From: Benjamin LaHaise <bcrl@kvack.org>
Date: Tue, 3 Jan 2006 22:06:50 +0000 (-0800)
Subject: [NET]: Speed up __alloc_skb()
X-Git-Tag: v2.6.16-rc1~474^2~22^2~9^2~24
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4947d3ef8de7b4f42aed6ea9ba689dc8fb45b5a5;p=pandora-kernel.git

[NET]: Speed up __alloc_skb()

From: Benjamin LaHaise <bcrl@kvack.org>

In __alloc_skb(), the use of skb_shinfo() which casts a u8 * to the
shared info structure results in gcc being forced to do a reload of the
pointer since it has no information on possible aliasing.  Fix this by
using a pointer to refer to skb_shared_info.

By initializing skb_shared_info sequentially, the write combining buffers
can reduce the number of memory transactions to a single write.  Reorder
the initialization in __alloc_skb() to match the structure definition.
There is also an alignment issue on 64 bit systems with skb_shared_info
by converting nr_frags to a short everything packs up nicely.

Also, pass the slab cache pointer according to the fclone flag instead
of using two almost identical function calls.

This raises bw_unix performance up to a peak of 707KB/s when combined
with the spinlock patch.  It should help other networking protocols, too.

Signed-off-by: David S. Miller <davem@davemloft.net>
---

Reading git-diff-tree failed