Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c

[Andi Kleen <andi@firstfloor.org>]

On Tue, Aug 14, 2007 at 02:15:12PM -0700, Christoph Lameter wrote:
> On Tue, 14 Aug 2007, Andi Kleen wrote:
> 
> > > Hmmmm... The spinlock is its own flag.
> > 
> > Yes, but it's not CPU local. Taking the spinlock from another CPU's
> > interrupt handler is perfectly safe, just not from the local CPU.
> > If you use the spinlock as flag you would need to lock out everybody.
> 
> So every spinlock would have an array of chars sized to NR_CPUS and set 
> the flag when the lock is taken?

I was more thinking of a single per cpu flag for all of page reclaim
That keeps it also cache local.

-Andi
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