Re: [RFC] [PATCH] Include LRU in page count

Andrew Morton
2002-09-01T21:53:58Z

Daniel Phillips wrote:
>
> ...
> I'm looking at your spinlock_irq now and thinking the _irq part could
> possibly be avoided. Can you please remind me of the motivation for this -
> was it originally intended to address the same race we've been working on
> here?
>

scalability, mainly. If the CPU holding the lock takes an interrupt,
all the other CPUs get to spin until the handler completes. I measured
a 30% reducton in contention from this.

Not a generally justifiable trick, but this is a heavily-used lock.
All the new games in refill_inactive() are there to minimise the
interrupt-off time.