diff mbox series

[net-next,4/4] net: call skb_defer_free_flush() before each napi_poll()

Message ID 20220516042456.3014395-5-eric.dumazet@gmail.com (mailing list archive)
State Accepted
Commit 909876500251b3b48480a840bbf9053588254eee
Delegated to: Netdev Maintainers
Headers show
Series net: polish skb defer freeing | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 7 this patch: 7
netdev/cc_maintainers warning 1 maintainers not CCed: petrm@nvidia.com
netdev/build_clang success Errors and warnings before: 9 this patch: 9
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 7 this patch: 7
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 17 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Eric Dumazet May 16, 2022, 4:24 a.m. UTC 
From: Eric Dumazet <edumazet@google.com>

skb_defer_free_flush() can consume cpu cycles,
it seems better to call it in the inner loop:

- Potentially frees page/skb that will be reallocated while hot.

- Account for the cpu cycles in the @time_limit determination.

- Keep softnet_data.defer_count small to reduce chances for
  skb_attempt_defer_free() to send an IPI.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/core/dev.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Jakub Kicinski May 16, 2022, 6:21 p.m. UTC | #1 
On Sun, 15 May 2022 21:24:56 -0700 Eric Dumazet wrote:
> -end:
> -	skb_defer_free_flush(sd);
> +end:;

Sorry for the nit pick but can I remove this and just return like we
did before f3412b3879b4? Is there a reason such "label:;}" is good?
Eric Dumazet May 16, 2022, 6:26 p.m. UTC | #2 
On Mon, May 16, 2022 at 11:21 AM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Sun, 15 May 2022 21:24:56 -0700 Eric Dumazet wrote:
> > -end:
> > -     skb_defer_free_flush(sd);
> > +end:;
>
> Sorry for the nit pick but can I remove this and just return like we
> did before f3412b3879b4? Is there a reason such "label:;}" is good?

I thought that having a return in the middle of this function would
hurt us at some point.
Jakub Kicinski May 16, 2022, 6:56 p.m. UTC | #3 
On Mon, 16 May 2022 11:26:14 -0700 Eric Dumazet wrote:
> On Mon, May 16, 2022 at 11:21 AM Jakub Kicinski <kuba@kernel.org> wrote:
> >
> > On Sun, 15 May 2022 21:24:56 -0700 Eric Dumazet wrote:  
> > > -end:
> > > -     skb_defer_free_flush(sd);
> > > +end:;  
> >
> > Sorry for the nit pick but can I remove this and just return like we
> > did before f3412b3879b4? Is there a reason such "label:;}" is good?  
> 
> I thought that having a return in the middle of this function would
> hurt us at some point.

I guess personal preference. Let's leave it unless someone else shares
my disregard for pointlessly jumping to the closing bracket :)
diff mbox series

Patch

diff --git a/net/core/dev.c b/net/core/dev.c
index ac22fedfeaf72dc0d46f4793bbd9b2d5dd301730..aabb695e25f35402bbc85602e1bb9c86d2fa209e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6654,6 +6654,8 @@  static __latent_entropy void net_rx_action(struct softirq_action *h)
 	for (;;) {
 		struct napi_struct *n;
 
+		skb_defer_free_flush(sd);
+
 		if (list_empty(&list)) {
 			if (!sd_has_rps_ipi_waiting(sd) && list_empty(&repoll))
 				goto end;
@@ -6683,8 +6685,7 @@  static __latent_entropy void net_rx_action(struct softirq_action *h)
 		__raise_softirq_irqoff(NET_RX_SOFTIRQ);
 
 	net_rps_action_and_irq_enable(sd);
-end:
-	skb_defer_free_flush(sd);
+end:;
 }
 
 struct netdev_adjacent {