From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: linux-kernel@vger.kernel.org, tim.c.chen@linux.intel.com,
linux-mm@kvack.org, Andi Kleen <ak@linux.intel.com>,
aarcange@redhat.com
Subject: Re: [PATCH 2/2] huge-memory: Use fast mm counters for transparent huge pages
Date: Mon, 09 Apr 2012 16:53:25 +0900 [thread overview]
Message-ID: <4F829575.4020704@jp.fujitsu.com> (raw)
In-Reply-To: <1333202997-19550-3-git-send-email-andi@firstfloor.org>
(2012/03/31 23:09), Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> We found that the mm struct anon page counter cache line is much hotter
> with transparent huge pages compared to small pages.
>
> Small pages use a special fast counter mechanism in task_struct, but huge pages
> didn't. The huge pages are larger than the normal 64 entry threshold for the
> fast counter, so it cannot be directly used. Use a new special counter for huge
> pages to handle them efficiently.
>
> Any users just calculate the correct total.
>
> The only special case is transferring the large page count to small pages
> when splitting. I put it somewhat arbitarily into the tricky split
> sequence. Some review on this part is appreciated.
>
> [An alternative would be to not do that, but that could lead to
> negative counters. These should still give the correct result]
>
> Contains a fix for a problem found by Andrea in review.
>
> Cc: aarcange@redhat.com
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
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prev parent reply other threads:[~2012-04-09 7:55 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-31 14:09 Huge page counter speedup complete Andi Kleen
2012-03-31 14:09 ` [PATCH 1/2] mm: Allow using fast mm counters from other files Andi Kleen
2012-04-09 7:50 ` KAMEZAWA Hiroyuki
2012-03-31 14:09 ` [PATCH 2/2] huge-memory: Use fast mm counters for transparent huge pages Andi Kleen
2012-04-09 7:53 ` KAMEZAWA Hiroyuki [this message]
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