As for ice bug fixed by commit b7306b42beaf ("ice: manage interrupts
during poll exit") followed by commit 23be7075b318 ("ice: fix software
generating extra interrupts") I'm seeing the similar issue also with
i40e driver.
In certain situation when busy-loop is enabled together with adaptive
coalescing, the driver occasionally misses that there are outstanding
descriptors to clean when exiting busy poll.
Try to catch the remaining work by triggering a software interrupt
when exiting busy poll. No extra interrupts will be generated when
busy polling is not used.
The issue was found when running sockperf ping-pong tcp test with
adaptive coalescing and busy poll enabled (50 as value busy_pool
and busy_read sysctl knobs) and results in huge latency spikes
with more than 100000us.
The fix is inspired from the ice driver and do the following:
1) During napi poll exit in case of busy-poll (napo_complete_done()
returns false) this is recorded to q_vector that we were in busy
loop.
2) Extends i40e_buildreg_itr() to be able to add an enforced software
interrupt into built value
2) In i40e_update_enable_itr() enforces a software interrupt trigger
if we are exiting busy poll to catch any pending clean-ups
3) Reuses unused 3rd ITR (interrupt throttle) index and set it to
20K interrupts per second to limit the number of these sw interrupts.
Test results
============
Prior:
[root@dell-per640-07 net]# sockperf ping-pong -i 10.9.9.1 --tcp -m 1000 --mps=max -t 120
sockperf: == version #3.10-no.git ==
sockperf[CLIENT] send on:sockperf: using recvfrom() to block on socket(s)
[ 0] IP = 10.9.9.1 PORT = 11111 # TCP
sockperf: Warmup stage (sending a few dummy messages)...
sockperf: Starting test...
sockperf: Test end (interrupted by timer)
sockperf: Test ended
sockperf: [Total Run] RunTime=119.999 sec; Warm up time=400 msec; SentMessages=2438563; ReceivedMessages=2438562
sockperf: ========= Printing statistics for Server No: 0
sockperf: [Valid Duration] RunTime=119.549 sec; SentMessages=2429473; ReceivedMessages=2429473
sockperf: ====> avg-latency=24.571 (std-dev=93.297, mean-ad=4.904, median-ad=1.510, siqr=1.063, cv=3.797, std-error=0.060, 99.0% ci=[24.417, 24.725])
sockperf: # dropped messages = 0; # duplicated messages = 0; # out-of-order messages = 0
sockperf: Summary: Latency is 24.571 usec
sockperf: Total 2429473 observations; each percentile contains 24294.73 observations
sockperf: ---> <MAX> observation = 103294.331
sockperf: ---> percentile 99.999 = 45.633
sockperf: ---> percentile 99.990 = 37.013
sockperf: ---> percentile 99.900 = 35.910
sockperf: ---> percentile 99.000 = 33.390
sockperf: ---> percentile 90.000 = 28.626
sockperf: ---> percentile 75.000 = 27.741
sockperf: ---> percentile 50.000 = 26.743
sockperf: ---> percentile 25.000 = 25.614
sockperf: ---> <MIN> observation = 12.220
After:
[root@dell-per640-07 net]# sockperf ping-pong -i 10.9.9.1 --tcp -m 1000 --mps=max -t 120
sockperf: == version #3.10-no.git ==
sockperf[CLIENT] send on:sockperf: using recvfrom() to block on socket(s)
[ 0] IP = 10.9.9.1 PORT = 11111 # TCP
sockperf: Warmup stage (sending a few dummy messages)...
sockperf: Starting test...
sockperf: Test end (interrupted by timer)
sockperf: Test ended
sockperf: [Total Run] RunTime=119.999 sec; Warm up time=400 msec; SentMessages=2400055; ReceivedMessages=2400054
sockperf: ========= Printing statistics for Server No: 0
sockperf: [Valid Duration] RunTime=119.549 sec; SentMessages=2391186; ReceivedMessages=2391186
sockperf: ====> avg-latency=24.965 (std-dev=5.934, mean-ad=4.642, median-ad=1.485, siqr=1.067, cv=0.238, std-error=0.004, 99.0% ci=[24.955, 24.975])
sockperf: # dropped messages = 0; # duplicated messages = 0; # out-of-order messages = 0
sockperf: Summary: Latency is 24.965 usec
sockperf: Total 2391186 observations; each percentile contains 23911.86 observations
sockperf: ---> <MAX> observation = 195.841
sockperf: ---> percentile 99.999 = 45.026
sockperf: ---> percentile 99.990 = 39.009
sockperf: ---> percentile 99.900 = 35.922
sockperf: ---> percentile 99.000 = 33.482
sockperf: ---> percentile 90.000 = 28.902
sockperf: ---> percentile 75.000 = 27.821
sockperf: ---> percentile 50.000 = 26.860
sockperf: ---> percentile 25.000 = 25.685
sockperf: ---> <MIN> observation = 12.277
Fixes: 0bcd952feec7 ("ethernet/intel: consolidate NAPI and NAPI exit")
Reported-by: Hugo Ferreira <[email protected]>
Reviewed-by: Michal Schmidt <[email protected]>
Signed-off-by: Ivan Vecera <[email protected]>
---
Changes since v3
- fixed kdoc warnings (thx Tony)
Changes since v2
- eliminated two writes in hot-path (thx Jesse)
Changes since v1
- added Fixes: tag
drivers/net/ethernet/intel/i40e/i40e.h | 1 +
drivers/net/ethernet/intel/i40e/i40e_main.c | 6 ++
.../net/ethernet/intel/i40e/i40e_register.h | 3 +
drivers/net/ethernet/intel/i40e/i40e_txrx.c | 82 ++++++++++++++-----
drivers/net/ethernet/intel/i40e/i40e_txrx.h | 1 +
5 files changed, 72 insertions(+), 21 deletions(-)
diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
index ba24f3fa92c3..2fbabcdb5bb5 100644
--- a/drivers/net/ethernet/intel/i40e/i40e.h
+++ b/drivers/net/ethernet/intel/i40e/i40e.h
@@ -955,6 +955,7 @@ struct i40e_q_vector {
struct rcu_head rcu; /* to avoid race with update stats on free */
char name[I40E_INT_NAME_STR_LEN];
bool arm_wb_state;
+ bool in_busy_poll;
int irq_num; /* IRQ assigned to this q_vector */
} ____cacheline_internodealigned_in_smp;
diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 83c020ae9625..70ead95af2c1 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -3922,6 +3922,12 @@ static void i40e_vsi_configure_msix(struct i40e_vsi *vsi)
q_vector->tx.target_itr >> 1);
q_vector->tx.current_itr = q_vector->tx.target_itr;
+ /* Set ITR for software interrupts triggered after exiting
+ * busy-loop polling.
+ */
+ wr32(hw, I40E_PFINT_ITRN(I40E_SW_ITR, vector - 1),
+ I40E_ITR_20K);
+
wr32(hw, I40E_PFINT_RATEN(vector - 1),
i40e_intrl_usec_to_reg(vsi->int_rate_limit));
diff --git a/drivers/net/ethernet/intel/i40e/i40e_register.h b/drivers/net/ethernet/intel/i40e/i40e_register.h
index 14ab642cafdb..432afbb64201 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_register.h
+++ b/drivers/net/ethernet/intel/i40e/i40e_register.h
@@ -333,8 +333,11 @@
#define I40E_PFINT_DYN_CTLN_ITR_INDX_SHIFT 3
#define I40E_PFINT_DYN_CTLN_ITR_INDX_MASK I40E_MASK(0x3, I40E_PFINT_DYN_CTLN_ITR_INDX_SHIFT)
#define I40E_PFINT_DYN_CTLN_INTERVAL_SHIFT 5
+#define I40E_PFINT_DYN_CTLN_INTERVAL_MASK I40E_MASK(0xFFF, I40E_PFINT_DYN_CTLN_INTERVAL_SHIFT)
#define I40E_PFINT_DYN_CTLN_SW_ITR_INDX_ENA_SHIFT 24
#define I40E_PFINT_DYN_CTLN_SW_ITR_INDX_ENA_MASK I40E_MASK(0x1, I40E_PFINT_DYN_CTLN_SW_ITR_INDX_ENA_SHIFT)
+#define I40E_PFINT_DYN_CTLN_SW_ITR_INDX_SHIFT 25
+#define I40E_PFINT_DYN_CTLN_SW_ITR_INDX_MASK I40E_MASK(0x3, I40E_PFINT_DYN_CTLN_SW_ITR_INDX_SHIFT)
#define I40E_PFINT_ICR0 0x00038780 /* Reset: CORER */
#define I40E_PFINT_ICR0_INTEVENT_SHIFT 0
#define I40E_PFINT_ICR0_INTEVENT_MASK I40E_MASK(0x1, I40E_PFINT_ICR0_INTEVENT_SHIFT)
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 0d7177083708..1a12b732818e 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -2630,7 +2630,22 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget,
return failure ? budget : (int)total_rx_packets;
}
-static inline u32 i40e_buildreg_itr(const int type, u16 itr)
+/**
+ * i40e_buildreg_itr - build a value for writing to I40E_PFINT_DYN_CTLN register
+ * @itr_idx: interrupt throttling index
+ * @interval: interrupt throttling interval value in usecs
+ * @force_swint: force software interrupt
+ *
+ * The function builds a value for I40E_PFINT_DYN_CTLN register that
+ * is used to update interrupt throttling interval for specified ITR index
+ * and optionally enforces a software interrupt. If the @itr_idx is equal
+ * to I40E_ITR_NONE then no interval change is applied and only @force_swint
+ * parameter is taken into account. If the interval change and enforced
+ * software interrupt are not requested then the built value just enables
+ * appropriate vector interrupt.
+ **/
+static u32 i40e_buildreg_itr(enum i40e_dyn_idx itr_idx, u16 interval,
+ bool force_swint)
{
u32 val;
@@ -2644,23 +2659,33 @@ static inline u32 i40e_buildreg_itr(const int type, u16 itr)
* an event in the PBA anyway so we need to rely on the automask
* to hold pending events for us until the interrupt is re-enabled
*
- * The itr value is reported in microseconds, and the register
- * value is recorded in 2 microsecond units. For this reason we
- * only need to shift by the interval shift - 1 instead of the
- * full value.
+ * We have to shift the given value as it is reported in microseconds
+ * and the register value is recorded in 2 microsecond units.
*/
- itr &= I40E_ITR_MASK;
+ interval >>= 1;
+ /* 1. Enable vector interrupt
+ * 2. Update the interval for the specified ITR index
+ * (I40E_ITR_NONE in the register is used to indicate that
+ * no interval update is requested)
+ */
val = I40E_PFINT_DYN_CTLN_INTENA_MASK |
- (type << I40E_PFINT_DYN_CTLN_ITR_INDX_SHIFT) |
- (itr << (I40E_PFINT_DYN_CTLN_INTERVAL_SHIFT - 1));
+ FIELD_PREP(I40E_PFINT_DYN_CTLN_ITR_INDX_MASK, itr_idx) |
+ FIELD_PREP(I40E_PFINT_DYN_CTLN_INTERVAL_MASK, interval);
+
+ /* 3. Enforce software interrupt trigger if requested
+ * (These software interrupts rate is limited by ITR2 that is
+ * set to 20K interrupts per second)
+ */
+ if (force_swint)
+ val |= I40E_PFINT_DYN_CTLN_SWINT_TRIG_MASK |
+ I40E_PFINT_DYN_CTLN_SW_ITR_INDX_ENA_MASK |
+ FIELD_PREP(I40E_PFINT_DYN_CTLN_SW_ITR_INDX_MASK,
+ I40E_SW_ITR);
return val;
}
-/* a small macro to shorten up some long lines */
-#define INTREG I40E_PFINT_DYN_CTLN
-
/* The act of updating the ITR will cause it to immediately trigger. In order
* to prevent this from throwing off adaptive update statistics we defer the
* update so that it can only happen so often. So after either Tx or Rx are
@@ -2679,8 +2704,10 @@ static inline u32 i40e_buildreg_itr(const int type, u16 itr)
static inline void i40e_update_enable_itr(struct i40e_vsi *vsi,
struct i40e_q_vector *q_vector)
{
+ enum i40e_dyn_idx itr_idx = I40E_ITR_NONE;
struct i40e_hw *hw = &vsi->back->hw;
- u32 intval;
+ u16 interval = 0;
+ u32 itr_val;
/* If we don't have MSIX, then we only need to re-enable icr0 */
if (!test_bit(I40E_FLAG_MSIX_ENA, vsi->back->flags)) {
@@ -2702,8 +2729,8 @@ static inline void i40e_update_enable_itr(struct i40e_vsi *vsi,
*/
if (q_vector->rx.target_itr < q_vector->rx.current_itr) {
/* Rx ITR needs to be reduced, this is highest priority */
- intval = i40e_buildreg_itr(I40E_RX_ITR,
- q_vector->rx.target_itr);
+ itr_idx = I40E_RX_ITR;
+ interval = q_vector->rx.target_itr;
q_vector->rx.current_itr = q_vector->rx.target_itr;
q_vector->itr_countdown = ITR_COUNTDOWN_START;
} else if ((q_vector->tx.target_itr < q_vector->tx.current_itr) ||
@@ -2712,25 +2739,36 @@ static inline void i40e_update_enable_itr(struct i40e_vsi *vsi,
/* Tx ITR needs to be reduced, this is second priority
* Tx ITR needs to be increased more than Rx, fourth priority
*/
- intval = i40e_buildreg_itr(I40E_TX_ITR,
- q_vector->tx.target_itr);
+ itr_idx = I40E_TX_ITR;
+ interval = q_vector->tx.target_itr;
q_vector->tx.current_itr = q_vector->tx.target_itr;
q_vector->itr_countdown = ITR_COUNTDOWN_START;
} else if (q_vector->rx.current_itr != q_vector->rx.target_itr) {
/* Rx ITR needs to be increased, third priority */
- intval = i40e_buildreg_itr(I40E_RX_ITR,
- q_vector->rx.target_itr);
+ itr_idx = I40E_RX_ITR;
+ interval = q_vector->rx.target_itr;
q_vector->rx.current_itr = q_vector->rx.target_itr;
q_vector->itr_countdown = ITR_COUNTDOWN_START;
} else {
/* No ITR update, lowest priority */
- intval = i40e_buildreg_itr(I40E_ITR_NONE, 0);
if (q_vector->itr_countdown)
q_vector->itr_countdown--;
}
- if (!test_bit(__I40E_VSI_DOWN, vsi->state))
- wr32(hw, INTREG(q_vector->reg_idx), intval);
+ /* Do not update interrupt control register if VSI is down */
+ if (test_bit(__I40E_VSI_DOWN, vsi->state))
+ return;
+
+ /* Update ITR interval if necessary and enforce software interrupt
+ * if we are exiting busy poll.
+ */
+ if (q_vector->in_busy_poll) {
+ itr_val = i40e_buildreg_itr(itr_idx, interval, true);
+ q_vector->in_busy_poll = false;
+ } else {
+ itr_val = i40e_buildreg_itr(itr_idx, interval, false);
+ }
+ wr32(hw, I40E_PFINT_DYN_CTLN(q_vector->reg_idx), itr_val);
}
/**
@@ -2845,6 +2883,8 @@ int i40e_napi_poll(struct napi_struct *napi, int budget)
*/
if (likely(napi_complete_done(napi, work_done)))
i40e_update_enable_itr(vsi, q_vector);
+ else
+ q_vector->in_busy_poll = true;
return min(work_done, budget - 1);
}
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.h b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
index abf15067eb5d..2cdc7de6301c 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.h
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
@@ -68,6 +68,7 @@ enum i40e_dyn_idx {
/* these are indexes into ITRN registers */
#define I40E_RX_ITR I40E_IDX_ITR0
#define I40E_TX_ITR I40E_IDX_ITR1
+#define I40E_SW_ITR I40E_IDX_ITR2
/* Supported RSS offloads */
#define I40E_DEFAULT_RSS_HENA ( \
--
2.43.0
On Sat, Mar 16, 2024 at 12:38 PM Ivan Vecera <[email protected]> wrote:
> As for ice bug fixed by commit b7306b42beaf ("ice: manage interrupts
> during poll exit") followed by commit 23be7075b318 ("ice: fix software
> generating extra interrupts") I'm seeing the similar issue also with
> i40e driver.
>
> In certain situation when busy-loop is enabled together with adaptive
> coalescing, the driver occasionally misses that there are outstanding
> descriptors to clean when exiting busy poll.
>
> Try to catch the remaining work by triggering a software interrupt
> when exiting busy poll. No extra interrupts will be generated when
> busy polling is not used.
>
> The issue was found when running sockperf ping-pong tcp test with
> adaptive coalescing and busy poll enabled (50 as value busy_pool
> and busy_read sysctl knobs) and results in huge latency spikes
> with more than 100000us.
>
> The fix is inspired from the ice driver and do the following:
> 1) During napi poll exit in case of busy-poll (napo_complete_done()
> returns false) this is recorded to q_vector that we were in busy
> loop.
> 2) Extends i40e_buildreg_itr() to be able to add an enforced software
> interrupt into built value
> 2) In i40e_update_enable_itr() enforces a software interrupt trigger
> if we are exiting busy poll to catch any pending clean-ups
> 3) Reuses unused 3rd ITR (interrupt throttle) index and set it to
> 20K interrupts per second to limit the number of these sw interrupts.
>
> Test results
> ============
> Prior:
> [root@dell-per640-07 net]# sockperf ping-pong -i 10.9.9.1 --tcp -m 1000 --mps=max -t 120
> sockperf: == version #3.10-no.git ==
> sockperf[CLIENT] send on:sockperf: using recvfrom() to block on socket(s)
>
> [ 0] IP = 10.9.9.1 PORT = 11111 # TCP
> sockperf: Warmup stage (sending a few dummy messages)...
> sockperf: Starting test...
> sockperf: Test end (interrupted by timer)
> sockperf: Test ended
> sockperf: [Total Run] RunTime=119.999 sec; Warm up time=400 msec; SentMessages=2438563; ReceivedMessages=2438562
> sockperf: ========= Printing statistics for Server No: 0
> sockperf: [Valid Duration] RunTime=119.549 sec; SentMessages=2429473; ReceivedMessages=2429473
> sockperf: ====> avg-latency=24.571 (std-dev=93.297, mean-ad=4.904, median-ad=1.510, siqr=1.063, cv=3.797, std-error=0.060, 99.0% ci=[24.417, 24.725])
> sockperf: # dropped messages = 0; # duplicated messages = 0; # out-of-order messages = 0
> sockperf: Summary: Latency is 24.571 usec
> sockperf: Total 2429473 observations; each percentile contains 24294.73 observations
> sockperf: ---> <MAX> observation = 103294.331
> sockperf: ---> percentile 99.999 = 45.633
> sockperf: ---> percentile 99.990 = 37.013
> sockperf: ---> percentile 99.900 = 35.910
> sockperf: ---> percentile 99.000 = 33.390
> sockperf: ---> percentile 90.000 = 28.626
> sockperf: ---> percentile 75.000 = 27.741
> sockperf: ---> percentile 50.000 = 26.743
> sockperf: ---> percentile 25.000 = 25.614
> sockperf: ---> <MIN> observation = 12.220
>
> After:
> [root@dell-per640-07 net]# sockperf ping-pong -i 10.9.9.1 --tcp -m 1000 --mps=max -t 120
> sockperf: == version #3.10-no.git ==
> sockperf[CLIENT] send on:sockperf: using recvfrom() to block on socket(s)
>
> [ 0] IP = 10.9.9.1 PORT = 11111 # TCP
> sockperf: Warmup stage (sending a few dummy messages)...
> sockperf: Starting test...
> sockperf: Test end (interrupted by timer)
> sockperf: Test ended
> sockperf: [Total Run] RunTime=119.999 sec; Warm up time=400 msec; SentMessages=2400055; ReceivedMessages=2400054
> sockperf: ========= Printing statistics for Server No: 0
> sockperf: [Valid Duration] RunTime=119.549 sec; SentMessages=2391186; ReceivedMessages=2391186
> sockperf: ====> avg-latency=24.965 (std-dev=5.934, mean-ad=4.642, median-ad=1.485, siqr=1.067, cv=0.238, std-error=0.004, 99.0% ci=[24.955, 24.975])
> sockperf: # dropped messages = 0; # duplicated messages = 0; # out-of-order messages = 0
> sockperf: Summary: Latency is 24.965 usec
> sockperf: Total 2391186 observations; each percentile contains 23911.86 observations
> sockperf: ---> <MAX> observation = 195.841
> sockperf: ---> percentile 99.999 = 45.026
> sockperf: ---> percentile 99.990 = 39.009
> sockperf: ---> percentile 99.900 = 35.922
> sockperf: ---> percentile 99.000 = 33.482
> sockperf: ---> percentile 90.000 = 28.902
> sockperf: ---> percentile 75.000 = 27.821
> sockperf: ---> percentile 50.000 = 26.860
> sockperf: ---> percentile 25.000 = 25.685
> sockperf: ---> <MIN> observation = 12.277
>
> Fixes: 0bcd952feec7 ("ethernet/intel: consolidate NAPI and NAPI exit")
> Reported-by: Hugo Ferreira <[email protected]>
> Reviewed-by: Michal Schmidt <[email protected]>
Yes, I am OK with v4.
Michal
> Signed-off-by: Ivan Vecera <[email protected]>
On 3/16/2024 4:38 AM, Ivan Vecera wrote:
> As for ice bug fixed by commit b7306b42beaf ("ice: manage interrupts
> during poll exit") followed by commit 23be7075b318 ("ice: fix software
> generating extra interrupts") I'm seeing the similar issue also with
> i40e driver.
>
> In certain situation when busy-loop is enabled together with adaptive
> coalescing, the driver occasionally misses that there are outstanding
> descriptors to clean when exiting busy poll.
>
> Try to catch the remaining work by triggering a software interrupt
> when exiting busy poll. No extra interrupts will be generated when
> busy polling is not used.
>
> The issue was found when running sockperf ping-pong tcp test with
> adaptive coalescing and busy poll enabled (50 as value busy_pool
> and busy_read sysctl knobs) and results in huge latency spikes
> with more than 100000us.
>
> The fix is inspired from the ice driver and do the following:
> 1) During napi poll exit in case of busy-poll (napo_complete_done()
> returns false) this is recorded to q_vector that we were in busy
> loop.
> 2) Extends i40e_buildreg_itr() to be able to add an enforced software
> interrupt into built value
> 2) In i40e_update_enable_itr() enforces a software interrupt trigger
> if we are exiting busy poll to catch any pending clean-ups
> 3) Reuses unused 3rd ITR (interrupt throttle) index and set it to
> 20K interrupts per second to limit the number of these sw interrupts.
>
> Test results
> ============
> Prior:
> [root@dell-per640-07 net]# sockperf ping-pong -i 10.9.9.1 --tcp -m 1000 --mps=max -t 120
> sockperf: == version #3.10-no.git ==
> sockperf[CLIENT] send on:sockperf: using recvfrom() to block on socket(s)
>
> [ 0] IP = 10.9.9.1 PORT = 11111 # TCP
> sockperf: Warmup stage (sending a few dummy messages)...
> sockperf: Starting test...
> sockperf: Test end (interrupted by timer)
> sockperf: Test ended
> sockperf: [Total Run] RunTime=119.999 sec; Warm up time=400 msec; SentMessages=2438563; ReceivedMessages=2438562
> sockperf: ========= Printing statistics for Server No: 0
> sockperf: [Valid Duration] RunTime=119.549 sec; SentMessages=2429473; ReceivedMessages=2429473
> sockperf: ====> avg-latency=24.571 (std-dev=93.297, mean-ad=4.904, median-ad=1.510, siqr=1.063, cv=3.797, std-error=0.060, 99.0% ci=[24.417, 24.725])
> sockperf: # dropped messages = 0; # duplicated messages = 0; # out-of-order messages = 0
> sockperf: Summary: Latency is 24.571 usec
> sockperf: Total 2429473 observations; each percentile contains 24294.73 observations
> sockperf: ---> <MAX> observation = 103294.331
> sockperf: ---> percentile 99.999 = 45.633
> sockperf: ---> percentile 99.990 = 37.013
> sockperf: ---> percentile 99.900 = 35.910
> sockperf: ---> percentile 99.000 = 33.390
> sockperf: ---> percentile 90.000 = 28.626
> sockperf: ---> percentile 75.000 = 27.741
> sockperf: ---> percentile 50.000 = 26.743
> sockperf: ---> percentile 25.000 = 25.614
> sockperf: ---> <MIN> observation = 12.220
>
> After:
> [root@dell-per640-07 net]# sockperf ping-pong -i 10.9.9.1 --tcp -m 1000 --mps=max -t 120
> sockperf: == version #3.10-no.git ==
> sockperf[CLIENT] send on:sockperf: using recvfrom() to block on socket(s)
>
> [ 0] IP = 10.9.9.1 PORT = 11111 # TCP
> sockperf: Warmup stage (sending a few dummy messages)...
> sockperf: Starting test...
> sockperf: Test end (interrupted by timer)
> sockperf: Test ended
> sockperf: [Total Run] RunTime=119.999 sec; Warm up time=400 msec; SentMessages=2400055; ReceivedMessages=2400054
> sockperf: ========= Printing statistics for Server No: 0
> sockperf: [Valid Duration] RunTime=119.549 sec; SentMessages=2391186; ReceivedMessages=2391186
> sockperf: ====> avg-latency=24.965 (std-dev=5.934, mean-ad=4.642, median-ad=1.485, siqr=1.067, cv=0.238, std-error=0.004, 99.0% ci=[24.955, 24.975])
> sockperf: # dropped messages = 0; # duplicated messages = 0; # out-of-order messages = 0
> sockperf: Summary: Latency is 24.965 usec
> sockperf: Total 2391186 observations; each percentile contains 23911.86 observations
> sockperf: ---> <MAX> observation = 195.841
> sockperf: ---> percentile 99.999 = 45.026
> sockperf: ---> percentile 99.990 = 39.009
> sockperf: ---> percentile 99.900 = 35.922
> sockperf: ---> percentile 99.000 = 33.482
> sockperf: ---> percentile 90.000 = 28.902
> sockperf: ---> percentile 75.000 = 27.821
> sockperf: ---> percentile 50.000 = 26.860
> sockperf: ---> percentile 25.000 = 25.685
> sockperf: ---> <MIN> observation = 12.277
>
> Fixes: 0bcd952feec7 ("ethernet/intel: consolidate NAPI and NAPI exit")
> Reported-by: Hugo Ferreira <[email protected]>
> Reviewed-by: Michal Schmidt <[email protected]>
> Signed-off-by: Ivan Vecera <[email protected]>
Thank you!
Reviewed-by: Jesse Brandeburg <[email protected]>
> ---
> Changes since v3
> - fixed kdoc warnings (thx Tony)
> Changes since v2
> - eliminated two writes in hot-path (thx Jesse)
> Changes since v1
> - added Fixes: tag
>
> drivers/net/ethernet/intel/i40e/i40e.h | 1 +
> drivers/net/ethernet/intel/i40e/i40e_main.c | 6 ++
> .../net/ethernet/intel/i40e/i40e_register.h | 3 +
> drivers/net/ethernet/intel/i40e/i40e_txrx.c | 82 ++++++++++++++-----
> drivers/net/ethernet/intel/i40e/i40e_txrx.h | 1 +
> 5 files changed, 72 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
> index ba24f3fa92c3..2fbabcdb5bb5 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e.h
> +++ b/drivers/net/ethernet/intel/i40e/i40e.h
> @@ -955,6 +955,7 @@ struct i40e_q_vector {
> struct rcu_head rcu; /* to avoid race with update stats on free */
> char name[I40E_INT_NAME_STR_LEN];
> bool arm_wb_state;
> + bool in_busy_poll;
> int irq_num; /* IRQ assigned to this q_vector */
> } ____cacheline_internodealigned_in_smp;
>
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
> index 83c020ae9625..70ead95af2c1 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> @@ -3922,6 +3922,12 @@ static void i40e_vsi_configure_msix(struct i40e_vsi *vsi)
> q_vector->tx.target_itr >> 1);
> q_vector->tx.current_itr = q_vector->tx.target_itr;
>
> + /* Set ITR for software interrupts triggered after exiting
> + * busy-loop polling.
> + */
> + wr32(hw, I40E_PFINT_ITRN(I40E_SW_ITR, vector - 1),
> + I40E_ITR_20K);
> +
> wr32(hw, I40E_PFINT_RATEN(vector - 1),
> i40e_intrl_usec_to_reg(vsi->int_rate_limit));
>
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_register.h b/drivers/net/ethernet/intel/i40e/i40e_register.h
> index 14ab642cafdb..432afbb64201 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_register.h
> +++ b/drivers/net/ethernet/intel/i40e/i40e_register.h
> @@ -333,8 +333,11 @@
> #define I40E_PFINT_DYN_CTLN_ITR_INDX_SHIFT 3
> #define I40E_PFINT_DYN_CTLN_ITR_INDX_MASK I40E_MASK(0x3, I40E_PFINT_DYN_CTLN_ITR_INDX_SHIFT)
> #define I40E_PFINT_DYN_CTLN_INTERVAL_SHIFT 5
> +#define I40E_PFINT_DYN_CTLN_INTERVAL_MASK I40E_MASK(0xFFF, I40E_PFINT_DYN_CTLN_INTERVAL_SHIFT)
> #define I40E_PFINT_DYN_CTLN_SW_ITR_INDX_ENA_SHIFT 24
> #define I40E_PFINT_DYN_CTLN_SW_ITR_INDX_ENA_MASK I40E_MASK(0x1, I40E_PFINT_DYN_CTLN_SW_ITR_INDX_ENA_SHIFT)
> +#define I40E_PFINT_DYN_CTLN_SW_ITR_INDX_SHIFT 25
> +#define I40E_PFINT_DYN_CTLN_SW_ITR_INDX_MASK I40E_MASK(0x3, I40E_PFINT_DYN_CTLN_SW_ITR_INDX_SHIFT)
> #define I40E_PFINT_ICR0 0x00038780 /* Reset: CORER */
> #define I40E_PFINT_ICR0_INTEVENT_SHIFT 0
> #define I40E_PFINT_ICR0_INTEVENT_MASK I40E_MASK(0x1, I40E_PFINT_ICR0_INTEVENT_SHIFT)
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> index 0d7177083708..1a12b732818e 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> @@ -2630,7 +2630,22 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget,
> return failure ? budget : (int)total_rx_packets;
> }
>
> -static inline u32 i40e_buildreg_itr(const int type, u16 itr)
> +/**
> + * i40e_buildreg_itr - build a value for writing to I40E_PFINT_DYN_CTLN register
> + * @itr_idx: interrupt throttling index
> + * @interval: interrupt throttling interval value in usecs
> + * @force_swint: force software interrupt
> + *
> + * The function builds a value for I40E_PFINT_DYN_CTLN register that
> + * is used to update interrupt throttling interval for specified ITR index
> + * and optionally enforces a software interrupt. If the @itr_idx is equal
> + * to I40E_ITR_NONE then no interval change is applied and only @force_swint
> + * parameter is taken into account. If the interval change and enforced
> + * software interrupt are not requested then the built value just enables
> + * appropriate vector interrupt.
> + **/
Thanks for adding the kdoc!
> +static u32 i40e_buildreg_itr(enum i40e_dyn_idx itr_idx, u16 interval,
> + bool force_swint)
> {
> u32 val;
>
> @@ -2644,23 +2659,33 @@ static inline u32 i40e_buildreg_itr(const int type, u16 itr)
> * an event in the PBA anyway so we need to rely on the automask
> * to hold pending events for us until the interrupt is re-enabled
> *
> - * The itr value is reported in microseconds, and the register
> - * value is recorded in 2 microsecond units. For this reason we
> - * only need to shift by the interval shift - 1 instead of the
> - * full value.
> + * We have to shift the given value as it is reported in microseconds
> + * and the register value is recorded in 2 microsecond units.
> */
> - itr &= I40E_ITR_MASK;
> + interval >>= 1;
>
> + /* 1. Enable vector interrupt
> + * 2. Update the interval for the specified ITR index
> + * (I40E_ITR_NONE in the register is used to indicate that
> + * no interval update is requested)
> + */
> val = I40E_PFINT_DYN_CTLN_INTENA_MASK |
> - (type << I40E_PFINT_DYN_CTLN_ITR_INDX_SHIFT) |
> - (itr << (I40E_PFINT_DYN_CTLN_INTERVAL_SHIFT - 1));
> + FIELD_PREP(I40E_PFINT_DYN_CTLN_ITR_INDX_MASK, itr_idx) |
> + FIELD_PREP(I40E_PFINT_DYN_CTLN_INTERVAL_MASK, interval);
> +
> + /* 3. Enforce software interrupt trigger if requested
> + * (These software interrupts rate is limited by ITR2 that is
> + * set to 20K interrupts per second)
> + */
> + if (force_swint)
> + val |= I40E_PFINT_DYN_CTLN_SWINT_TRIG_MASK |
> + I40E_PFINT_DYN_CTLN_SW_ITR_INDX_ENA_MASK |
> + FIELD_PREP(I40E_PFINT_DYN_CTLN_SW_ITR_INDX_MASK,
> + I40E_SW_ITR);
>
> return val;
> }
>
> -/* a small macro to shorten up some long lines */
> -#define INTREG I40E_PFINT_DYN_CTLN
> -
> /* The act of updating the ITR will cause it to immediately trigger. In order
> * to prevent this from throwing off adaptive update statistics we defer the
> * update so that it can only happen so often. So after either Tx or Rx are
> @@ -2679,8 +2704,10 @@ static inline u32 i40e_buildreg_itr(const int type, u16 itr)
> static inline void i40e_update_enable_itr(struct i40e_vsi *vsi,
> struct i40e_q_vector *q_vector)
> {
> + enum i40e_dyn_idx itr_idx = I40E_ITR_NONE;
> struct i40e_hw *hw = &vsi->back->hw;
> - u32 intval;
> + u16 interval = 0;
> + u32 itr_val;
>
> /* If we don't have MSIX, then we only need to re-enable icr0 */
> if (!test_bit(I40E_FLAG_MSIX_ENA, vsi->back->flags)) {
> @@ -2702,8 +2729,8 @@ static inline void i40e_update_enable_itr(struct i40e_vsi *vsi,
> */
> if (q_vector->rx.target_itr < q_vector->rx.current_itr) {
> /* Rx ITR needs to be reduced, this is highest priority */
> - intval = i40e_buildreg_itr(I40E_RX_ITR,
> - q_vector->rx.target_itr);
> + itr_idx = I40E_RX_ITR;
> + interval = q_vector->rx.target_itr;
> q_vector->rx.current_itr = q_vector->rx.target_itr;
> q_vector->itr_countdown = ITR_COUNTDOWN_START;
> } else if ((q_vector->tx.target_itr < q_vector->tx.current_itr) ||
> @@ -2712,25 +2739,36 @@ static inline void i40e_update_enable_itr(struct i40e_vsi *vsi,
> /* Tx ITR needs to be reduced, this is second priority
> * Tx ITR needs to be increased more than Rx, fourth priority
> */
> - intval = i40e_buildreg_itr(I40E_TX_ITR,
> - q_vector->tx.target_itr);
> + itr_idx = I40E_TX_ITR;
> + interval = q_vector->tx.target_itr;
> q_vector->tx.current_itr = q_vector->tx.target_itr;
> q_vector->itr_countdown = ITR_COUNTDOWN_START;
> } else if (q_vector->rx.current_itr != q_vector->rx.target_itr) {
> /* Rx ITR needs to be increased, third priority */
> - intval = i40e_buildreg_itr(I40E_RX_ITR,
> - q_vector->rx.target_itr);
> + itr_idx = I40E_RX_ITR;
> + interval = q_vector->rx.target_itr;
> q_vector->rx.current_itr = q_vector->rx.target_itr;
> q_vector->itr_countdown = ITR_COUNTDOWN_START;
> } else {
> /* No ITR update, lowest priority */
> - intval = i40e_buildreg_itr(I40E_ITR_NONE, 0);
> if (q_vector->itr_countdown)
> q_vector->itr_countdown--;
> }
>
> - if (!test_bit(__I40E_VSI_DOWN, vsi->state))
> - wr32(hw, INTREG(q_vector->reg_idx), intval);
> + /* Do not update interrupt control register if VSI is down */
> + if (test_bit(__I40E_VSI_DOWN, vsi->state))
> + return;
> +
> + /* Update ITR interval if necessary and enforce software interrupt
> + * if we are exiting busy poll.
> + */
> + if (q_vector->in_busy_poll) {
> + itr_val = i40e_buildreg_itr(itr_idx, interval, true);
> + q_vector->in_busy_poll = false;
> + } else {
> + itr_val = i40e_buildreg_itr(itr_idx, interval, false);
> + }
> + wr32(hw, I40E_PFINT_DYN_CTLN(q_vector->reg_idx), itr_val);
> }
>
> /**
> @@ -2845,6 +2883,8 @@ int i40e_napi_poll(struct napi_struct *napi, int budget)
> */
> if (likely(napi_complete_done(napi, work_done)))
> i40e_update_enable_itr(vsi, q_vector);
> + else
> + q_vector->in_busy_poll = true;
>
> return min(work_done, budget - 1);
> }
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.h b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
> index abf15067eb5d..2cdc7de6301c 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.h
> +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
> @@ -68,6 +68,7 @@ enum i40e_dyn_idx {
> /* these are indexes into ITRN registers */
> #define I40E_RX_ITR I40E_IDX_ITR0
> #define I40E_TX_ITR I40E_IDX_ITR1
> +#define I40E_SW_ITR I40E_IDX_ITR2
>
> /* Supported RSS offloads */
> #define I40E_DEFAULT_RSS_HENA ( \
> -----Original Message-----
> From: Intel-wired-lan <[email protected]> On Behalf Of Ivan Vecera
> Sent: Saturday, March 16, 2024 5:08 PM
> To: [email protected]
> Cc: Loktionov, Aleksandr <[email protected]>; moderated list:INTEL ETHERNET DRIVERS <[email protected]>; open list <[email protected]>; Chmielewski, Pawel <[email protected]>; Eric Dumazet <[email protected]>; Nguyen, Anthony L <[email protected]>; Hugo Ferreira <[email protected]>; Keller, Jacob E <[email protected]>; Jakub Kicinski <[email protected]>; Paolo Abeni <[email protected]>; David S. Miller <[email protected]>
> Subject: [Intel-wired-lan] [PATCH net v4] i40e: Enforce software interrupt during busy-poll exit
>
> As for ice bug fixed by commit b7306b42beaf ("ice: manage interrupts during poll exit") followed by commit 23be7075b318 ("ice: fix software generating extra interrupts") I'm seeing the similar issue also with i40e driver.
>
> In certain situation when busy-loop is enabled together with adaptive coalescing, the driver occasionally misses that there are outstanding descriptors to clean when exiting busy poll.
>
> Try to catch the remaining work by triggering a software interrupt when exiting busy poll. No extra interrupts will be generated when busy polling is not used.
>
> The issue was found when running sockperf ping-pong tcp test with adaptive coalescing and busy poll enabled (50 as value busy_pool and busy_read sysctl knobs) and results in huge latency spikes with more than 100000us.
>
> The fix is inspired from the ice driver and do the following:
> 1) During napi poll exit in case of busy-poll (napo_complete_done()
> returns false) this is recorded to q_vector that we were in busy
> loop.
> 2) Extends i40e_buildreg_itr() to be able to add an enforced software
> interrupt into built value
> 2) In i40e_update_enable_itr() enforces a software interrupt trigger
> if we are exiting busy poll to catch any pending clean-ups
> 3) Reuses unused 3rd ITR (interrupt throttle) index and set it to
> 20K interrupts per second to limit the number of these sw interrupts.
>
> Test results
> ============
> Prior:
> [root@dell-per640-07 net]# sockperf ping-pong -i 10.9.9.1 --tcp -m 1000 --mps=max -t 120
> sockperf: == version #3.10-no.git ==
> sockperf[CLIENT] send on:sockperf: using recvfrom() to block on socket(s)
>
> [ 0] IP = 10.9.9.1 PORT = 11111 # TCP
> sockperf: Warmup stage (sending a few dummy messages)...
> sockperf: Starting test...
> sockperf: Test end (interrupted by timer)
> sockperf: Test ended
> sockperf: [Total Run] RunTime=119.999 sec; Warm up time=400 msec; SentMessages=2438563; ReceivedMessages=2438562
> sockperf: ========= Printing statistics for Server No: 0
> sockperf: [Valid Duration] RunTime=119.549 sec; SentMessages=2429473; ReceivedMessages=2429473
> sockperf: ====> avg-latency=24.571 (std-dev=93.297, mean-ad=4.904, median-ad=1.510, siqr=1.063, cv=3.797, std-error=0.060, 99.0% ci=[24.417, 24.725])
> sockperf: # dropped messages = 0; # duplicated messages = 0; # out-of-order messages = 0
> sockperf: Summary: Latency is 24.571 usec
> sockperf: Total 2429473 observations; each percentile contains 24294.73 observations
> sockperf: ---> <MAX> observation = 103294.331
> sockperf: ---> percentile 99.999 = 45.633
> sockperf: ---> percentile 99.990 = 37.013
> sockperf: ---> percentile 99.900 = 35.910
> sockperf: ---> percentile 99.000 = 33.390
> sockperf: ---> percentile 90.000 = 28.626
> sockperf: ---> percentile 75.000 = 27.741
> sockperf: ---> percentile 50.000 = 26.743
> sockperf: ---> percentile 25.000 = 25.614
> sockperf: ---> <MIN> observation = 12.220
>
> After:
> [root@dell-per640-07 net]# sockperf ping-pong -i 10.9.9.1 --tcp -m 1000 --mps=max -t 120
> sockperf: == version #3.10-no.git ==
> sockperf[CLIENT] send on:sockperf: using recvfrom() to block on socket(s)
>
> [ 0] IP = 10.9.9.1 PORT = 11111 # TCP
> sockperf: Warmup stage (sending a few dummy messages)...
> sockperf: Starting test...
> sockperf: Test end (interrupted by timer)
> sockperf: Test ended
> sockperf: [Total Run] RunTime=119.999 sec; Warm up time=400 msec; SentMessages=2400055; ReceivedMessages=2400054
> sockperf: ========= Printing statistics for Server No: 0
> sockperf: [Valid Duration] RunTime=119.549 sec; SentMessages=2391186; ReceivedMessages=2391186
> sockperf: ====> avg-latency=24.965 (std-dev=5.934, mean-ad=4.642, median-ad=1.485, siqr=1.067, cv=0.238, std-error=0.004, 99.0% ci=[24.955, 24.975])
> sockperf: # dropped messages = 0; # duplicated messages = 0; # out-of-order messages = 0
> sockperf: Summary: Latency is 24.965 usec
> sockperf: Total 2391186 observations; each percentile contains 23911.86 observations
> sockperf: ---> <MAX> observation = 195.841
> sockperf: ---> percentile 99.999 = 45.026
> sockperf: ---> percentile 99.990 = 39.009
> sockperf: ---> percentile 99.900 = 35.922
> sockperf: ---> percentile 99.000 = 33.482
> sockperf: ---> percentile 90.000 = 28.902
> sockperf: ---> percentile 75.000 = 27.821
> sockperf: ---> percentile 50.000 = 26.860
> sockperf: ---> percentile 25.000 = 25.685
> sockperf: ---> <MIN> observation = 12.277
>
> Fixes: 0bcd952feec7 ("ethernet/intel: consolidate NAPI and NAPI exit")
> Reported-by: Hugo Ferreira <[email protected]>
> Reviewed-by: Michal Schmidt <[email protected]>
> Signed-off-by: Ivan Vecera <[email protected]>
> ---
> Changes since v3
> - fixed kdoc warnings (thx Tony)
> Changes since v2
> - eliminated two writes in hot-path (thx Jesse) Changes since v1
> - added Fixes: tag
>
> drivers/net/ethernet/intel/i40e/i40e.h | 1 +
> drivers/net/ethernet/intel/i40e/i40e_main.c | 6 ++
> .../net/ethernet/intel/i40e/i40e_register.h | 3 +
> drivers/net/ethernet/intel/i40e/i40e_txrx.c | 82 ++++++++++++++-----
> drivers/net/ethernet/intel/i40e/i40e_txrx.h | 1 +
> 5 files changed, 72 insertions(+), 21 deletions(-)
>
Tested-by: Pucha Himasekhar Reddy <[email protected]> (A Contingent worker at Intel)