linux-kernel - Re: [RFC][PATCH 1/6] count transparent hugepage splits

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Date:	Fri, 04 Feb 2011 13:28:25 -0800
From:	Dave Hansen <dave@...ux.vnet.ibm.com>
To:	Andrea Arcangeli <aarcange@...hat.com>
Cc:	David Rientjes <rientjes@...gle.com>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, Michael J Wolf <mjwolf@...ibm.com>
Subject: Re: [RFC][PATCH 1/6] count transparent hugepage splits

On Fri, 2011-02-04 at 22:18 +0100, Andrea Arcangeli wrote:
> On Thu, Feb 03, 2011 at 01:22:14PM -0800, David Rientjes wrote:
> > i.e. no global locking, but we've accepted the occassional off-by-one 
> > error (even though splitting of hugepages isn't by any means lightning 
> > fast and the overhead of atomic ops would be negligible).
> 
> Agreed losing an increment is not a problem, but in very large systems
> it will become a bottleneck. It's not super urgent, but I think it
> needs to become a per-cpu counter sooner than later (not needed
> immediately but I would appreciate an incremental patch soon to
> address that). 

Seems like something that would be fairly trivial with the existing
count_vm_event() infrastructure.  Any reason not to use that?  I'll be
happy to tack a patch on to my series.

-- Dave

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