netdev - Re: [PATCH net-next 1/2] net: Keep sk->sk_forward

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Date: Sun, 14 May 2023 21:13:20 -0700
From: Shakeel Butt <shakeelb@...gle.com>
To: "Zhang, Cathy" <cathy.zhang@...el.com>
Cc: Eric Dumazet <edumazet@...gle.com>, Linux MM <linux-mm@...ck.org>, 
	Cgroups <cgroups@...r.kernel.org>, Paolo Abeni <pabeni@...hat.com>, 
	"davem@...emloft.net" <davem@...emloft.net>, "kuba@...nel.org" <kuba@...nel.org>, 
	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>, "Srinivas, Suresh" <suresh.srinivas@...el.com>, 
	"Chen, Tim C" <tim.c.chen@...el.com>, "You, Lizhen" <lizhen.you@...el.com>, 
	"eric.dumazet@...il.com" <eric.dumazet@...il.com>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 1/2] net: Keep sk->sk_forward_alloc as a proper size

On Sun, May 14, 2023 at 8:46 PM Zhang, Cathy <cathy.zhang@...el.com> wrote:
>
>
>
> > -----Original Message-----
> > From: Shakeel Butt <shakeelb@...gle.com>
> > Sent: Saturday, May 13, 2023 1:17 AM
> > To: Zhang, Cathy <cathy.zhang@...el.com>
> > Cc: Shakeel Butt <shakeelb@...gle.com>; Eric Dumazet
> > <edumazet@...gle.com>; Linux MM <linux-mm@...ck.org>; Cgroups
> > <cgroups@...r.kernel.org>; Paolo Abeni <pabeni@...hat.com>;
> > davem@...emloft.net; kuba@...nel.org; Brandeburg@...gle.com;
> > Brandeburg, Jesse <jesse.brandeburg@...el.com>; Srinivas, Suresh
> > <suresh.srinivas@...el.com>; Chen, Tim C <tim.c.chen@...el.com>; You,
> > Lizhen <lizhen.you@...el.com>; eric.dumazet@...il.com;
> > netdev@...r.kernel.org
> > Subject: Re: [PATCH net-next 1/2] net: Keep sk->sk_forward_alloc as a proper
> > size
> >
> > On Fri, May 12, 2023 at 05:51:40AM +0000, Zhang, Cathy wrote:
> > >
> > >
> > [...]
> > > >
> > > > Thanks a lot. This tells us that one or both of following scenarios
> > > > are
> > > > happening:
> > > >
> > > > 1. In the softirq recv path, the kernel is processing packets from
> > > > multiple memcgs.
> > > >
> > > > 2. The process running on the CPU belongs to memcg which is
> > > > different from the memcgs whose packets are being received on that CPU.
> > >
> > > Thanks for sharing the points, Shakeel! Is there any trace records you
> > > want to collect?
> > >
> >
> > Can you please try the following patch and see if there is any improvement?
>
> Hi Shakeel,
>
> Try the following patch, the data of 'perf top' from system wide indicates that
> the overhead of page_counter_cancel is dropped from 15.52% to 4.82%.
>
> Without patch:
>     15.52%  [kernel]            [k] page_counter_cancel
>     12.30%  [kernel]            [k] page_counter_try_charge
>     11.97%  [kernel]            [k] try_charge_memcg
>
> With patch:
>     10.63%  [kernel]            [k] page_counter_try_charge
>      9.49%  [kernel]            [k] try_charge_memcg
>      4.82%  [kernel]            [k] page_counter_cancel
>
> The patch is applied on the latest net-next/main:
> befcc1fce564 ("sfc: fix use-after-free in efx_tc_flower_record_encap_match()")
>

Thanks a lot Cathy for testing. Do you see any performance improvement
for the memcached benchmark with the patch?