tree a59ad1118535432b42821b65efe96ac27450c26a
parent 5dff747b7038d10f9c174a1245263fd1c36a644d
author Eric Dumazet <edumazet@google.com> 1348642017 +0000
committer David S. Miller <davem@davemloft.net> 1348788575 -0400

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>