| Message ID | 1273225881.2261.39.camel@edumazet-laptop |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On Fri, May 7, 2010 at 5:51 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote: > Le vendredi 07 mai 2010 à 07:16 +0200, Eric Dumazet a écrit : >> Le jeudi 06 mai 2010 à 22:07 -0700, David Miller a écrit : >> >> > Looks great, applied, thanks Eric. >> >> Thanks, I have a followup to avoid one atomic in enqueue phase too ;) >> > > [PATCH net-next-2.6] rps: avoid one atomic in enqueue_to_backlog > > If CONFIG_SMP=y, then we own a queue spinlock, we can avoid the atomic > test_and_set_bit() from napi_schedule_prep(). > > We now have same number of atomic ops per netif_rx() calls than with > pre-RPS kernel. > > Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> > --- > diff --git a/net/core/dev.c b/net/core/dev.c > index 32611c8..49fa5a6 100644 > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -2426,8 +2426,10 @@ enqueue: > return NET_RX_SUCCESS; > } > > - /* Schedule NAPI for backlog device */ > - if (napi_schedule_prep(&sd->backlog)) { > + /* Schedule NAPI for backlog device > + * We can use non atomic operation since we own the queue lock > + */ > + if (!__test_and_set_bit(NAPI_STATE_SCHED, &sd->backlog.state)) { > if (!rps_ipi_queued(sd)) > ____napi_schedule(sd, &sd->backlog); > } > Why not use a wrapper function? sth. like: static inline int __napi_schedule_prep(struct napi_struct *n) { return (!__test_and_set_bit(NAPI_STATE_SCHED, &n->state) }
Le vendredi 07 mai 2010 à 18:01 +0800, Changli Gao a écrit : > On Fri, May 7, 2010 at 5:51 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote: > > Le vendredi 07 mai 2010 à 07:16 +0200, Eric Dumazet a écrit : > >> Le jeudi 06 mai 2010 à 22:07 -0700, David Miller a écrit : > >> > >> > Looks great, applied, thanks Eric. > >> > >> Thanks, I have a followup to avoid one atomic in enqueue phase too ;) > >> > > > > [PATCH net-next-2.6] rps: avoid one atomic in enqueue_to_backlog > > > > If CONFIG_SMP=y, then we own a queue spinlock, we can avoid the atomic > > test_and_set_bit() from napi_schedule_prep(). > > > > We now have same number of atomic ops per netif_rx() calls than with > > pre-RPS kernel. > > > > Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> > > --- > > diff --git a/net/core/dev.c b/net/core/dev.c > > index 32611c8..49fa5a6 100644 > > --- a/net/core/dev.c > > +++ b/net/core/dev.c > > @@ -2426,8 +2426,10 @@ enqueue: > > return NET_RX_SUCCESS; > > } > > > > - /* Schedule NAPI for backlog device */ > > - if (napi_schedule_prep(&sd->backlog)) { > > + /* Schedule NAPI for backlog device > > + * We can use non atomic operation since we own the queue lock > > + */ > > + if (!__test_and_set_bit(NAPI_STATE_SCHED, &sd->backlog.state)) { > > if (!rps_ipi_queued(sd)) > > ____napi_schedule(sd, &sd->backlog); > > } > > > > Why not use a wrapper function? > > sth. like: > > static inline int __napi_schedule_prep(struct napi_struct *n) > { > return (!__test_and_set_bit(NAPI_STATE_SCHED, &n->state) > } > For one user ? Not sure it helps code readability. Right now we all have our minds knowing every bit of this code, but next year ? -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Eric Dumazet <eric.dumazet@gmail.com> Date: Fri, 07 May 2010 11:51:21 +0200 > Le vendredi 07 mai 2010 à 07:16 +0200, Eric Dumazet a écrit : >> Le jeudi 06 mai 2010 à 22:07 -0700, David Miller a écrit : >> >> > Looks great, applied, thanks Eric. >> >> Thanks, I have a followup to avoid one atomic in enqueue phase too ;) >> > > [PATCH net-next-2.6] rps: avoid one atomic in enqueue_to_backlog > > If CONFIG_SMP=y, then we own a queue spinlock, we can avoid the atomic > test_and_set_bit() from napi_schedule_prep(). > > We now have same number of atomic ops per netif_rx() calls than with > pre-RPS kernel. > > Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Also applied, thanks Eric. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/core/dev.c b/net/core/dev.c index 32611c8..49fa5a6 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2426,8 +2426,10 @@ enqueue: return NET_RX_SUCCESS; } - /* Schedule NAPI for backlog device */ - if (napi_schedule_prep(&sd->backlog)) { + /* Schedule NAPI for backlog device + * We can use non atomic operation since we own the queue lock + */ + if (!__test_and_set_bit(NAPI_STATE_SCHED, &sd->backlog.state)) { if (!rps_ipi_queued(sd)) ____napi_schedule(sd, &sd->backlog); }