diff options
| author | John Hawkes <hawkes@sgi.com> | 2005-05-27 12:53:00 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-05-28 11:14:00 -0700 |
| commit | b60c1f6ffd88850079ae419aa933ab0eddbd5535 (patch) | |
| tree | d0f12a263ea1fe3b434de6a5d338509e238d46b3 /kernel/irq | |
| parent | 70ffc71c5c42c8ac62d951e80d9799bd5764f2f5 (diff) | |
| download | linux-next-b60c1f6ffd88850079ae419aa933ab0eddbd5535.tar.gz | |
[PATCH] drop note_interrupt() for per-CPU for proper scaling
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 <hawkes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/irq')
| -rw-r--r-- | kernel/irq/handle.c | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c index 06b5a6323998..436c7d93c00a 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; } |