Date: Wed, 6 May 2015 08:12:46 +0100
From: Mel Gorman <mgorman@suse.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Waiman Long <waiman.long@hp.com>, Nathan Zimmer <nzimmer@sgi.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Scott Norton <scott.norton@hp.com>,
        Daniel J Blueman <daniel@numascale.com>, Linux-MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/13] Parallel struct page initialisation v4
Message-ID: <20150506071246.GF2462@suse.de>
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 <20150505104514.GC2462@suse.de>
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On Tue, May 05, 2015 at 03:25:49PM -0700, Andrew Morton wrote:
> On Tue, 5 May 2015 23:13:29 +0100 Mel Gorman <mgorman@suse.de> wrote:
> 
> > > Alternatively, the page allocator can go off and synchronously
> > > initialize some pageframes itself.  Keep doing that until the
> > > allocation attempt succeeds.
> > > 
> > 
> > That was rejected during review of earlier attempts at this feature on
> > the grounds that it impacted allocator fast paths. 
> 
> eh?  Changes are only needed on the allocation-attempt-failed path,
> which is slow-path.

We'd have to distinguish between falling back to other zones because the
high zone is artifically exhausted and normal ALLOC_BATCH exhaustion. We'd
also have to avoid falling back to remote nodes prematurely. While I have
not tried an implementation, I expected they would need to be in the fast
paths unless I used jump labels to get around it. I'm going to try altering
when we initialise instead so that it happens earlier.

-- 
Mel Gorman
SUSE Labs
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