netdev - Re: [PATCH net-next] tcp: Make GRO completion function inline

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Date: Mon, 3 Jul 2023 10:00:33 -0700
From: Michael Chan <michael.chan@...adcom.com>
To: Alexander Lobakin <aleksander.lobakin@...el.com>
Cc: Parav Pandit <parav@...dia.com>, aelior@...vell.com, skalluru@...vell.com, 
	manishc@...vell.com, netdev@...r.kernel.org, edumazet@...gle.com, 
	davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com, dsahern@...nel.org
Subject: Re: [PATCH net-next] tcp: Make GRO completion function inline

On Mon, Jul 3, 2023 at 9:52 AM Alexander Lobakin
<aleksander.lobakin@...el.com> wrote:
>
> From: Michael Chan <michael.chan@...adcom.com>
> Date: Sat, 1 Jul 2023 16:09:53 -0700
>
> > On Sun, Jun 11, 2023 at 7:08 AM Parav Pandit <parav@...dia.com> wrote:
> >>
> >> At 100G link speed, with 1500 MTU, at 8.2 mpps, if device does GRO for
> >> 64K message size, currently it results in ~190k calls to
> >> tcp_gro_complete() in data path.
> >>
> >> Inline this small routine to avoid above number of function calls.
> >>
> >> Suggested-by: David Ahern <dsahern@...nel.org>
> >> Signed-off-by: Parav Pandit <parav@...dia.com>
> >>
> >> ---
> >> This patch is untested as I do not have the any of the 3 hw devices
> >> calling this routine.
> >>
> >> qede, bnxt and bnx2x maintainers,
> >>
> >> Can you please verify it with your devices if it reduces cpu
> >> utilization marginally or it stays same or has some side effects?
> >>
> >> ---
> >
> > Sorry for the delay.  It works fine on bnxt NICs running hardware GRO.
> > No noticeable changes in throughput or CPU utilization running simple
> > netperf.  Thanks.
> >
> > Tested-by: Michael Chan <michael.chan@...adcom.com>
> > Reviewed-by: Michael Chan <michael.chan@...adcom.com>
> Why is this needed then if it gives nothing? :D
>

I only tested at 50G link speed and about 64K aggregation size.  At
higher speed and smaller aggregation size, perhaps it will show
slightly better performance or CPU utilization.

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