Re: [PATCH net-next 1/2] net: Keep sk->sk_forward_alloc as a proper size

Shakeel Butt
2023-05-15T19:50:46Z

+Feng, Yin and Oliver

On Sun, May 14, 2023 at 11:27 PM Zhang, Cathy <cathy.zhang@intel.com> wrote:
>
>
>
> > -----Original Message-----
> > From: Shakeel Butt <shakeelb@google.com>
> > Sent: Monday, May 15, 2023 12:13 PM
> > To: Zhang, Cathy <cathy.zhang@intel.com>
> > Cc: Eric Dumazet <edumazet@google.com>; Linux MM <linux-
> > mm@kvack.org>; Cgroups <cgroups@vger.kernel.org>; Paolo Abeni
> > <pabeni@redhat.com>; davem@davemloft.net; kuba@kernel.org;
> > Brandeburg, Jesse <jesse.brandeburg@intel.com>; Srinivas, Suresh
> > <suresh.srinivas@intel.com>; Chen, Tim C <tim.c.chen@intel.com>; You,
> > Lizhen <lizhen.you@intel.com>; eric.dumazet@gmail.com;
> > netdev@vger.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@intel.com>
> > wrote:
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: Shakeel Butt <shakeelb@google.com>
> > > > Sent: Saturday, May 13, 2023 1:17 AM
> > > > To: Zhang, Cathy <cathy.zhang@intel.com>
> > > > Cc: Shakeel Butt <shakeelb@google.com>; Eric Dumazet
> > > > <edumazet@google.com>; Linux MM <linux-mm@kvack.org>; Cgroups
> > > > <cgroups@vger.kernel.org>; Paolo Abeni <pabeni@redhat.com>;
> > > > davem@davemloft.net; kuba@kernel.org; Brandeburg@google.com;
> > > > Brandeburg, Jesse <jesse.brandeburg@intel.com>; Srinivas, Suresh
> > > > <suresh.srinivas@intel.com>; Chen, Tim C <tim.c.chen@intel.com>;
> > > > You, Lizhen <lizhen.you@intel.com>; eric.dumazet@gmail.com;
> > > > netdev@vger.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?
>
> Yep, absolutely :- ) RPS (with/without patch) = +1.74

Thanks a lot Cathy.

Feng/Yin/Oliver, can you please test the patch at [1] with other
workloads used by the test robot? Basically I wanted to know if it has
any positive or negative impact on other perf benchmarks.

[1] https://lore.kernel.org/all/20230512171702.923725-1-shakeelb@google.com/

Thanks in advance.