netdev - Re: tc tp creation performance degratation since kernel 5.1

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Message-ID: <e11118334595e6517e618e80406e0135402cacf1.camel@redhat.com>
Date:   Wed, 12 Jun 2019 14:30:37 +0200
From:   Paolo Abeni <pabeni@...hat.com>
To:     Jiri Pirko <jiri@...nulli.us>, netdev@...r.kernel.org
Cc:     vladbu@...lanox.com, pablo@...filter.org, xiyou.wangcong@...il.com,
        jhs@...atatu.com, mlxsw@...lanox.com, alexanderk@...lanox.com
Subject: Re: tc tp creation performance degratation since kernel 5.1

Hi,

On Wed, 2019-06-12 at 14:03 +0200, Jiri Pirko wrote:
> I did simple prifiling using perf. Output on 5.1 kernel:
>     77.85%  tc               [kernel.kallsyms]  [k] tcf_chain_tp_find
>      3.30%  tc               [kernel.kallsyms]  [k] _raw_spin_unlock_irqrestore
>      1.33%  tc_pref_scale.s  [kernel.kallsyms]  [k] do_syscall_64
>      0.60%  tc_pref_scale.s  libc-2.28.so       [.] malloc
>      0.55%  tc               [kernel.kallsyms]  [k] mutex_spin_on_owner
>      0.51%  tc               libc-2.28.so       [.] __memset_sse2_unaligned_erms
>      0.40%  tc_pref_scale.s  libc-2.28.so       [.] __gconv_transform_utf8_internal
>      0.38%  tc_pref_scale.s  libc-2.28.so       [.] _int_free
>      0.37%  tc_pref_scale.s  libc-2.28.so       [.] __GI___strlen_sse2
>      0.37%  tc               [kernel.kallsyms]  [k] idr_get_free
> 
> Output on net-next:
>     39.26%  tc               [kernel.vmlinux]  [k] lock_is_held_type

It looks like you have lockdep enabled here, but not on the 5.1 build.

That would explain such a large perf difference.

Can you please double check?

thanks,

Paolo