Re: aio stress panic on 2.6.11-mm1

[Andi Kleen]

Arjan van de Ven <arjan@xxxxxxxxxxxxx> writes:

> On Wed, 2005-03-09 at 16:34 +0530, Suparna Bhattacharya wrote:
>> Any sense of how costly it is to use spin_lock_irq's vs spin_lock
>> (across different architectures) ? Isn't rwsem used very widely ?
>
> oh also rwsems aren't used all that much simply because they are quite
> more expensive than regular semaphores, so that you need a HUGE bias in
> reader/writer ratio to make it even worth it...

I agree. I think in fact once Christopher L's lockless page fault fast path
goes in it would be a good idea to reevaluate if mmap_sem should
be really a rwsem and possibly change it back to a normal semaphore
that perhaps gets dropped only on a page cache miss.

-Andi
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/