This adds small optimization for tx path: instead of allocating single
skbuff on every call to transport, allocate multiple skbuff's until
credit space allows, thus trying to send as much as possible data without
return to af_vsock.c.
Signed-off-by: Arseniy Krasnov <[email protected]>
---
Link to v1:
https://lore.kernel.org/netdev/[email protected]/
Changelog:
v1 -> v2:
- If sent something, return number of bytes sent (even in
case of error). Return error only if failed to sent first
skbuff.
net/vmw_vsock/virtio_transport_common.c | 53 ++++++++++++++++++-------
1 file changed, 39 insertions(+), 14 deletions(-)
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 6564192e7f20..3fdf1433ec28 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -196,7 +196,8 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
const struct virtio_transport *t_ops;
struct virtio_vsock_sock *vvs;
u32 pkt_len = info->pkt_len;
- struct sk_buff *skb;
+ u32 rest_len;
+ int ret;
info->type = virtio_transport_get_type(sk_vsock(vsk));
@@ -216,10 +217,6 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
vvs = vsk->trans;
- /* we can send less than pkt_len bytes */
- if (pkt_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE)
- pkt_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE;
-
/* virtio_transport_get_credit might return less than pkt_len credit */
pkt_len = virtio_transport_get_credit(vvs, pkt_len);
@@ -227,17 +224,45 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW)
return pkt_len;
- skb = virtio_transport_alloc_skb(info, pkt_len,
- src_cid, src_port,
- dst_cid, dst_port);
- if (!skb) {
- virtio_transport_put_credit(vvs, pkt_len);
- return -ENOMEM;
- }
+ ret = 0;
+ rest_len = pkt_len;
+
+ do {
+ struct sk_buff *skb;
+ size_t skb_len;
+
+ skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE, rest_len);
+
+ skb = virtio_transport_alloc_skb(info, skb_len,
+ src_cid, src_port,
+ dst_cid, dst_port);
+ if (!skb) {
+ ret = -ENOMEM;
+ break;
+ }
+
+ virtio_transport_inc_tx_pkt(vvs, skb);
+
+ ret = t_ops->send_pkt(skb);
+
+ if (ret < 0)
+ break;
- virtio_transport_inc_tx_pkt(vvs, skb);
+ rest_len -= skb_len;
+ } while (rest_len);
- return t_ops->send_pkt(skb);
+ /* Don't call this function with zero as argument:
+ * it tries to acquire spinlock and such argument
+ * makes this call useless.
+ */
+ if (rest_len)
+ virtio_transport_put_credit(vvs, rest_len);
+
+ /* Return number of bytes, if any data has been sent. */
+ if (rest_len != pkt_len)
+ ret = pkt_len - rest_len;
+
+ return ret;
}
static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs,
--
2.25.1
On Sun, Mar 19, 2023 at 09:46:10PM +0300, Arseniy Krasnov wrote:
>This adds small optimization for tx path: instead of allocating single
>skbuff on every call to transport, allocate multiple skbuff's until
>credit space allows, thus trying to send as much as possible data without
>return to af_vsock.c.
>
>Signed-off-by: Arseniy Krasnov <[email protected]>
>---
> Link to v1:
> https://lore.kernel.org/netdev/[email protected]/
>
> Changelog:
> v1 -> v2:
> - If sent something, return number of bytes sent (even in
> case of error). Return error only if failed to sent first
> skbuff.
>
> net/vmw_vsock/virtio_transport_common.c | 53 ++++++++++++++++++-------
> 1 file changed, 39 insertions(+), 14 deletions(-)
>
>diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>index 6564192e7f20..3fdf1433ec28 100644
>--- a/net/vmw_vsock/virtio_transport_common.c
>+++ b/net/vmw_vsock/virtio_transport_common.c
>@@ -196,7 +196,8 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
> const struct virtio_transport *t_ops;
> struct virtio_vsock_sock *vvs;
> u32 pkt_len = info->pkt_len;
>- struct sk_buff *skb;
>+ u32 rest_len;
>+ int ret;
>
> info->type = virtio_transport_get_type(sk_vsock(vsk));
>
>@@ -216,10 +217,6 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
>
> vvs = vsk->trans;
>
>- /* we can send less than pkt_len bytes */
>- if (pkt_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE)
>- pkt_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE;
>-
> /* virtio_transport_get_credit might return less than pkt_len credit */
> pkt_len = virtio_transport_get_credit(vvs, pkt_len);
>
>@@ -227,17 +224,45 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
> if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW)
> return pkt_len;
>
>- skb = virtio_transport_alloc_skb(info, pkt_len,
>- src_cid, src_port,
>- dst_cid, dst_port);
>- if (!skb) {
>- virtio_transport_put_credit(vvs, pkt_len);
>- return -ENOMEM;
>- }
>+ ret = 0;
>+ rest_len = pkt_len;
>+
>+ do {
>+ struct sk_buff *skb;
>+ size_t skb_len;
>+
>+ skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE, rest_len);
>+
>+ skb = virtio_transport_alloc_skb(info, skb_len,
>+ src_cid, src_port,
>+ dst_cid, dst_port);
>+ if (!skb) {
>+ ret = -ENOMEM;
>+ break;
>+ }
>+
>+ virtio_transport_inc_tx_pkt(vvs, skb);
>+
>+ ret = t_ops->send_pkt(skb);
>+
>+ if (ret < 0)
>+ break;
>
>- virtio_transport_inc_tx_pkt(vvs, skb);
>+ rest_len -= skb_len;
t_ops->send_pkt() is returning the number of bytes sent. Current
implementations always return `skb_len`, so there should be no problem,
but it would be better to put a comment here, or we should handle the
case where ret != skb_len to avoid future issues.
>+ } while (rest_len);
>
>- return t_ops->send_pkt(skb);
>+ /* Don't call this function with zero as argument:
>+ * it tries to acquire spinlock and such argument
>+ * makes this call useless.
Good point, can we do the same also for virtio_transport_get_credit()?
(Maybe in a separate patch)
I'm thinking if may be better to do it directly inside the functions,
but I don't have a strong opinion on that since we only call them here.
Thanks,
Stefano
>+ */
>+ if (rest_len)
>+ virtio_transport_put_credit(vvs, rest_len);
>+
>+ /* Return number of bytes, if any data has been sent. */
>+ if (rest_len != pkt_len)
>+ ret = pkt_len - rest_len;
>+
>+ return ret;
> }
>
> static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs,
>--
>2.25.1
>
On 20.03.2023 17:29, Stefano Garzarella wrote:
> On Sun, Mar 19, 2023 at 09:46:10PM +0300, Arseniy Krasnov wrote:
>> This adds small optimization for tx path: instead of allocating single
>> skbuff on every call to transport, allocate multiple skbuff's until
>> credit space allows, thus trying to send as much as possible data without
>> return to af_vsock.c.
>>
>> Signed-off-by: Arseniy Krasnov <[email protected]>
>> ---
>> Link to v1:
>> https://lore.kernel.org/netdev/[email protected]/
>>
>> Changelog:
>> v1 -> v2:
>> - If sent something, return number of bytes sent (even in
>> case of error). Return error only if failed to sent first
>> skbuff.
>>
>> net/vmw_vsock/virtio_transport_common.c | 53 ++++++++++++++++++-------
>> 1 file changed, 39 insertions(+), 14 deletions(-)
>>
>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>> index 6564192e7f20..3fdf1433ec28 100644
>> --- a/net/vmw_vsock/virtio_transport_common.c
>> +++ b/net/vmw_vsock/virtio_transport_common.c
>> @@ -196,7 +196,8 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
>> const struct virtio_transport *t_ops;
>> struct virtio_vsock_sock *vvs;
>> u32 pkt_len = info->pkt_len;
>> - struct sk_buff *skb;
>> + u32 rest_len;
>> + int ret;
>>
>> info->type = virtio_transport_get_type(sk_vsock(vsk));
>>
>> @@ -216,10 +217,6 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
>>
>> vvs = vsk->trans;
>>
>> - /* we can send less than pkt_len bytes */
>> - if (pkt_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE)
>> - pkt_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE;
>> -
>> /* virtio_transport_get_credit might return less than pkt_len credit */
>> pkt_len = virtio_transport_get_credit(vvs, pkt_len);
>>
>> @@ -227,17 +224,45 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
>> if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW)
>> return pkt_len;
>>
>> - skb = virtio_transport_alloc_skb(info, pkt_len,
>> - src_cid, src_port,
>> - dst_cid, dst_port);
>> - if (!skb) {
>> - virtio_transport_put_credit(vvs, pkt_len);
>> - return -ENOMEM;
>> - }
>> + ret = 0;
>> + rest_len = pkt_len;
>> +
>> + do {
>> + struct sk_buff *skb;
>> + size_t skb_len;
>> +
>> + skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE, rest_len);
>> +
>> + skb = virtio_transport_alloc_skb(info, skb_len,
>> + src_cid, src_port,
>> + dst_cid, dst_port);
>> + if (!skb) {
>> + ret = -ENOMEM;
>> + break;
>> + }
>> +
>> + virtio_transport_inc_tx_pkt(vvs, skb);
>> +
>> + ret = t_ops->send_pkt(skb);
>> +
>> + if (ret < 0)
>> + break;
>>
>> - virtio_transport_inc_tx_pkt(vvs, skb);
>> + rest_len -= skb_len;
>
> t_ops->send_pkt() is returning the number of bytes sent. Current
> implementations always return `skb_len`, so there should be no problem,
> but it would be better to put a comment here, or we should handle the
> case where ret != skb_len to avoid future issues.
Hello, thanks for review!
I see. I think i'll handle such partial sends (ret != skb_len) as error, as
it is the only thing to do - we remove 'skb_len' from user's buffer, but
'send_pkt()' returns another value, so it will be strange for me to continue
this tx loop as everything is ok. Something like this:
+
+ if (ret < 0)
+ break;
+
+ if (ret != skb_len) {
+ ret = -EFAULT;//or may be -EIO
+ break;
+ }
>
>> + } while (rest_len);
>>
>> - return t_ops->send_pkt(skb);
>> + /* Don't call this function with zero as argument:
>> + * it tries to acquire spinlock and such argument
>> + * makes this call useless.
>
> Good point, can we do the same also for virtio_transport_get_credit()?
> (Maybe in a separate patch)
>
> I'm thinking if may be better to do it directly inside the functions,
> but I don't have a strong opinion on that since we only call them here.
>
I think in this patch i can call 'virtio_transport_put_credit()' without if, but
i'll prepare separate patch which adds zero argument check to this function.
As i see, the only function suitable for such 'if' condition is 'virtio_transport_put_credit()'.
Anyway - for future use this check won't be bad.
Thanks, Arseniy
> Thanks,
> Stefano
>
>> + */
>> + if (rest_len)
>> + virtio_transport_put_credit(vvs, rest_len);
>> +
>> + /* Return number of bytes, if any data has been sent. */
>> + if (rest_len != pkt_len)
>> + ret = pkt_len - rest_len;
>> +
>> + return ret;
>> }
>>
>> static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs,
>> --
>> 2.25.1
>>
>
On Mon, Mar 20, 2023 at 09:02:19PM +0300, Arseniy Krasnov wrote:
>
>
>On 20.03.2023 17:29, Stefano Garzarella wrote:
>> On Sun, Mar 19, 2023 at 09:46:10PM +0300, Arseniy Krasnov wrote:
>>> This adds small optimization for tx path: instead of allocating single
>>> skbuff on every call to transport, allocate multiple skbuff's until
>>> credit space allows, thus trying to send as much as possible data without
>>> return to af_vsock.c.
>>>
>>> Signed-off-by: Arseniy Krasnov <[email protected]>
>>> ---
>>> Link to v1:
>>> https://lore.kernel.org/netdev/[email protected]/
>>>
>>> Changelog:
>>> v1 -> v2:
>>> - If sent something, return number of bytes sent (even in
>>> ? case of error). Return error only if failed to sent first
>>> ? skbuff.
>>>
>>> net/vmw_vsock/virtio_transport_common.c | 53 ++++++++++++++++++-------
>>> 1 file changed, 39 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>>> index 6564192e7f20..3fdf1433ec28 100644
>>> --- a/net/vmw_vsock/virtio_transport_common.c
>>> +++ b/net/vmw_vsock/virtio_transport_common.c
>>> @@ -196,7 +196,8 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
>>> ????const struct virtio_transport *t_ops;
>>> ????struct virtio_vsock_sock *vvs;
>>> ????u32 pkt_len = info->pkt_len;
>>> -??? struct sk_buff *skb;
>>> +??? u32 rest_len;
>>> +??? int ret;
>>>
>>> ????info->type = virtio_transport_get_type(sk_vsock(vsk));
>>>
>>> @@ -216,10 +217,6 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
>>>
>>> ????vvs = vsk->trans;
>>>
>>> -??? /* we can send less than pkt_len bytes */
>>> -??? if (pkt_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE)
>>> -??????? pkt_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE;
>>> -
>>> ????/* virtio_transport_get_credit might return less than pkt_len credit */
>>> ????pkt_len = virtio_transport_get_credit(vvs, pkt_len);
>>>
>>> @@ -227,17 +224,45 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
>>> ????if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW)
>>> ??????? return pkt_len;
>>>
>>> -??? skb = virtio_transport_alloc_skb(info, pkt_len,
>>> -???????????????????? src_cid, src_port,
>>> -???????????????????? dst_cid, dst_port);
>>> -??? if (!skb) {
>>> -??????? virtio_transport_put_credit(vvs, pkt_len);
>>> -??????? return -ENOMEM;
>>> -??? }
>>> +??? ret = 0;
>>> +??? rest_len = pkt_len;
>>> +
>>> +??? do {
>>> +??????? struct sk_buff *skb;
>>> +??????? size_t skb_len;
>>> +
>>> +??????? skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE, rest_len);
>>> +
>>> +??????? skb = virtio_transport_alloc_skb(info, skb_len,
>>> +???????????????????????? src_cid, src_port,
>>> +???????????????????????? dst_cid, dst_port);
>>> +??????? if (!skb) {
>>> +??????????? ret = -ENOMEM;
>>> +??????????? break;
>>> +??????? }
>>> +
>>> +??????? virtio_transport_inc_tx_pkt(vvs, skb);
>>> +
>>> +??????? ret = t_ops->send_pkt(skb);
>>> +
>>> +??????? if (ret < 0)
>>> +??????????? break;
>>>
>>> -??? virtio_transport_inc_tx_pkt(vvs, skb);
>>> +??????? rest_len -= skb_len;
>>
>> t_ops->send_pkt() is returning the number of bytes sent. Current
>> implementations always return `skb_len`, so there should be no problem,
>> but it would be better to put a comment here, or we should handle the
>> case where ret != skb_len to avoid future issues.
>
>Hello, thanks for review!
>
>I see. I think i'll handle such partial sends (ret != skb_len) as error, as
>it is the only thing to do - we remove 'skb_len' from user's buffer, but
>'send_pkt()' returns another value, so it will be strange for me to continue
>this tx loop as everything is ok. Something like this:
>+
>+ if (ret < 0)
>+ break;
>+
>+ if (ret != skb_len) {
>+ ret = -EFAULT;//or may be -EIO
>+ break;
>+ }
Good for me.
>
>>
>>> +??? } while (rest_len);
>>>
>>> -??? return t_ops->send_pkt(skb);
>>> +??? /* Don't call this function with zero as argument:
>>> +???? * it tries to acquire spinlock and such argument
>>> +???? * makes this call useless.
>>
>> Good point, can we do the same also for virtio_transport_get_credit()?
>> (Maybe in a separate patch)
>>
>> I'm thinking if may be better to do it directly inside the functions,
>> but I don't have a strong opinion on that since we only call them here.
>>
>
>I think in this patch i can call 'virtio_transport_put_credit()' without if, but
>i'll prepare separate patch which adds zero argument check to this function.
Yep, I agree.
>As i see, the only function suitable for such 'if' condition is
>'virtio_transport_put_credit()'.
Why not even for virtio_transport_get_credit() ?
When we send packets without payload (e.g. VIRTIO_VSOCK_OP_REQUEST,
VIRTIO_VSOCK_OP_SHUTDOWN) we call virtio_transport_get_credit()
with `credit` parameter equal to 0, then we acquire the spinlock but
in the end we do nothing.
>Anyway - for future use this check won't be bad.
Yep, these are minor improvements ;-)
Thanks,
Stefano