From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: alexander.h.duyck@intel.com, netdev@vger.kernel.org,
jeffrey.t.kirsher@intel.com
Subject: Re: [PATCH 1/3] skb: Drop bad code from pskb_expand_head
Date: Sun, 06 May 2012 13:13:37 -0400 (EDT) [thread overview]
Message-ID: <20120506.131337.363109018749374511.davem@davemloft.net> (raw)
In-Reply-To: <1336196130.3752.483.camel@edumazet-glaptop>
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Sat, 05 May 2012 07:35:30 +0200
> On Fri, 2012-05-04 at 17:26 -0700, Alexander Duyck wrote:
>> The fast-path for pskb_expand_head contains a check where the size plus the
>> unaligned size of skb_shared_info is compared against the size of the data
>> buffer. This code path has two issues. First is the fact that after the
>> recent changes by Eric Dumazet to __alloc_skb and build_skb the shared info
>> is always placed in the optimal spot for a buffer size making this check
>> unnecessary. The second issue is the fact that the check doesn't take into
>> account the aligned size of shared info. As a result the code burns cycles
>> doing a memcpy with nothing actually being shifted.
>>
>> Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
...
> Acked-by: Eric Dumazet <edumazet@google.com>
Applied.
next prev parent reply other threads:[~2012-05-06 17:13 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-05 0:26 [PATCH 0/3] First pass of cleanups for pskb_expand_head Alexander Duyck
2012-05-05 0:26 ` [PATCH 1/3] skb: Drop bad code from pskb_expand_head Alexander Duyck
2012-05-05 5:35 ` Eric Dumazet
2012-05-06 17:13 ` David Miller [this message]
2012-05-05 0:26 ` [PATCH 2/3] skb: Drop "fastpath" variable for skb_cloned check in pskb_expand_head Alexander Duyck
2012-05-05 5:37 ` Eric Dumazet
2012-05-06 17:13 ` David Miller
2012-05-05 0:26 ` [PATCH 3/3] skb: Add inline helper for getting the skb end offset from head Alexander Duyck
2012-05-05 5:39 ` Eric Dumazet
2012-05-06 17:13 ` David Miller
2012-05-05 5:44 ` [PATCH 0/3] First pass of cleanups for pskb_expand_head Eric Dumazet
2012-05-05 6:51 ` Alexander Duyck
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