Pad irq_desc to internode cacheline size
commite729aa16b168fb202d1a20f936028cb7c2a0278d
authorRavikiran G Thirumalai <kiran@scalex86.org>
Tue, 8 May 2007 07:29:13 +0000 (8 00:29 -0700)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Tue, 8 May 2007 18:15:09 +0000 (8 11:15 -0700)
treed0267225ebfadbaa4f55f55c3025597d86ff1c5f
parent428e6ce023c5890cfecc8ad10335da3f28dbf893
Pad irq_desc to internode cacheline size

We noticed a drop in n/w performance due to the irq_desc being cacheline
aligned rather than internode aligned.  We see 50% of expected performance
when two e1000 nics local to two different nodes have consecutive irq
descriptors allocated, due to false sharing.

Note that this patch does away with cacheline padding for the UP case, as
it does not seem useful for UP configurations.

Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: Shai Fultheim <shai@scalex86.org>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/irq.h
kernel/irq/handle.c