net: NET_SKB_PAD should depend on L1_CACHE_BYTES
authorEric Dumazet <eric.dumazet@gmail.com>
Wed, 16 Jun 2010 01:16:43 +0000 (18:16 -0700)
committerDavid S. Miller <davem@davemloft.net>
Wed, 16 Jun 2010 01:16:43 +0000 (18:16 -0700)
commit5933dd2f028cdcbb4b3169dca594324704ba10ae
treec49d33589cf1ee2047ed4aa00f700e7ddb090447
parenta95d8c88bea0c93505e1d143d075f112be2b25e3
net: NET_SKB_PAD should depend on L1_CACHE_BYTES

In old kernels, NET_SKB_PAD was defined to 16.

Then commit d6301d3dd1c2 (net: Increase default NET_SKB_PAD to 32), and
commit 18e8c134f4e9 (net: Increase NET_SKB_PAD to 64 bytes) increased it
to 64.

While first patch was governed by network stack needs, second was more
driven by performance issues on current hardware. Real intent was to
align data on a cache line boundary.

So use max(32, L1_CACHE_BYTES) instead of 64, to be more generic.

Remove microblaze and powerpc own NET_SKB_PAD definitions.

Thanks to Alexander Duyck and David Miller for their comments.

Suggested-by: David Miller <davem@davemloft.net>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
arch/microblaze/include/asm/system.h
arch/powerpc/include/asm/system.h
include/linux/skbuff.h