this patch with xdp-example
> loaded on the eth0X:
>
> As client (tx path):
> Before After
> TCP_STREAM send-64 734.14 714.20
> TCP_STREAM send-128 1401.91 1395.05
> TCP_STREAM send-512 5311.67 5292.84
> TCP_STREAM send-1k 9277.40 9356.22 (not stable)
> TCP_RR send-1 22559.75 21844.22
> TCP_RR send-128 23169.54 22725.13
> TCP_RR send-512 21670.91 21412.56
>
> As server (rx path):
> Before After
> TCP_STREAM send-64 1416.49 1383.12
> TCP_STREAM send-128 3141.49 3055.50
> TCP_STREAM send-512 9488.73 9487.44
> TCP_STREAM send-1k 9491.17 9356.22 (not stable)
> TCP_RR send-1 23617.74 23601.60
> ...
>
> Notice: the TCP_RR mode is unstable as the official document explaines.
>
> I tested many times with different parameters combined through netperf.
> Though the result is not that accurate, I cannot see much influence on
> this patch. The static key is places on the hot path, but it actually
> shouldn't cause a huge regression theoretically.
>
> Fixes: 33fdc82f08 ("ixgbe: add support for XDP_TX action")
> Reported-by: kernel test robot <[email protected]>
> Co-developed-by: Shujin Li <[email protected]>
> Signed-off-by: Shujin Li <[email protected]>
> Signed-off-by: Jason Xing <[email protected]>
> ---
> v6:
> - Move the declaration of static-key to the proper position (Test Robot)
> - Add reported-by tag (Jason)
> - Add more detailed performance test results (Jason)
>
> v5:
> - Change back to nr_cpu_ids (Eric)
>
> v4:
> - Update the wrong commit messages. (Jason)
>
> v3:
> - Change nr_cpu_ids to num_online_cpus() (Maciej)
> - Rename MAX_XDP_QUEUES to IXGBE_MAX_XDP_QS (Maciej)
> - Rename ixgbe_determine_xdp_cpu() to ixgbe_determine_xdp_q_idx() (Maciej)
> - Wrap ixgbe_xdp_ring_update_tail() with lock into one function (Maciej)
>
> v2:
> - Adjust cpu id in ixgbe_xdp_xmit(). (Jesper)
> - Add a fallback path. (Maciej)
> - Adjust other parts related to xdp ring.
> ---
> drivers/net/ethernet/intel/ixgbe/ixgbe.h | 15 ++++-
> drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c | 9 ++-
> drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 64 ++++++++++++++++------
> .../net/ethernet/intel/ixgbe/ixgbe_txrx_common.h | 1 +
> drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 9 +--
> 5 files changed, 73 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
> index a604552..1dcddea 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
> @@ -351,6 +351,7 @@ struct ixgbe_ring {
> };
> u16 rx_offset;
> struct xdp_rxq_info xdp_rxq;
> + spinlock_t tx_lock; /* used in XDP mode */
> struct xsk_buff_pool *xsk_pool;
> u16 ring_idx; /* {rx,tx,xdp}_ring back reference idx */
> u16 rx_buf_len;
> @@ -375,11 +376,13 @@ enum ixgbe_ring_f_enum {
> #define IXGBE_MAX_FCOE_INDICES 8
> #define MAX_RX_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
> #define MAX_TX_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
> -#define MAX_XDP_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
> +#define IXGBE_MAX_XDP_QS (IXGBE_MAX_FDIR_INDICES + 1)
> #define IXGBE_MAX_L2A_QUEUES 4
> #define IXGBE_BAD_L2A_QUEUE 3
> #define IXGBE_MAX_MACVLANS 63
>
> +DECLARE_STATIC_KEY_FALSE(ixgbe_xdp_locking_key);
> +
> struct ixgbe_ring_feature {
> u16 limit; /* upper limit on feature indices */
> u16 indices; /* current value of indices */
> @@ -629,7 +632,7 @@ struct ixgbe_adapter {
>
> /* XDP */
> int num_xdp_queues;
> - struct ixgbe_ring *xdp_ring[MAX_XDP_QUEUES];
> + struct ixgbe_ring *xdp_ring[IXGBE_MAX_XDP_QS];
> unsigned long *af_xdp_zc_qps; /* tracks AF_XDP ZC enabled rings */
>
> /* TX */
> @@ -772,6 +775,14 @@ struct ixgbe_adapter {
> #endif /* CONFIG_IXGBE_IPSEC */
> };
>
> +static inline int ixgbe_determine_xdp_q_idx(int cpu)
> +{
> + if (static_key_enabled(&ixgbe_xdp_locking_key))
> + return cpu % IXGBE_MAX_XDP_QS;
> + else
> + return cpu;
> +}
> +
> static inline u8 ixgbe_max_rss_indices(struct ixgbe_adapter *adapter)
> {
> switch (adapter->hw.mac.type) {
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
> index 0218f6c..86b1116 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
> @@ -299,7 +299,10 @@ static void ixgbe_cache_ring_register(struct ixgbe_adapter *adapter)
>
> static int ixgbe_xdp_queues(struct ixgbe_adapter *adapter)
> {
> - return adapter->xdp_prog ? nr_cpu_ids : 0;
> + int queues;
> +
> + queues = min_t(int, IXGBE_MAX_XDP_QS, nr_cpu_ids);
> + return adapter->xdp_prog ? queues : 0;
> }
>
> #define IXGBE_RSS_64Q_MASK 0x3F
> @@ -947,6 +950,7 @@ static int ixgbe_alloc_q_vector(struct ixgbe_adapter *adapter,
> ring->count = adapter->tx_ring_count;
> ring->queue_index = xdp_idx;
> set_ring_xdp(ring);
> + spin_lock_init(&ring->tx_lock);
>
> /* assign ring to adapter */
> WRITE_ONCE(adapter->xdp_ring[xdp_idx], ring);
> @@ -1032,6 +1036,9 @@ static void ixgbe_free_q_vector(struct ixgbe_adapter *adapter, int v_idx)
> adapter->q_vector[v_idx] = NULL;
> __netif_napi_del(&q_vector->napi);
>
> + if (static_key_enabled(&ixgbe_xdp_locking_key))
> + static_branch_dec(&ixgbe_xdp_locking_key);
> +
> /*
> * after a call to __netif_napi_del() napi may still be used and
> * ixgbe_get_stats64() might access the rings on this vector,
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> index 14aea40..bec29f5 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> @@ -165,6 +165,9 @@ static int ixgbe_notify_dca(struct notifier_block *, unsigned long event,
> MODULE_DESCRIPTION("Intel(R) 10 Gigabit PCI Express Network Driver");
> MODULE_LICENSE("GPL v2");
>
> +DEFINE_STATIC_KEY_FALSE(ixgbe_xdp_locking_key);
> +EXPORT_SYMBOL(ixgbe_xdp_locking_key);
> +
> static struct workqueue_struct *ixgbe_wq;
>
> static bool ixgbe_check_cfg_remove(struct ixgbe_hw *hw, struct pci_dev *pdev);
> @@ -2422,13 +2425,10 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
> xdp_do_flush_map();
>
> if (xdp_xmit & IXGBE_XDP_TX) {
> - struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
> + int index = ixgbe_determine_xdp_q_idx(smp_processor_id());
> + struct ixgbe_ring *ring = adapter->xdp_ring[index];
>
> - /* Force memory writes to complete before letting h/w
> - * know there are new descriptors to fetch.
> - */
> - wmb();
> - writel(ring->next_to_use, ring->tail);
> + ixgbe_xdp_ring_update_tail_locked(ring);
> }
>
> u64_stats_update_begin(&rx_ring->syncp);
> @@ -6320,7 +6320,7 @@ static int ixgbe_sw_init(struct ixgbe_adapter *adapter,
> if (ixgbe_init_rss_key(adapter))
> return -ENOMEM;
>
> - adapter->af_xdp_zc_qps = bitmap_zalloc(MAX_XDP_QUEUES, GFP_KERNEL);
> + adapter->af_xdp_zc_qps = bitmap_zalloc(IXGBE_MAX_XDP_QS, GFP_KERNEL);
> if (!adapter->af_xdp_zc_qps)
> return -ENOMEM;
>
> @@ -8539,21 +8539,32 @@ static u16 ixgbe_select_queue(struct net_device *dev, struct sk_buff *skb,
> int ixgbe_xmit_xdp_ring(struct ixgbe_adapter *adapter,
> struct xdp_frame *xdpf)
> {
> - struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
> struct ixgbe_tx_buffer *tx_buffer;
> union ixgbe_adv_tx_desc *tx_desc;
> + struct ixgbe_ring *ring;
> u32 len, cmd_type;
> dma_addr_t dma;
> + int index, ret;
> u16 i;
>
> len = xdpf->len;
>
> - if (unlikely(!ixgbe_desc_unused(ring)))
> - return IXGBE_XDP_CONSUMED;
> + index = ixgbe_determine_xdp_q_idx(smp_processor_id());
> + ring = adapter->xdp_ring[index];
> +
> + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> + spin_lock(&ring->tx_lock);
> +
> + if (unlikely(!ixgbe_desc_unused(ring))) {
> + ret = IXGBE_XDP_CONSUMED;
> + goto out;
> + }
>
> dma = dma_map_single(ring->dev, xdpf->data, len, DMA_TO_DEVICE);
> - if (dma_mapping_error(ring->dev, dma))
> - return IXGBE_XDP_CONSUMED;
> + if (dma_mapping_error(ring->dev, dma)) {
> + ret = IXGBE_XDP_CONSUMED;
> + goto out;
> + }
>
> /* record the location of the first descriptor for this packet */
> tx_buffer = &ring->tx_buffer_info[ring->next_to_use];
> @@ -8590,7 +8601,11 @@ int ixgbe_xmit_xdp_ring(struct ixgbe_adapter *adapter,
> tx_buffer->next_to_watch = tx_desc;
> ring->next_to_use = i;
>
> - return IXGBE_XDP_TX;
> + ret = IXGBE_XDP_TX;
> +out:
> + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> + spin_unlock(&ring->tx_lock);
> + return ret;
> }
>
> netdev_tx_t ixgbe_xmit_frame_ring(struct sk_buff *skb,
> @@ -10130,8 +10145,13 @@ static int ixgbe_xdp_setup(struct net_device *dev, struct bpf_prog *prog)
> return -EINVAL;
> }
>
> - if (nr_cpu_ids > MAX_XDP_QUEUES)
> + /* if the number of cpus is much larger than the maximum of queues,
> + * we should stop it and then return with NOMEM like before.
> + */
> + if (nr_cpu_ids > IXGBE_MAX_XDP_QS * 2)
> return -ENOMEM;
> + else if (nr_cpu_ids > IXGBE_MAX_XDP_QS)
> + static_branch_inc(&ixgbe_xdp_locking_key);
>
> old_prog = xchg(&adapter->xdp_prog, prog);
> need_reset = (!!prog != !!old_prog);
> @@ -10195,12 +10215,22 @@ void ixgbe_xdp_ring_update_tail(struct ixgbe_ring *ring)
> writel(ring->next_to_use, ring->tail);
> }
>
> +void ixgbe_xdp_ring_update_tail_locked(struct ixgbe_ring *ring)
> +{
> + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> + spin_lock(&ring->tx_lock);
> + ixgbe_xdp_ring_update_tail(ring);
> + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> + spin_unlock(&ring->tx_lock);
> +}
It is not clear why you use a pair of spin_lock()/unlock for each ixgbe_xmit_xdp_ring()
call, plus one other for ixgbe_xdp_ring_update_tail()
I guess this could be factorized to a single spin lock/unlock in ixgbe_xdp_xmit(),
and thus not have this ixgbe_xdp_ring_update_tail_locked() helper ?
> +
> static int ixgbe_xdp_xmit(struct net_device *dev, int n,
> struct xdp_frame **frames, u32 flags)
> {
> struct ixgbe_adapter *adapter = netdev_priv(dev);
> struct ixgbe_ring *ring;
> int nxmit = 0;
> + int index;
> int i;
>
> if (unlikely(test_bit(__IXGBE_DOWN, &adapter->state)))
> @@ -10209,10 +10239,12 @@ static int ixgbe_xdp_xmit(struct net_device *dev, int n,
> if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
> return -EINVAL;
>
> + index = ixgbe_determine_xdp_q_idx(smp_processor_id());
> +
> /* During program transitions its possible adapter->xdp_prog is assigned
> * but ring has not been configured yet. In this case simply abort xmit.
> */
> - ring = adapter->xdp_prog ? adapter->xdp_ring[smp_processor_id()] : NULL;
> + ring = adapter->xdp_prog ? adapter->xdp_ring[index] : NULL;
> if (unlikely(!ring))
> return -ENXIO;
>
> @@ -10230,7 +10262,7 @@ static int ixgbe_xdp_xmit(struct net_device *dev, int n,
> }
>
> if (unlikely(flags & XDP_XMIT_FLUSH))
> - ixgbe_xdp_ring_update_tail(ring);
> + ixgbe_xdp_ring_update_tail_locked(ring);
>
> return nxmit;
> }
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h b/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
> index 2aeec78..f6426d9 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
> @@ -23,6 +23,7 @@ void ixgbe_process_skb_fields(struct ixgbe_ring *rx_ring,
> void ixgbe_rx_skb(struct ixgbe_q_vector *q_vector,
> struct sk_buff *skb);
> void ixgbe_xdp_ring_update_tail(struct ixgbe_ring *ring);
> +void ixgbe_xdp_ring_update_tail_locked(struct ixgbe_ring *ring);
> void ixgbe_irq_rearm_queues(struct ixgbe_adapter *adapter, u64 qmask);
>
> void ixgbe_txrx_ring_disable(struct ixgbe_adapter *adapter, int ring);
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
> index b1d22e4..82d00e4 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
> @@ -334,13 +334,10 @@ int ixgbe_clean_rx_irq_zc(struct ixgbe_q_vector *q_vector,
> xdp_do_flush_map();
>
> if (xdp_xmit & IXGBE_XDP_TX) {
> - struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
> + int index = ixgbe_determine_xdp_q_idx(smp_processor_id());
> + struct ixgbe_ring *ring = adapter->xdp_ring[index];
>
> - /* Force memory writes to complete before letting h/w
> - * know there are new descriptors to fetch.
> - */
> - wmb();
> - writel(ring->next_to_use, ring->tail);
> + ixgbe_xdp_ring_update_tail_locked(ring);
> }
>
> u64_stats_update_begin(&rx_ring->syncp);
>
On Wed, Sep 1, 2021 at 1:13 PM Eric Dumazet <[email protected]> wrote:
>
>
>
> On 8/31/21 9:49 PM, [email protected] wrote:
> > From: Jason Xing <[email protected]>
> >
> > Originally, ixgbe driver doesn't allow the mounting of xdpdrv if the
> > server is equipped with more than 64 cpus online. So it turns out that
> > the loading of xdpdrv causes the "NOMEM" failure.
> >
> > Actually, we can adjust the algorithm and then make it work through
> > mapping the current cpu to some xdp ring with the protect of @tx_lock.
> >
> > Here're some numbers before/after applying this patch with xdp-example
> > loaded on the eth0X:
> >
> > As client (tx path):
> > Before After
> > TCP_STREAM send-64 734.14 714.20
> > TCP_STREAM send-128 1401.91 1395.05
> > TCP_STREAM send-512 5311.67 5292.84
> > TCP_STREAM send-1k 9277.40 9356.22 (not stable)
> > TCP_RR send-1 22559.75 21844.22
> > TCP_RR send-128 23169.54 22725.13
> > TCP_RR send-512 21670.91 21412.56
> >
> > As server (rx path):
> > Before After
> > TCP_STREAM send-64 1416.49 1383.12
> > TCP_STREAM send-128 3141.49 3055.50
> > TCP_STREAM send-512 9488.73 9487.44
> > TCP_STREAM send-1k 9491.17 9356.22 (not stable)
> > TCP_RR send-1 23617.74 23601.60
> > ...
> >
> > Notice: the TCP_RR mode is unstable as the official document explaines.
> >
> > I tested many times with different parameters combined through netperf.
> > Though the result is not that accurate, I cannot see much influence on
> > this patch. The static key is places on the hot path, but it actually
> > shouldn't cause a huge regression theoretically.
> >
> > Fixes: 33fdc82f08 ("ixgbe: add support for XDP_TX action")
> > Reported-by: kernel test robot <[email protected]>
> > Co-developed-by: Shujin Li <[email protected]>
> > Signed-off-by: Shujin Li <[email protected]>
> > Signed-off-by: Jason Xing <[email protected]>
> > ---
> > v6:
> > - Move the declaration of static-key to the proper position (Test Robot)
> > - Add reported-by tag (Jason)
> > - Add more detailed performance test results (Jason)
> >
> > v5:
> > - Change back to nr_cpu_ids (Eric)
> >
> > v4:
> > - Update the wrong commit messages. (Jason)
> >
> > v3:
> > - Change nr_cpu_ids to num_online_cpus() (Maciej)
> > - Rename MAX_XDP_QUEUES to IXGBE_MAX_XDP_QS (Maciej)
> > - Rename ixgbe_determine_xdp_cpu() to ixgbe_determine_xdp_q_idx() (Maciej)
> > - Wrap ixgbe_xdp_ring_update_tail() with lock into one function (Maciej)
> >
> > v2:
> > - Adjust cpu id in ixgbe_xdp_xmit(). (Jesper)
> > - Add a fallback path. (Maciej)
> > - Adjust other parts related to xdp ring.
> > ---
> > drivers/net/ethernet/intel/ixgbe/ixgbe.h | 15 ++++-
> > drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c | 9 ++-
> > drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 64 ++++++++++++++++------
> > .../net/ethernet/intel/ixgbe/ixgbe_txrx_common.h | 1 +
> > drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 9 +--
> > 5 files changed, 73 insertions(+), 25 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
> > index a604552..1dcddea 100644
> > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
> > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
> > @@ -351,6 +351,7 @@ struct ixgbe_ring {
> > };
> > u16 rx_offset;
> > struct xdp_rxq_info xdp_rxq;
> > + spinlock_t tx_lock; /* used in XDP mode */
> > struct xsk_buff_pool *xsk_pool;
> > u16 ring_idx; /* {rx,tx,xdp}_ring back reference idx */
> > u16 rx_buf_len;
> > @@ -375,11 +376,13 @@ enum ixgbe_ring_f_enum {
> > #define IXGBE_MAX_FCOE_INDICES 8
> > #define MAX_RX_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
> > #define MAX_TX_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
> > -#define MAX_XDP_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
> > +#define IXGBE_MAX_XDP_QS (IXGBE_MAX_FDIR_INDICES + 1)
> > #define IXGBE_MAX_L2A_QUEUES 4
> > #define IXGBE_BAD_L2A_QUEUE 3
> > #define IXGBE_MAX_MACVLANS 63
> >
> > +DECLARE_STATIC_KEY_FALSE(ixgbe_xdp_locking_key);
> > +
> > struct ixgbe_ring_feature {
> > u16 limit; /* upper limit on feature indices */
> > u16 indices; /* current value of indices */
> > @@ -629,7 +632,7 @@ struct ixgbe_adapter {
> >
> > /* XDP */
> > int num_xdp_queues;
> > - struct ixgbe_ring *xdp_ring[MAX_XDP_QUEUES];
> > + struct ixgbe_ring *xdp_ring[IXGBE_MAX_XDP_QS];
> > unsigned long *af_xdp_zc_qps; /* tracks AF_XDP ZC enabled rings */
> >
> > /* TX */
> > @@ -772,6 +775,14 @@ struct ixgbe_adapter {
> > #endif /* CONFIG_IXGBE_IPSEC */
> > };
> >
> > +static inline int ixgbe_determine_xdp_q_idx(int cpu)
> > +{
> > + if (static_key_enabled(&ixgbe_xdp_locking_key))
> > + return cpu % IXGBE_MAX_XDP_QS;
> > + else
> > + return cpu;
> > +}
> > +
> > static inline u8 ixgbe_max_rss_indices(struct ixgbe_adapter *adapter)
> > {
> > switch (adapter->hw.mac.type) {
> > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
> > index 0218f6c..86b1116 100644
> > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
> > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
> > @@ -299,7 +299,10 @@ static void ixgbe_cache_ring_register(struct ixgbe_adapter *adapter)
> >
> > static int ixgbe_xdp_queues(struct ixgbe_adapter *adapter)
> > {
> > - return adapter->xdp_prog ? nr_cpu_ids : 0;
> > + int queues;
> > +
> > + queues = min_t(int, IXGBE_MAX_XDP_QS, nr_cpu_ids);
> > + return adapter->xdp_prog ? queues : 0;
> > }
> >
> > #define IXGBE_RSS_64Q_MASK 0x3F
> > @@ -947,6 +950,7 @@ static int ixgbe_alloc_q_vector(struct ixgbe_adapter *adapter,
> > ring->count = adapter->tx_ring_count;
> > ring->queue_index = xdp_idx;
> > set_ring_xdp(ring);
> > + spin_lock_init(&ring->tx_lock);
> >
> > /* assign ring to adapter */
> > WRITE_ONCE(adapter->xdp_ring[xdp_idx], ring);
> > @@ -1032,6 +1036,9 @@ static void ixgbe_free_q_vector(struct ixgbe_adapter *adapter, int v_idx)
> > adapter->q_vector[v_idx] = NULL;
> > __netif_napi_del(&q_vector->napi);
> >
> > + if (static_key_enabled(&ixgbe_xdp_locking_key))
> > + static_branch_dec(&ixgbe_xdp_locking_key);
> > +
> > /*
> > * after a call to __netif_napi_del() napi may still be used and
> > * ixgbe_get_stats64() might access the rings on this vector,
> > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> > index 14aea40..bec29f5 100644
> > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> > @@ -165,6 +165,9 @@ static int ixgbe_notify_dca(struct notifier_block *, unsigned long event,
> > MODULE_DESCRIPTION("Intel(R) 10 Gigabit PCI Express Network Driver");
> > MODULE_LICENSE("GPL v2");
> >
> > +DEFINE_STATIC_KEY_FALSE(ixgbe_xdp_locking_key);
> > +EXPORT_SYMBOL(ixgbe_xdp_locking_key);
> > +
> > static struct workqueue_struct *ixgbe_wq;
> >
> > static bool ixgbe_check_cfg_remove(struct ixgbe_hw *hw, struct pci_dev *pdev);
> > @@ -2422,13 +2425,10 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
> > xdp_do_flush_map();
> >
> > if (xdp_xmit & IXGBE_XDP_TX) {
> > - struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
> > + int index = ixgbe_determine_xdp_q_idx(smp_processor_id());
> > + struct ixgbe_ring *ring = adapter->xdp_ring[index];
> >
> > - /* Force memory writes to complete before letting h/w
> > - * know there are new descriptors to fetch.
> > - */
> > - wmb();
> > - writel(ring->next_to_use, ring->tail);
> > + ixgbe_xdp_ring_update_tail_locked(ring);
> > }
> >
> > u64_stats_update_begin(&rx_ring->syncp);
> > @@ -6320,7 +6320,7 @@ static int ixgbe_sw_init(struct ixgbe_adapter *adapter,
> > if (ixgbe_init_rss_key(adapter))
> > return -ENOMEM;
> >
> > - adapter->af_xdp_zc_qps = bitmap_zalloc(MAX_XDP_QUEUES, GFP_KERNEL);
> > + adapter->af_xdp_zc_qps = bitmap_zalloc(IXGBE_MAX_XDP_QS, GFP_KERNEL);
> > if (!adapter->af_xdp_zc_qps)
> > return -ENOMEM;
> >
> > @@ -8539,21 +8539,32 @@ static u16 ixgbe_select_queue(struct net_device *dev, struct sk_buff *skb,
> > int ixgbe_xmit_xdp_ring(struct ixgbe_adapter *adapter,
> > struct xdp_frame *xdpf)
> > {
> > - struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
> > struct ixgbe_tx_buffer *tx_buffer;
> > union ixgbe_adv_tx_desc *tx_desc;
> > + struct ixgbe_ring *ring;
> > u32 len, cmd_type;
> > dma_addr_t dma;
> > + int index, ret;
> > u16 i;
> >
> > len = xdpf->len;
> >
> > - if (unlikely(!ixgbe_desc_unused(ring)))
> > - return IXGBE_XDP_CONSUMED;
> > + index = ixgbe_determine_xdp_q_idx(smp_processor_id());
> > + ring = adapter->xdp_ring[index];
> > +
> > + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> > + spin_lock(&ring->tx_lock);
> > +
> > + if (unlikely(!ixgbe_desc_unused(ring))) {
> > + ret = IXGBE_XDP_CONSUMED;
> > + goto out;
> > + }
> >
> > dma = dma_map_single(ring->dev, xdpf->data, len, DMA_TO_DEVICE);
> > - if (dma_mapping_error(ring->dev, dma))
> > - return IXGBE_XDP_CONSUMED;
> > + if (dma_mapping_error(ring->dev, dma)) {
> > + ret = IXGBE_XDP_CONSUMED;
> > + goto out;
> > + }
> >
> > /* record the location of the first descriptor for this packet */
> > tx_buffer = &ring->tx_buffer_info[ring->next_to_use];
> > @@ -8590,7 +8601,11 @@ int ixgbe_xmit_xdp_ring(struct ixgbe_adapter *adapter,
> > tx_buffer->next_to_watch = tx_desc;
> > ring->next_to_use = i;
> >
> > - return IXGBE_XDP_TX;
> > + ret = IXGBE_XDP_TX;
> > +out:
> > + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> > + spin_unlock(&ring->tx_lock);
> > + return ret;
> > }
> >
> > netdev_tx_t ixgbe_xmit_frame_ring(struct sk_buff *skb,
> > @@ -10130,8 +10145,13 @@ static int ixgbe_xdp_setup(struct net_device *dev, struct bpf_prog *prog)
> > return -EINVAL;
> > }
> >
> > - if (nr_cpu_ids > MAX_XDP_QUEUES)
> > + /* if the number of cpus is much larger than the maximum of queues,
> > + * we should stop it and then return with NOMEM like before.
> > + */
> > + if (nr_cpu_ids > IXGBE_MAX_XDP_QS * 2)
> > return -ENOMEM;
> > + else if (nr_cpu_ids > IXGBE_MAX_XDP_QS)
> > + static_branch_inc(&ixgbe_xdp_locking_key);
> >
> > old_prog = xchg(&adapter->xdp_prog, prog);
> > need_reset = (!!prog != !!old_prog);
> > @@ -10195,12 +10215,22 @@ void ixgbe_xdp_ring_update_tail(struct ixgbe_ring *ring)
> > writel(ring->next_to_use, ring->tail);
> > }
> >
> > +void ixgbe_xdp_ring_update_tail_locked(struct ixgbe_ring *ring)
> > +{
> > + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> > + spin_lock(&ring->tx_lock);
> > + ixgbe_xdp_ring_update_tail(ring);
> > + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> > + spin_unlock(&ring->tx_lock);
> > +}
>
> It is not clear why you use a pair of spin_lock()/unlock for each ixgbe_xmit_xdp_ring()
> call, plus one other for ixgbe_xdp_ring_update_tail()
>
> I guess this could be factorized to a single spin lock/unlock in ixgbe_xdp_xmit(),
> and thus not have this ixgbe_xdp_ring_update_tail_locked() helper ?
>
I agree with what you said in ixgbe_xdp_xmit(). Two pairs of
spin_lock/unlock could be factorized to a single one, which could
decrease the times of calling lock and unlock.
Thanks,
Jason
> > +
> > static int ixgbe_xdp_xmit(struct net_device *dev, int n,
> > struct xdp_frame **frames, u32 flags)
> > {
> > struct ixgbe_adapter *adapter = netdev_priv(dev);
> > struct ixgbe_ring *ring;
> > int nxmit = 0;
> > + int index;
> > int i;
> >
> > if (unlikely(test_bit(__IXGBE_DOWN, &adapter->state)))
> > @@ -10209,10 +10239,12 @@ static int ixgbe_xdp_xmit(struct net_device *dev, int n,
> > if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
> > return -EINVAL;
> >
> > + index = ixgbe_determine_xdp_q_idx(smp_processor_id());
> > +
> > /* During program transitions its possible adapter->xdp_prog is assigned
> > * but ring has not been configured yet. In this case simply abort xmit.
> > */
> > - ring = adapter->xdp_prog ? adapter->xdp_ring[smp_processor_id()] : NULL;
> > + ring = adapter->xdp_prog ? adapter->xdp_ring[index] : NULL;
> > if (unlikely(!ring))
> > return -ENXIO;
> >
> > @@ -10230,7 +10262,7 @@ static int ixgbe_xdp_xmit(struct net_device *dev, int n,
> > }
> >
> > if (unlikely(flags & XDP_XMIT_FLUSH))
> > - ixgbe_xdp_ring_update_tail(ring);
> > + ixgbe_xdp_ring_update_tail_locked(ring);
> >
> > return nxmit;
> > }
> > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h b/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
> > index 2aeec78..f6426d9 100644
> > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
> > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
> > @@ -23,6 +23,7 @@ void ixgbe_process_skb_fields(struct ixgbe_ring *rx_ring,
> > void ixgbe_rx_skb(struct ixgbe_q_vector *q_vector,
> > struct sk_buff *skb);
> > void ixgbe_xdp_ring_update_tail(struct ixgbe_ring *ring);
> > +void ixgbe_xdp_ring_update_tail_locked(struct ixgbe_ring *ring);
> > void ixgbe_irq_rearm_queues(struct ixgbe_adapter *adapter, u64 qmask);
> >
> > void ixgbe_txrx_ring_disable(struct ixgbe_adapter *adapter, int ring);
> > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
> > index b1d22e4..82d00e4 100644
> > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
> > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
> > @@ -334,13 +334,10 @@ int ixgbe_clean_rx_irq_zc(struct ixgbe_q_vector *q_vector,
> > xdp_do_flush_map();
> >
> > if (xdp_xmit & IXGBE_XDP_TX) {
> > - struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
> > + int index = ixgbe_determine_xdp_q_idx(smp_processor_id());
> > + struct ixgbe_ring *ring = adapter->xdp_ring[index];
> >
> > - /* Force memory writes to complete before letting h/w
> > - * know there are new descriptors to fetch.
> > - */
> > - wmb();
> > - writel(ring->next_to_use, ring->tail);
> > + ixgbe_xdp_ring_update_tail_locked(ring);
> > }
> >
> > u64_stats_update_begin(&rx_ring->syncp);
> >
On Wed, Sep 1, 2021 at 3:20 PM Jason Xing <[email protected]> wrote:
>
> On Wed, Sep 1, 2021 at 1:13 PM Eric Dumazet <[email protected]> wrote:
> >
> >
> >
> > On 8/31/21 9:49 PM, [email protected] wrote:
> > > From: Jason Xing <[email protected]>
> > >
> > > Originally, ixgbe driver doesn't allow the mounting of xdpdrv if the
> > > server is equipped with more than 64 cpus online. So it turns out that
> > > the loading of xdpdrv causes the "NOMEM" failure.
> > >
> > > Actually, we can adjust the algorithm and then make it work through
> > > mapping the current cpu to some xdp ring with the protect of @tx_lock.
> > >
> > > Here're some numbers before/after applying this patch with xdp-example
> > > loaded on the eth0X:
> > >
> > > As client (tx path):
> > > Before After
> > > TCP_STREAM send-64 734.14 714.20
> > > TCP_STREAM send-128 1401.91 1395.05
> > > TCP_STREAM send-512 5311.67 5292.84
> > > TCP_STREAM send-1k 9277.40 9356.22 (not stable)
> > > TCP_RR send-1 22559.75 21844.22
> > > TCP_RR send-128 23169.54 22725.13
> > > TCP_RR send-512 21670.91 21412.56
> > >
> > > As server (rx path):
> > > Before After
> > > TCP_STREAM send-64 1416.49 1383.12
> > > TCP_STREAM send-128 3141.49 3055.50
> > > TCP_STREAM send-512 9488.73 9487.44
> > > TCP_STREAM send-1k 9491.17 9356.22 (not stable)
> > > TCP_RR send-1 23617.74 23601.60
> > > ...
> > >
> > > Notice: the TCP_RR mode is unstable as the official document explaines.
> > >
> > > I tested many times with different parameters combined through netperf.
> > > Though the result is not that accurate, I cannot see much influence on
> > > this patch. The static key is places on the hot path, but it actually
> > > shouldn't cause a huge regression theoretically.
> > >
> > > Fixes: 33fdc82f08 ("ixgbe: add support for XDP_TX action")
> > > Reported-by: kernel test robot <[email protected]>
> > > Co-developed-by: Shujin Li <[email protected]>
> > > Signed-off-by: Shujin Li <[email protected]>
> > > Signed-off-by: Jason Xing <[email protected]>
> > > ---
> > > v6:
> > > - Move the declaration of static-key to the proper position (Test Robot)
> > > - Add reported-by tag (Jason)
> > > - Add more detailed performance test results (Jason)
> > >
> > > v5:
> > > - Change back to nr_cpu_ids (Eric)
> > >
> > > v4:
> > > - Update the wrong commit messages. (Jason)
> > >
> > > v3:
> > > - Change nr_cpu_ids to num_online_cpus() (Maciej)
> > > - Rename MAX_XDP_QUEUES to IXGBE_MAX_XDP_QS (Maciej)
> > > - Rename ixgbe_determine_xdp_cpu() to ixgbe_determine_xdp_q_idx() (Maciej)
> > > - Wrap ixgbe_xdp_ring_update_tail() with lock into one function (Maciej)
> > >
> > > v2:
> > > - Adjust cpu id in ixgbe_xdp_xmit(). (Jesper)
> > > - Add a fallback path. (Maciej)
> > > - Adjust other parts related to xdp ring.
> > > ---
> > > drivers/net/ethernet/intel/ixgbe/ixgbe.h | 15 ++++-
> > > drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c | 9 ++-
> > > drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 64 ++++++++++++++++------
> > > .../net/ethernet/intel/ixgbe/ixgbe_txrx_common.h | 1 +
> > > drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 9 +--
> > > 5 files changed, 73 insertions(+), 25 deletions(-)
> > >
> > > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
> > > index a604552..1dcddea 100644
> > > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
> > > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
> > > @@ -351,6 +351,7 @@ struct ixgbe_ring {
> > > };
> > > u16 rx_offset;
> > > struct xdp_rxq_info xdp_rxq;
> > > + spinlock_t tx_lock; /* used in XDP mode */
> > > struct xsk_buff_pool *xsk_pool;
> > > u16 ring_idx; /* {rx,tx,xdp}_ring back reference idx */
> > > u16 rx_buf_len;
> > > @@ -375,11 +376,13 @@ enum ixgbe_ring_f_enum {
> > > #define IXGBE_MAX_FCOE_INDICES 8
> > > #define MAX_RX_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
> > > #define MAX_TX_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
> > > -#define MAX_XDP_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
> > > +#define IXGBE_MAX_XDP_QS (IXGBE_MAX_FDIR_INDICES + 1)
> > > #define IXGBE_MAX_L2A_QUEUES 4
> > > #define IXGBE_BAD_L2A_QUEUE 3
> > > #define IXGBE_MAX_MACVLANS 63
> > >
> > > +DECLARE_STATIC_KEY_FALSE(ixgbe_xdp_locking_key);
> > > +
> > > struct ixgbe_ring_feature {
> > > u16 limit; /* upper limit on feature indices */
> > > u16 indices; /* current value of indices */
> > > @@ -629,7 +632,7 @@ struct ixgbe_adapter {
> > >
> > > /* XDP */
> > > int num_xdp_queues;
> > > - struct ixgbe_ring *xdp_ring[MAX_XDP_QUEUES];
> > > + struct ixgbe_ring *xdp_ring[IXGBE_MAX_XDP_QS];
> > > unsigned long *af_xdp_zc_qps; /* tracks AF_XDP ZC enabled rings */
> > >
> > > /* TX */
> > > @@ -772,6 +775,14 @@ struct ixgbe_adapter {
> > > #endif /* CONFIG_IXGBE_IPSEC */
> > > };
> > >
> > > +static inline int ixgbe_determine_xdp_q_idx(int cpu)
> > > +{
> > > + if (static_key_enabled(&ixgbe_xdp_locking_key))
> > > + return cpu % IXGBE_MAX_XDP_QS;
> > > + else
> > > + return cpu;
> > > +}
> > > +
> > > static inline u8 ixgbe_max_rss_indices(struct ixgbe_adapter *adapter)
> > > {
> > > switch (adapter->hw.mac.type) {
> > > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
> > > index 0218f6c..86b1116 100644
> > > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
> > > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
> > > @@ -299,7 +299,10 @@ static void ixgbe_cache_ring_register(struct ixgbe_adapter *adapter)
> > >
> > > static int ixgbe_xdp_queues(struct ixgbe_adapter *adapter)
> > > {
> > > - return adapter->xdp_prog ? nr_cpu_ids : 0;
> > > + int queues;
> > > +
> > > + queues = min_t(int, IXGBE_MAX_XDP_QS, nr_cpu_ids);
> > > + return adapter->xdp_prog ? queues : 0;
> > > }
> > >
> > > #define IXGBE_RSS_64Q_MASK 0x3F
> > > @@ -947,6 +950,7 @@ static int ixgbe_alloc_q_vector(struct ixgbe_adapter *adapter,
> > > ring->count = adapter->tx_ring_count;
> > > ring->queue_index = xdp_idx;
> > > set_ring_xdp(ring);
> > > + spin_lock_init(&ring->tx_lock);
> > >
> > > /* assign ring to adapter */
> > > WRITE_ONCE(adapter->xdp_ring[xdp_idx], ring);
> > > @@ -1032,6 +1036,9 @@ static void ixgbe_free_q_vector(struct ixgbe_adapter *adapter, int v_idx)
> > > adapter->q_vector[v_idx] = NULL;
> > > __netif_napi_del(&q_vector->napi);
> > >
> > > + if (static_key_enabled(&ixgbe_xdp_locking_key))
> > > + static_branch_dec(&ixgbe_xdp_locking_key);
> > > +
> > > /*
> > > * after a call to __netif_napi_del() napi may still be used and
> > > * ixgbe_get_stats64() might access the rings on this vector,
> > > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> > > index 14aea40..bec29f5 100644
> > > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> > > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> > > @@ -165,6 +165,9 @@ static int ixgbe_notify_dca(struct notifier_block *, unsigned long event,
> > > MODULE_DESCRIPTION("Intel(R) 10 Gigabit PCI Express Network Driver");
> > > MODULE_LICENSE("GPL v2");
> > >
> > > +DEFINE_STATIC_KEY_FALSE(ixgbe_xdp_locking_key);
> > > +EXPORT_SYMBOL(ixgbe_xdp_locking_key);
> > > +
> > > static struct workqueue_struct *ixgbe_wq;
> > >
> > > static bool ixgbe_check_cfg_remove(struct ixgbe_hw *hw, struct pci_dev *pdev);
> > > @@ -2422,13 +2425,10 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
> > > xdp_do_flush_map();
> > >
> > > if (xdp_xmit & IXGBE_XDP_TX) {
> > > - struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
> > > + int index = ixgbe_determine_xdp_q_idx(smp_processor_id());
> > > + struct ixgbe_ring *ring = adapter->xdp_ring[index];
> > >
> > > - /* Force memory writes to complete before letting h/w
> > > - * know there are new descriptors to fetch.
> > > - */
> > > - wmb();
> > > - writel(ring->next_to_use, ring->tail);
> > > + ixgbe_xdp_ring_update_tail_locked(ring);
> > > }
> > >
> > > u64_stats_update_begin(&rx_ring->syncp);
> > > @@ -6320,7 +6320,7 @@ static int ixgbe_sw_init(struct ixgbe_adapter *adapter,
> > > if (ixgbe_init_rss_key(adapter))
> > > return -ENOMEM;
> > >
> > > - adapter->af_xdp_zc_qps = bitmap_zalloc(MAX_XDP_QUEUES, GFP_KERNEL);
> > > + adapter->af_xdp_zc_qps = bitmap_zalloc(IXGBE_MAX_XDP_QS, GFP_KERNEL);
> > > if (!adapter->af_xdp_zc_qps)
> > > return -ENOMEM;
> > >
> > > @@ -8539,21 +8539,32 @@ static u16 ixgbe_select_queue(struct net_device *dev, struct sk_buff *skb,
> > > int ixgbe_xmit_xdp_ring(struct ixgbe_adapter *adapter,
> > > struct xdp_frame *xdpf)
> > > {
> > > - struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
> > > struct ixgbe_tx_buffer *tx_buffer;
> > > union ixgbe_adv_tx_desc *tx_desc;
> > > + struct ixgbe_ring *ring;
> > > u32 len, cmd_type;
> > > dma_addr_t dma;
> > > + int index, ret;
> > > u16 i;
> > >
> > > len = xdpf->len;
> > >
> > > - if (unlikely(!ixgbe_desc_unused(ring)))
> > > - return IXGBE_XDP_CONSUMED;
> > > + index = ixgbe_determine_xdp_q_idx(smp_processor_id());
> > > + ring = adapter->xdp_ring[index];
> > > +
> > > + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> > > + spin_lock(&ring->tx_lock);
> > > +
> > > + if (unlikely(!ixgbe_desc_unused(ring))) {
> > > + ret = IXGBE_XDP_CONSUMED;
> > > + goto out;
> > > + }
> > >
> > > dma = dma_map_single(ring->dev, xdpf->data, len, DMA_TO_DEVICE);
> > > - if (dma_mapping_error(ring->dev, dma))
> > > - return IXGBE_XDP_CONSUMED;
> > > + if (dma_mapping_error(ring->dev, dma)) {
> > > + ret = IXGBE_XDP_CONSUMED;
> > > + goto out;
> > > + }
> > >
> > > /* record the location of the first descriptor for this packet */
> > > tx_buffer = &ring->tx_buffer_info[ring->next_to_use];
> > > @@ -8590,7 +8601,11 @@ int ixgbe_xmit_xdp_ring(struct ixgbe_adapter *adapter,
> > > tx_buffer->next_to_watch = tx_desc;
> > > ring->next_to_use = i;
> > >
> > > - return IXGBE_XDP_TX;
> > > + ret = IXGBE_XDP_TX;
> > > +out:
> > > + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> > > + spin_unlock(&ring->tx_lock);
> > > + return ret;
> > > }
> > >
> > > netdev_tx_t ixgbe_xmit_frame_ring(struct sk_buff *skb,
> > > @@ -10130,8 +10145,13 @@ static int ixgbe_xdp_setup(struct net_device *dev, struct bpf_prog *prog)
> > > return -EINVAL;
> > > }
> > >
> > > - if (nr_cpu_ids > MAX_XDP_QUEUES)
> > > + /* if the number of cpus is much larger than the maximum of queues,
> > > + * we should stop it and then return with NOMEM like before.
> > > + */
> > > + if (nr_cpu_ids > IXGBE_MAX_XDP_QS * 2)
> > > return -ENOMEM;
> > > + else if (nr_cpu_ids > IXGBE_MAX_XDP_QS)
> > > + static_branch_inc(&ixgbe_xdp_locking_key);
> > >
> > > old_prog = xchg(&adapter->xdp_prog, prog);
> > > need_reset = (!!prog != !!old_prog);
> > > @@ -10195,12 +10215,22 @@ void ixgbe_xdp_ring_update_tail(struct ixgbe_ring *ring)
> > > writel(ring->next_to_use, ring->tail);
> > > }
> > >
> > > +void ixgbe_xdp_ring_update_tail_locked(struct ixgbe_ring *ring)
> > > +{
> > > + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> > > + spin_lock(&ring->tx_lock);
> > > + ixgbe_xdp_ring_update_tail(ring);
> > > + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> > > + spin_unlock(&ring->tx_lock);
> > > +}
> >
> > It is not clear why you use a pair of spin_lock()/unlock for each ixgbe_xmit_xdp_ring()
> > call, plus one other for ixgbe_xdp_ring_update_tail()
> >
> > I guess this could be factorized to a single spin lock/unlock in ixgbe_xdp_xmit(),
> > and thus not have this ixgbe_xdp_ring_update_tail_locked() helper ?
> >
>
> I agree with what you said in ixgbe_xdp_xmit(). Two pairs of
> spin_lock/unlock could be factorized to a single one, which could
> decrease the times of calling lock and unlock.
>
Wait, Eric. It seems that this could decrease the times of calling.
However, this behaviour brings other changes about adding spin
lock/unlock in ixgbe_run_xdp() and ixgbe_run_xdp_zc(). Is that
necessary?
Well, now, I'm a little bit convinced that what you said is the right
way to go though I have to change some codes in ixgbe_run_xdp()/_zc().
> Thanks,
> Jason
>
> > > +
> > > static int ixgbe_xdp_xmit(struct net_device *dev, int n,
> > > struct xdp_frame **frames, u32 flags)
> > > {
> > > struct ixgbe_adapter *adapter = netdev_priv(dev);
> > > struct ixgbe_ring *ring;
> > > int nxmit = 0;
> > > + int index;
> > > int i;
> > >
> > > if (unlikely(test_bit(__IXGBE_DOWN, &adapter->state)))
> > > @@ -10209,10 +10239,12 @@ static int ixgbe_xdp_xmit(struct net_device *dev, int n,
> > > if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
> > > return -EINVAL;
> > >
> > > + index = ixgbe_determine_xdp_q_idx(smp_processor_id());
> > > +
> > > /* During program transitions its possible adapter->xdp_prog is assigned
> > > * but ring has not been configured yet. In this case simply abort xmit.
> > > */
> > > - ring = adapter->xdp_prog ? adapter->xdp_ring[smp_processor_id()] : NULL;
> > > + ring = adapter->xdp_prog ? adapter->xdp_ring[index] : NULL;
> > > if (unlikely(!ring))
> > > return -ENXIO;
> > >
> > > @@ -10230,7 +10262,7 @@ static int ixgbe_xdp_xmit(struct net_device *dev, int n,
> > > }
> > >
> > > if (unlikely(flags & XDP_XMIT_FLUSH))
> > > - ixgbe_xdp_ring_update_tail(ring);
> > > + ixgbe_xdp_ring_update_tail_locked(ring);
> > >
> > > return nxmit;
> > > }
> > > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h b/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
> > > index 2aeec78..f6426d9 100644
> > > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
> > > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
> > > @@ -23,6 +23,7 @@ void ixgbe_process_skb_fields(struct ixgbe_ring *rx_ring,
> > > void ixgbe_rx_skb(struct ixgbe_q_vector *q_vector,
> > > struct sk_buff *skb);
> > > void ixgbe_xdp_ring_update_tail(struct ixgbe_ring *ring);
> > > +void ixgbe_xdp_ring_update_tail_locked(struct ixgbe_ring *ring);
> > > void ixgbe_irq_rearm_queues(struct ixgbe_adapter *adapter, u64 qmask);
> > >
> > > void ixgbe_txrx_ring_disable(struct ixgbe_adapter *adapter, int ring);
> > > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
> > > index b1d22e4..82d00e4 100644
> > > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
> > > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
> > > @@ -334,13 +334,10 @@ int ixgbe_clean_rx_irq_zc(struct ixgbe_q_vector *q_vector,
> > > xdp_do_flush_map();
> > >
> > > if (xdp_xmit & IXGBE_XDP_TX) {
> > > - struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
> > > + int index = ixgbe_determine_xdp_q_idx(smp_processor_id());
> > > + struct ixgbe_ring *ring = adapter->xdp_ring[index];
> > >
> > > - /* Force memory writes to complete before letting h/w
> > > - * know there are new descriptors to fetch.
> > > - */
> > > - wmb();
> > > - writel(ring->next_to_use, ring->tail);
> > > + ixgbe_xdp_ring_update_tail_locked(ring);
> > > }
> > >
> > > u64_stats_update_begin(&rx_ring->syncp);
> > >