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authorRavikiran G Thirumalai <kiran@scalex86.org>2007-05-08 03:29:13 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-08 14:15:09 -0400
commite729aa16b168fb202d1a20f936028cb7c2a0278d (patch)
treed0267225ebfadbaa4f55f55c3025597d86ff1c5f /include
parent428e6ce023c5890cfecc8ad10335da3f28dbf893 (diff)
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>
Diffstat (limited to 'include')
-rw-r--r--include/linux/irq.h4
1 files changed, 1 insertions, 3 deletions
diff --git a/include/linux/irq.h b/include/linux/irq.h
index a6899402b522..1695054e8c63 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -147,8 +147,6 @@ struct irq_chip {
147 * @dir: /proc/irq/ procfs entry 147 * @dir: /proc/irq/ procfs entry
148 * @affinity_entry: /proc/irq/smp_affinity procfs entry on SMP 148 * @affinity_entry: /proc/irq/smp_affinity procfs entry on SMP
149 * @name: flow handler name for /proc/interrupts output 149 * @name: flow handler name for /proc/interrupts output
150 *
151 * Pad this out to 32 bytes for cache and indexing reasons.
152 */ 150 */
153struct irq_desc { 151struct irq_desc {
154 irq_flow_handler_t handle_irq; 152 irq_flow_handler_t handle_irq;
@@ -175,7 +173,7 @@ struct irq_desc {
175 struct proc_dir_entry *dir; 173 struct proc_dir_entry *dir;
176#endif 174#endif
177 const char *name; 175 const char *name;
178} ____cacheline_aligned; 176} ____cacheline_internodealigned_in_smp;
179 177
180extern struct irq_desc irq_desc[NR_IRQS]; 178extern struct irq_desc irq_desc[NR_IRQS];
181 179