From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: gallatin@myri.com, mason@myri.com, netdev@vger.kernel.org
Subject: Re: [PATCH net-next] myri10ge: fix truesize underestimation
Date: Thu, 20 Oct 2011 17:03:26 -0400 (EDT) [thread overview]
Message-ID: <20111020.170326.2193877307745965380.davem@davemloft.net> (raw)
In-Reply-To: <1319144356.2854.36.camel@edumazet-laptop>
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 20 Oct 2011 22:59:16 +0200
> Le jeudi 20 octobre 2011 à 16:45 -0400, Andrew Gallatin a écrit :
>> On 10/20/11 16:44, Eric Dumazet wrote:
>> > Le jeudi 20 octobre 2011 à 15:33 -0500, Jon Mason a écrit :
>> >> On Thu, Oct 20, 2011 at 3:10 PM, Eric Dumazet<eric.dumazet@gmail.com> wrote:
>> >>> skb->truesize must account for allocated memory, not the used part of
>> >>> it. Doing this work is important to avoid unexpected OOM situations.
>> >>>
>> >>> Signed-off-by: Eric Dumazet<eric.dumazet@gmail.com>
>> >>
>> >> Acked-by: Jon Mason<mason@myri.com>
>> >
>> > Thanks for reviewing Jon !
>> >
>> >
>>
>> Please wait a second.. I think the patch is incorrect.
>>
>> There is already code in myri10ge_rx_skb_build() which
>> attempts to set the truesize. However, it sets it to
>> the used, rather than the allocated size so it is apparently
>> incorrect.
>>
>> I'd prefer we fix that code.
>
> Well, I believe I did exactly that :)
>
> truesize of initial skb is fine.
>
> Then for everay frag added, you must add to skb-truesize the allocated
> memory for this frag.
>
> You add frags of a given size (small or big)
>
> In the end, its truesize += bytes * number_of_frags
>
> (bytes being small_size or big_size)
Right, I believe Eric's patch is correct, and I intend to apply it.
next prev parent reply other threads:[~2011-10-20 21:03 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-20 20:10 [PATCH net-next] myri10ge: fix truesize underestimation Eric Dumazet
2011-10-20 20:33 ` Jon Mason
2011-10-20 20:44 ` Eric Dumazet
2011-10-20 20:45 ` Andrew Gallatin
2011-10-20 20:59 ` Eric Dumazet
2011-10-20 21:03 ` David Miller [this message]
2011-10-20 21:04 ` Andrew Gallatin
2011-10-20 21:06 ` Eric Dumazet
2011-10-20 21:42 ` David Miller
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