commit dd30ac327481f1663b6526fa9fa078569188b7cc
author Horst Hartmann <horsth@linux.vnet.ibm.com> Thu Feb 17 13:13:59 2011 +0100
committer Martin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com> Thu Feb 17 13:13:59 2011 +0100
tree 7e78bdbafc46bf0e70b89857c29c102676693d74
parent 7657e41a0bd16c9d8b3cefe8fd5d6ac3c25ae4bf

[S390] net: provide architecture specific NET_SKB_PAD

NET_SKB_PAD has been increased from 32 to 64 and later to
max(32, L1_CACHE_BYTES). This led to a 25% throughput decrease for
streaming workloads accompanied by a 37% CPU cost increase on s390.
Define a architecture specific NET_SKB_PAD with the old value of 32.

Signed-off-by: Horst Hartmann <horsth@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/cache.h

diff --git a/arch/s390/include/asm/cache.h b/arch/s390/include/asm/cache.h
index 24aafa6..2a30d5a 100644
--- a/arch/s390/include/asm/cache.h
+++ b/arch/s390/include/asm/cache.h
@@ -13,6 +13,7 @@
 
 #define L1_CACHE_BYTES     256
 #define L1_CACHE_SHIFT     8
+#define NET_SKB_PAD	   32
 
 #define __read_mostly __attribute__((__section__(".data..read_mostly")))