linux-kernel - Re: [PATCH v4 01/21] net/tcp: Prepare tcp_md5sig

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Message-ID: <c4224fa7-c206-17d3-641b-6f3f53dd813d@arista.com>
Date:   Tue, 21 Feb 2023 14:52:49 +0000
From:   Dmitry Safonov <dima@...sta.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>
Cc:     linux-kernel@...r.kernel.org, David Ahern <dsahern@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Andy Lutomirski <luto@...capital.net>,
        Ard Biesheuvel <ardb@...nel.org>,
        Bob Gilligan <gilligan@...sta.com>,
        David Laight <David.Laight@...lab.com>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Eric Biggers <ebiggers@...nel.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Francesco Ruggeri <fruggeri05@...il.com>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Ivan Delalande <colona@...sta.com>,
        Leonard Crestez <cdleonard@...il.com>,
        Salam Noureddine <noureddine@...sta.com>,
        netdev@...r.kernel.org
Subject: Re: [PATCH v4 01/21] net/tcp: Prepare tcp_md5sig_pool for TCP-AO

On 2/21/23 02:43, Herbert Xu wrote:
> On Mon, Feb 20, 2023 at 04:57:20PM +0000, Dmitry Safonov wrote:
> . 
>> Do you have a timeline for that work?
>> And if you don't mind I keep re-iterating, as I'm trying to address TCP
>> reviews and missed functionality/selftests.
> 
> I'm hoping to get it ready for the next merge window.

Nice! I'll mark this 1/21 patch as [draft], mentioning your work as it
will need to be re-made using per-request keys.
Still, I will keep iterating TCP-AO patches set during 6.3 RCs in order
to get more reviews/suggestions related to TCP changes.

>> 1) before your per-request key patches - it's not possible.
>> 2) after your patches - my question would be: "is it better to
>> kmalloc(GFP_ATOMIC) in RX/TX for every signed TCP segment, rather than
>> pre-allocate it?"
>>
>> The price of (2) may just well be negligible, but worth measuring before
>> switching.
> 
> Please keep in mind that you're already performing crypto which
> is usually a lot slower than a kmalloc.  In any case, if there is
> any optimisation to be done to make the kmalloc faster by using
> pools, then that optimisation should go into mm.

Fair point. Probably, kmalloc() is negligible. I'll measure as I have a
patch for iperf for TCP-MD5/TCP-AO measurements.

Thanks,
          Dmitry