[PATCH] drop note_interrupt() for per-CPU for proper scaling
b60c1f6f · John Hawkes <[email protected]> · 2005-05-27 12:53:00 -07:00
The "unhandled interrupts" catcher, note_interrupt(), increments a global
desc->irq_count and grossly damages scaling of very large systems, e.g.,
>192p ia64 Altix, because of this highly contented cacheline, especially
for timer interrupts. 384p is severely crippled, and 512p is unuseable.
All calls to note_interrupt() can be disabled by booting with "noirqdebug",
but this disables the useful interrupt checking for all interrupts.
I propose eliminating note_interrupt() for all per-CPU interrupts. This
was the behavior of linux-2.6.10 and earlier, but in 2.6.11 a code
restructuring added a call to note_interrupt() for per-CPU interrupts.
Besides, note_interrupt() is a bit racy for concurrent CPU calls anyway, as
the desc->irq_count++ increment isn't atomic (which, if done, would make
scaling even worse).
Signed-off-by: John Hawkes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
- Commit
- b60c1f6ffd88850079ae419aa933ab0eddbd5535
- Parents
- 70ffc71c
Changes
1 files changed · +0 −2
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 06b5a63..436c7d9 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -119,8 +119,6 @@ fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs)
*/
desc->handler->ack(irq);
action_ret = handle_IRQ_event(irq, regs, desc->action);
- if (!noirqdebug)
- note_interrupt(irq, desc, action_ret);
desc->handler->end(irq);
return 1;
}