From: Dmitry Vyukov <dvyukov@google.com>
Subject: Re: SLAB_TYPESAFE_BY_RCU without constructors (was Re: [PATCH v4
 13/17] khwasan: add hooks implementation)
Date: Wed, 1 Aug 2018 18:47:26 +0200
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Cc: Christopher Lameter <cl@linux.com>,
        Eric Dumazet <edumazet@google.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "Theodore Ts'o" <tytso@mit.edu>, Jan Kara <jack@suse.com>,
        linux-ext4@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
        Florian Westphal <fw@strlen.de>,
        David Miller <davem@davemloft.net>,
        NetFilter <netfilter-devel@vger.kernel.org>,
        coreteam@netfilter.org, netdev <netdev@vger.kernel.org>,
        Gerrit Renker <gerrit@erg.abdn.ac.uk>, dccp@vger.kernel.org,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        David Airl
To: Eric Dumazet <eric.dumazet@gmail.com>
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On Wed, Aug 1, 2018 at 6:25 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On 08/01/2018 09:22 AM, Christopher Lameter wrote:
>> On Wed, 1 Aug 2018, Eric Dumazet wrote:
>>
>>> The idea of having a ctor() would only be a win if all the fields that
>>> can be initialized in the ctor are contiguous and fill an integral
>>> number of cache lines.
>>
>> Ok. Its reducing code size and makes the object status more consistent.
>> Isn't that enough?
>>
>
> Prove it ;)
>
> I yet have to seen actual numbers.

Proving with numbers is required for a claimed performance improvement
at the cost of code degradation/increase. For a win-win change there
is really nothing to prove.