Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e729aa16b168fb202d1a20f936028cb7c2a0278d
Commit: e729aa16b168fb202d1a20f936028cb7c2a0278d
Parent: 428e6ce023c5890cfecc8ad10335da3f28dbf893
Author: Ravikiran G Thirumalai <[EMAIL PROTECTED]>
AuthorDate: Tue May 8 00:29:13 2007 -0700
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue May 8 11:15:09 2007 -0700
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 <[EMAIL PROTECTED]>
Signed-off-by: Shai Fultheim <[EMAIL PROTECTED]>
Cc: "Siddha, Suresh B" <[EMAIL PROTECTED]>
Cc: Ingo Molnar <[EMAIL PROTECTED]>
Cc: Thomas Gleixner <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
include/linux/irq.h | 4 +---
kernel/irq/handle.c | 2 +-
2 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/include/linux/irq.h b/include/linux/irq.h
index a689940..1695054 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -147,8 +147,6 @@ struct irq_chip {
* @dir: /proc/irq/ procfs entry
* @affinity_entry: /proc/irq/smp_affinity procfs entry on SMP
* @name: flow handler name for /proc/interrupts output
- *
- * Pad this out to 32 bytes for cache and indexing reasons.
*/
struct irq_desc {
irq_flow_handler_t handle_irq;
@@ -175,7 +173,7 @@ struct irq_desc {
struct proc_dir_entry *dir;
#endif
const char *name;
-} ____cacheline_aligned;
+} ____cacheline_internodealigned_in_smp;
extern struct irq_desc irq_desc[NR_IRQS];
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index aff1f0f..515ad40 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -48,7 +48,7 @@ handle_bad_irq(unsigned int irq, struct irq_desc *desc)
*
* Controller mappings for all interrupt sources:
*/
-struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned = {
+struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
[0 ... NR_IRQS-1] = {
.status = IRQ_DISABLED,
.chip = &no_irq_chip,
-
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