From: Eric Dumazet <edumazet@google.com>
Date: Wed, 26 Sep 2012 06:46:57 +0000 (+0000)
Subject: net: use bigger pages in __netdev_alloc_frag
X-Git-Tag: omap-for-v3.7-rc1/fixes-cpufreq-signed~47^2~57
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=69b08f62e17439ee3d436faf0b9a7ca6fffb78db;p=pandora-kernel.git

net: use bigger pages in __netdev_alloc_frag

We currently use percpu order-0 pages in __netdev_alloc_frag
to deliver fragments used by __netdev_alloc_skb()

Depending on NIC driver and arch being 32 or 64 bit, it allows a page to
be split in several fragments (between 1 and 8), assuming PAGE_SIZE=4096

Switching to bigger pages (32768 bytes for PAGE_SIZE=4096 case) allows :

- Better filling of space (the ending hole overhead is less an issue)

- Less calls to page allocator or accesses to page->_count

- Could allow struct skb_shared_info futures changes without major
  performance impact.

This patch implements a transparent fallback to smaller
pages in case of memory pressure.

It also uses a standard "struct page_frag" instead of a custom one.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

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