From: Eric Dumazet <eric.dumazet@gmail.com>
To: David Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Subject: Re: [PATCH] net: fix kmemcheck annotations
Date: Thu, 29 Oct 2009 11:44:48 +0100 [thread overview]
Message-ID: <4AE97220.3000004@gmail.com> (raw)
In-Reply-To: <20091029.031748.235701096.davem@davemloft.net>
David Miller a écrit :
>
> We may be trading size for performance here, I wonder if
> it's wise to move queue_mapping like that and what
> locality change we get as a result.
I agree, but could not convince me it makes a difference.
On 64bit arches, queue_mapping doesnt change its cache line location
(0xa4 -> 0xa8)
On 32bit arches, sizeof(sk_buf)=0xB0, rx and tx paths touch all
of 3 cache lines anyway.
Only thing I can think at this moment is to reorder skb so that TX
completion path dont touch all cache lines (putting together cb[]
and some not touched fields). We could probably gain one cache line miss.
It's a bit hard because of the next/prev fields that must
be first members of structure, but I believe you had some work in progress
in this area, to stick a standard list_head ?
next prev parent reply other threads:[~2009-10-29 10:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-29 10:10 [PATCH] net: fix kmemcheck annotations Eric Dumazet
2009-10-29 10:17 ` David Miller
2009-10-29 10:44 ` Eric Dumazet [this message]
2009-10-30 5:54 ` David Miller
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