netdev - Re: [PATCH v2] net/core: Increase default optmem

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Date:   Tue, 16 Jan 2018 19:11:37 +0100
From:   Stephan Mueller <smueller@...onox.de>
To:     Björn 'besser82' Esser 
        <besser82@...oraproject.org>
Cc:     David Miller <davem@...emloft.net>, waltje@...lt.nl.mugnet.org,
        flla@...d.uni-sb.de, A.Cox@...nsea.ac.uk,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        trivial@...nel.org, labbott@...hat.com, zbyszek@...waw.pl,
        linux-crypto@...r.kernel.org
Subject: Re: [PATCH v2] net/core: Increase default optmem_max limit

Am Dienstag, 16. Januar 2018, 18:16:43 CET schrieb Björn 'besser82' Esser:

Hi Björn,

> With the new Linux Kernel Crypto API User Space Interface
> and its underlying AF_ALG socket, the current default value
> for `net.core.optmem_max` can be exhausted pretty quick when
> using asynchronous IO; on 32 bit systems it is not even enough
> for sending about 10 IOVECs at once to the socket interface.
> 
> To provide consumers of this new user space interface a well
> sufficient and reasonable maximum ancillary buffer size per
> socket by default, the limit is increased to four times of
> the previous setting:
> 
>   * 32 bit systems:  from 10240 bytes to 40960 bytes
>   * 64 bit systems:  from 20480 bytes to 81920 bytes
> 
> This allows for sending 32/64 (32/64 bit) parallel IOVECs at
> once to the socket interface, which should be enough for use
> in real world applications.
> 
> Signed-off-by: Björn Esser <besser82@...oraproject.org>

Considering NR_FILE defining the default maximum number of file descriptors, 
at max 335 MB of RAM (32 bit) or 670 MB (64 bit) could be allocated which I 
would assume to be ok in current systems.

Reviewed-by: Stephan Mueller <smueller@...onox.de>

Ciao
Stephan