Re: [GIT PULL v2] Early SLAB fixes for 2.6.31

From: Nick Piggin
Date: Mon Jun 15 2009 - 02:47:12 EST


On Sat, Jun 13, 2009 at 07:46:03AM +1000, Benjamin Herrenschmidt wrote:
>
> > Adds code to hot code path.
>
> A single mask which should be mostly in the noise...

Cacheline load. Yes it will be in the noise. Like all other slowdowns
that get merged ;)


> > The allocators mask flags passed to the page allocator through
> > GFP_RECLAIM_MASK|GFP_CONSTRAINT_MASK. This is done outside of the critical
> > code paths.
> >
> > The might_sleep issues may be fixed by adding another check to
> > __might_sleep().
>
> That is not enough because slab and slub explicitely re-enable
> interrupts when __GFP_WAIT is set, which is the problem we need to solve
> in the first place, so we need to do the masking there.
>
> Cheers,
> Ben.
>
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