From: Stefan Priebe - Profihost AG <s.priebe@profihost.ag>
To: Zhu Yanhai <zhu.yanhai@gmail.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>,
Pekka Enberg <penberg@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mel@csn.ul.ie>, Jens Axboe <jaxboe@fusionio.com>,
Linux Netdev List <netdev@vger.kernel.org>
Subject: Re: slow performance on disk/network i/o full speed after drop_caches
Date: Fri, 26 Aug 2011 08:18:01 +0200 [thread overview]
Message-ID: <4E573A99.4060309@profihost.ag> (raw)
In-Reply-To: <CAC8teKXqZktBK7+GbLgHn-2k+zjjf8uieRM_q_V7JK7ePAk9Lg@mail.gmail.com>
Yanhai,
> Stefan, is your zone_reclaim_mode enabled? try 'cat
> /proc/sys/vm/zone_reclaim_mode',
> and echo 0 to it to disable.
you're abssolutely corect zone_reclaim_mode is on - but why?
There must be some linux software which switches it on.
~# grep 'zone_reclaim_mode' /etc/sysctl.* -r -i
~#
also
~# grep 'zone_reclaim_mode' /etc/sysctl.* -r -i
~#
tells us nothing.
I've then read this:
"zone_reclaim_mode is set during bootup to 1 if it is determined that
pages from remote zones will cause a measurable performance reduction.
The page allocator will then reclaim easily reusable pages (those page
cache pages that are currently not used) before allocating off node pages."
Why does the kernel do that here in our case on these machines.
Stefan
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next prev parent reply other threads:[~2011-08-26 6:18 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4E5494D4.1050605@profihost.ag>
2011-08-24 6:20 ` slow performance on disk/network i/o full speed after drop_caches Pekka Enberg
2011-08-24 9:01 ` Stefan Priebe - Profihost AG
2011-08-24 9:33 ` Wu Fengguang
2011-08-25 9:00 ` Stefan Priebe - Profihost AG
2011-08-26 2:16 ` Wu Fengguang
2011-08-26 2:54 ` Stefan Priebe - Profihost AG
2011-08-26 3:03 ` Wu Fengguang
2011-08-26 3:13 ` Stefan Priebe
2011-08-26 3:26 ` Wu Fengguang
2011-08-26 3:30 ` Zhu Yanhai
2011-08-26 6:18 ` Stefan Priebe - Profihost AG [this message]
2011-08-31 7:11 ` Stefan Priebe - Profihost AG
2011-09-01 4:14 ` Wu Fengguang
2011-09-01 5:41 ` Stefan Priebe - Profihost AG
2011-09-01 12:57 ` Mel Gorman
2011-08-24 9:32 ` Wu Fengguang
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