From: Greg KH <greg@kroah.com>
To: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: gregkh@suse.de, cascardo@holoscopio.com,
dan.magenheimer@oracle.com, rdunlap@xenotime.net,
devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] staging: zcache: reduce tmem bucket lock contention
Date: Mon, 3 Oct 2011 16:06:32 -0700 [thread overview]
Message-ID: <20111003230632.GA12719@kroah.com> (raw)
In-Reply-To: <1317306746-27072-1-git-send-email-sjenning@linux.vnet.ibm.com>
On Thu, Sep 29, 2011 at 09:32:26AM -0500, Seth Jennings wrote:
> tmem uses hash buckets each with their own rbtree and lock to
> quickly lookup tmem objects. tmem has TMEM_HASH_BUCKETS (256)
> buckets per pool. However, because of the way the tmem_oid is
> generated for frontswap pages, only 16 unique tmem_oids are being
> generated, resulting in only 16 of the 256 buckets being used.
> This cause high lock contention for the per bucket locks.
>
> This patch changes SWIZ_BITS to include more bits of the offset.
> The result is that all 256 hash buckets are potentially used resulting in a
> 95% drop in hash bucket lock contention.
This patch is somehow corrupted and can't be applied, care to resend it
with Dan's acked-by so that I can apply it?
thanks,
greg k-h
next prev parent reply other threads:[~2011-10-03 23:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-29 14:32 [PATCH] staging: zcache: reduce tmem bucket lock contention Seth Jennings
2011-10-03 18:51 ` Dan Magenheimer
2011-10-03 23:06 ` Greg KH [this message]
2011-10-04 13:21 ` Seth Jennings
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