* [PATCH] virtio_net: reduce raw_smp_processor_id() calling in virtnet_xdp_get_sq
@ 2021-08-26 8:21 Li RongQing
2021-08-30 21:10 ` Michael S. Tsirkin
0 siblings, 1 reply; 5+ messages in thread
From: Li RongQing @ 2021-08-26 8:21 UTC (permalink / raw)
To: netdev, bpf, virtualization
smp_processor_id()/raw* will be called once each when not
more queues in virtnet_xdp_get_sq() which is called in
non-preemptible context, so it's safe to call the function
smp_processor_id() once.
Signed-off-by: Li RongQing <lirongqing@baidu.com>
---
drivers/net/virtio_net.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 2e42210a6503..2a7b368c1da2 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -528,19 +528,20 @@ static int __virtnet_xdp_xmit_one(struct virtnet_info *vi,
* functions to perfectly solve these three problems at the same time.
*/
#define virtnet_xdp_get_sq(vi) ({ \
+ int cpu = smp_processor_id(); \
struct netdev_queue *txq; \
typeof(vi) v = (vi); \
unsigned int qp; \
\
if (v->curr_queue_pairs > nr_cpu_ids) { \
qp = v->curr_queue_pairs - v->xdp_queue_pairs; \
- qp += smp_processor_id(); \
+ qp += cpu; \
txq = netdev_get_tx_queue(v->dev, qp); \
__netif_tx_acquire(txq); \
} else { \
- qp = smp_processor_id() % v->curr_queue_pairs; \
+ qp = cpu % v->curr_queue_pairs; \
txq = netdev_get_tx_queue(v->dev, qp); \
- __netif_tx_lock(txq, raw_smp_processor_id()); \
+ __netif_tx_lock(txq, cpu); \
} \
v->sq + qp; \
})
--
2.33.0.69.gc420321.dirty
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] virtio_net: reduce raw_smp_processor_id() calling in virtnet_xdp_get_sq
2021-08-26 8:21 [PATCH] virtio_net: reduce raw_smp_processor_id() calling in virtnet_xdp_get_sq Li RongQing
@ 2021-08-30 21:10 ` Michael S. Tsirkin
2021-08-31 2:09 ` 答复: " Li,Rongqing
0 siblings, 1 reply; 5+ messages in thread
From: Michael S. Tsirkin @ 2021-08-30 21:10 UTC (permalink / raw)
To: Li RongQing; +Cc: netdev, bpf, virtualization
On Thu, Aug 26, 2021 at 04:21:35PM +0800, Li RongQing wrote:
> smp_processor_id()/raw* will be called once each when not
> more queues in virtnet_xdp_get_sq() which is called in
> non-preemptible context, so it's safe to call the function
> smp_processor_id() once.
>
> Signed-off-by: Li RongQing <lirongqing@baidu.com>
commit log should probably explain why it's a good idea
to replace raw_smp_processor_id with smp_processor_id
in the case of curr_queue_pairs <= nr_cpu_ids.
> ---
> drivers/net/virtio_net.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 2e42210a6503..2a7b368c1da2 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -528,19 +528,20 @@ static int __virtnet_xdp_xmit_one(struct virtnet_info *vi,
> * functions to perfectly solve these three problems at the same time.
> */
> #define virtnet_xdp_get_sq(vi) ({ \
> + int cpu = smp_processor_id(); \
> struct netdev_queue *txq; \
> typeof(vi) v = (vi); \
> unsigned int qp; \
> \
> if (v->curr_queue_pairs > nr_cpu_ids) { \
> qp = v->curr_queue_pairs - v->xdp_queue_pairs; \
> - qp += smp_processor_id(); \
> + qp += cpu; \
> txq = netdev_get_tx_queue(v->dev, qp); \
> __netif_tx_acquire(txq); \
> } else { \
> - qp = smp_processor_id() % v->curr_queue_pairs; \
> + qp = cpu % v->curr_queue_pairs; \
> txq = netdev_get_tx_queue(v->dev, qp); \
> - __netif_tx_lock(txq, raw_smp_processor_id()); \
> + __netif_tx_lock(txq, cpu); \
> } \
> v->sq + qp; \
> })
> --
> 2.33.0.69.gc420321.dirty
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* 答复: [PATCH] virtio_net: reduce raw_smp_processor_id() calling in virtnet_xdp_get_sq
2021-08-30 21:10 ` Michael S. Tsirkin
@ 2021-08-31 2:09 ` Li,Rongqing
2021-08-31 14:33 ` Michael S. Tsirkin
0 siblings, 1 reply; 5+ messages in thread
From: Li,Rongqing @ 2021-08-31 2:09 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: netdev, bpf, virtualization
> -----邮件原件-----
> 发件人: Michael S. Tsirkin <mst@redhat.com>
> 发送时间: 2021年8月31日 5:10
> 收件人: Li,Rongqing <lirongqing@baidu.com>
> 抄送: netdev@vger.kernel.org; bpf@vger.kernel.org;
> virtualization@lists.linux-foundation.org
> 主题: Re: [PATCH] virtio_net: reduce raw_smp_processor_id() calling in
> virtnet_xdp_get_sq
>
> On Thu, Aug 26, 2021 at 04:21:35PM +0800, Li RongQing wrote:
> > smp_processor_id()/raw* will be called once each when not more queues
> > in virtnet_xdp_get_sq() which is called in non-preemptible context, so
> > it's safe to call the function
> > smp_processor_id() once.
> >
> > Signed-off-by: Li RongQing <lirongqing@baidu.com>
>
> commit log should probably explain why it's a good idea to replace
> raw_smp_processor_id with smp_processor_id in the case of curr_queue_pairs
> <= nr_cpu_ids.
>
I change it as below, is it ok?
virtio_net: reduce raw_smp_processor_id() calling in virtnet_xdp_get_sq
smp_processor_id() and raw_smp_processor_id() are called once
each in virtnet_xdp_get_sq(), when curr_queue_pairs <= nr_cpu_ids,
should be merged
virtnet_xdp_get_sq() is called in non-preemptible context, so
it's safe to call the function smp_processor_id(), and keep
smp_processor_id(), and remove the calling of raw_smp_processor_id(),
avoid the wrong use virtnet_xdp_get_sq to preemptible context
in the future
-Li
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: 答复: [PATCH] virtio_net: reduce raw_smp_processor_id() calling in virtnet_xdp_get_sq
2021-08-31 2:09 ` 答复: " Li,Rongqing
@ 2021-08-31 14:33 ` Michael S. Tsirkin
2021-09-03 4:00 ` 答复: " Li,Rongqing
0 siblings, 1 reply; 5+ messages in thread
From: Michael S. Tsirkin @ 2021-08-31 14:33 UTC (permalink / raw)
To: Li,Rongqing; +Cc: netdev, bpf, virtualization
On Tue, Aug 31, 2021 at 02:09:36AM +0000, Li,Rongqing wrote:
> > -----邮件原件-----
> > 发件人: Michael S. Tsirkin <mst@redhat.com>
> > 发送时间: 2021年8月31日 5:10
> > 收件人: Li,Rongqing <lirongqing@baidu.com>
> > 抄送: netdev@vger.kernel.org; bpf@vger.kernel.org;
> > virtualization@lists.linux-foundation.org
> > 主题: Re: [PATCH] virtio_net: reduce raw_smp_processor_id() calling in
> > virtnet_xdp_get_sq
> >
> > On Thu, Aug 26, 2021 at 04:21:35PM +0800, Li RongQing wrote:
> > > smp_processor_id()/raw* will be called once each when not more queues
> > > in virtnet_xdp_get_sq() which is called in non-preemptible context, so
> > > it's safe to call the function
> > > smp_processor_id() once.
> > >
> > > Signed-off-by: Li RongQing <lirongqing@baidu.com>
> >
> > commit log should probably explain why it's a good idea to replace
> > raw_smp_processor_id with smp_processor_id in the case of curr_queue_pairs
> > <= nr_cpu_ids.
> >
>
>
> I change it as below, is it ok?
>
> virtio_net: reduce raw_smp_processor_id() calling in virtnet_xdp_get_sq
shorter:
virtio_net: s/raw_smp_processor_id/smp_processor_id/ in virtnet_xdp_get_sq
>
> smp_processor_id() and raw_smp_processor_id() are called once
> each in virtnet_xdp_get_sq(), when curr_queue_pairs <= nr_cpu_ids,
> should be merged
I'd just drop this part.
>
> virtnet_xdp_get_sq() is called in non-preemptible context, so
> it's safe to call the function smp_processor_id(), and keep
> smp_processor_id(), and remove the calling of raw_smp_processor_id(),
> avoid the wrong use virtnet_xdp_get_sq to preemptible context
> in the future
s/avoid.*/this way we'll get a warning if this is ever called in a preemptible context/
>
> -Li
^ permalink raw reply [flat|nested] 5+ messages in thread
* 答复: 答复: [PATCH] virtio_net: reduce raw_smp_processor_id() calling in virtnet_xdp_get_sq
2021-08-31 14:33 ` Michael S. Tsirkin
@ 2021-09-03 4:00 ` Li,Rongqing
0 siblings, 0 replies; 5+ messages in thread
From: Li,Rongqing @ 2021-09-03 4:00 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: netdev, bpf, virtualization
> -----邮件原件-----
> 发件人: Michael S. Tsirkin <mst@redhat.com>
> 发送时间: 2021年8月31日 22:34
> 收件人: Li,Rongqing <lirongqing@baidu.com>
> 抄送: netdev@vger.kernel.org; bpf@vger.kernel.org;
> virtualization@lists.linux-foundation.org
> 主题: Re: 答复: [PATCH] virtio_net: reduce raw_smp_processor_id() calling in
> virtnet_xdp_get_sq
>
> On Tue, Aug 31, 2021 at 02:09:36AM +0000, Li,Rongqing wrote:
> > > -----邮件原件-----
> > > 发件人: Michael S. Tsirkin <mst@redhat.com>
> > > 发送时间: 2021年8月31日 5:10
> > > 收件人: Li,Rongqing <lirongqing@baidu.com>
> > > 抄送: netdev@vger.kernel.org; bpf@vger.kernel.org;
> > > virtualization@lists.linux-foundation.org
> > > 主题: Re: [PATCH] virtio_net: reduce raw_smp_processor_id() calling in
> > > virtnet_xdp_get_sq
> > >
> > > On Thu, Aug 26, 2021 at 04:21:35PM +0800, Li RongQing wrote:
> > > > smp_processor_id()/raw* will be called once each when not more
> > > > queues in virtnet_xdp_get_sq() which is called in non-preemptible
> > > > context, so it's safe to call the function
> > > > smp_processor_id() once.
> > > >
> > > > Signed-off-by: Li RongQing <lirongqing@baidu.com>
> > >
> > > commit log should probably explain why it's a good idea to replace
> > > raw_smp_processor_id with smp_processor_id in the case of
> > > curr_queue_pairs <= nr_cpu_ids.
> > >
> >
> >
> > I change it as below, is it ok?
> >
> > virtio_net: reduce raw_smp_processor_id() calling in
> > virtnet_xdp_get_sq
>
> shorter:
>
> virtio_net: s/raw_smp_processor_id/smp_processor_id/ in virtnet_xdp_get_sq
>
>
> >
> > smp_processor_id() and raw_smp_processor_id() are called once
> > each in virtnet_xdp_get_sq(), when curr_queue_pairs <= nr_cpu_ids,
> > should be merged
>
> I'd just drop this part.
>
> >
> > virtnet_xdp_get_sq() is called in non-preemptible context, so
> > it's safe to call the function smp_processor_id(), and keep
> > smp_processor_id(), and remove the calling of raw_smp_processor_id(),
> > avoid the wrong use virtnet_xdp_get_sq to preemptible context
> > in the future
>
> s/avoid.*/this way we'll get a warning if this is ever called in a preemptible
> context/
>
Thanks, should I resend it
-Li
>
> >
> > -Li
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-09-03 4:00 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-08-26 8:21 [PATCH] virtio_net: reduce raw_smp_processor_id() calling in virtnet_xdp_get_sq Li RongQing
2021-08-30 21:10 ` Michael S. Tsirkin
2021-08-31 2:09 ` 答复: " Li,Rongqing
2021-08-31 14:33 ` Michael S. Tsirkin
2021-09-03 4:00 ` 答复: " Li,Rongqing
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).