netdev - Re: [RFC PATCH v2 0/6] Reduce cache miss for snmp_fold

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Message-ID: <20160906124413.GC27658@localhost.localdomain>
Date:   Tue, 6 Sep 2016 09:44:13 -0300
From:   Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To:     Jia He <hejianet@...il.com>
Cc:     netdev@...r.kernel.org, linux-sctp@...r.kernel.org,
        linux-kernel@...r.kernel.org, davem@...emloft.net,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        James Morris <jmorris@...ei.org>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Patrick McHardy <kaber@...sh.net>,
        Vlad Yasevich <vyasevich@...il.com>,
        Neil Horman <nhorman@...driver.com>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        Herbert Xu <herbert@...dor.apana.org.au>
Subject: Re: [RFC PATCH v2 0/6] Reduce cache miss for snmp_fold_field

On Tue, Sep 06, 2016 at 10:30:03AM +0800, Jia He wrote:
...
> v2:
> - 1/6 fix bug in udplite statistics. 
> - 1/6 snmp_seq_show is split into 2 parts
> 
> Jia He (6):
>   proc: Reduce cache miss in {snmp,netstat}_seq_show
>   proc: Reduce cache miss in snmp6_seq_show
>   proc: Reduce cache miss in sctp_snmp_seq_show
>   proc: Reduce cache miss in xfrm_statistics_seq_show
>   ipv6: Remove useless parameter in __snmp6_fill_statsdev
>   net: Suppress the "Comparison to NULL could be written" warning

Hi Jia,

Did you try to come up with a generic interface for this, like
snmp_fold_fields64() (note the fieldS) or snmp_fold_field64_batch() ?

Sounds like we have the same code in several places and seems they all
operate very similarly. They have a percpu table, an identified max, a
destination buffer.. 

If this is possible, this would reduce the possibility of hiccups in a
particular code.

  Marcelo