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

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Date:	Mon, 15 Jun 2009 08:46:53 +0200
From:	Nick Piggin <npiggin@...e.de>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:	Christoph Lameter <cl@...ux-foundation.org>,
	Pekka J Enberg <penberg@...helsinki.fi>,
	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, kamezawa.hiroyu@...fujitsu.com,
	lizf@...fujitsu.com, mingo@...e.hu, yinghai@...nel.org
Subject: Re: [GIT PULL v2] Early SLAB fixes for 2.6.31

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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