From: "Mkrtchyan, Tigran" <tigran.mkrtchyan@desy.de>
To: "Fu, Yong" <yong.fu@intel.com>
Cc: linux-nfs@vger.kernel.org
Subject: Re: NFS write throughput not constant
Date: Mon, 12 Sep 2016 09:04:33 +0200 (CEST) [thread overview]
Message-ID: <1919782444.9045061.1473663873082.JavaMail.zimbra@desy.de> (raw)
In-Reply-To: <E55525BD360D9249AC15FA039225DF5F2F2481A0@SHSMSX101.ccr.corp.intel.com>
Can be related to flushing of dirty pages.
How much memory do you have on the clients?
You can play with vm.dirty_background_bytes
kernel parameter to get better performance.
Linux default is 10% of the RAM
(vm.dirty_background_ratio ), which can produce
spikes on IO if too much data accumulated in
fs cache, while you, probably, smooth continues
writing.
Tigran.
----- Original Message -----
> From: "Fu, Yong" <yong.fu@intel.com>
> To: linux-nfs@vger.kernel.org
> Sent: Friday, September 9, 2016 7:34:54 AM
> Subject: NFS write throughput not constant
> Hi,
> I have some test on 10Gbe against NFS-based storage recently, and found the
> throughput of writing was not constant, the performance of writing drop down
> periodically.
> My nfs client(version 3 and version 4 all tried) resident CentOS
> 6.6(2.6.32-504.el6.x86_64), NFS server is OpenMediaVault(5 ssd with stripe)
>
> On a single mount point(or single nfs client), the avg throughput only can reach
> 430 MB/s, and two nfs clients aggregation can reach 700 MB/s, I can see there
> is periodical drop of network traffic graph both client and server side, and I
> am sure it's a nfs issue by lots of other tests.
>
> I also found the nfs client commit procedure happened at the time that writing
> performance also dropped, and I have read B7
> section(http://nfs.sourceforge.net) and think the relationship between them,
> but no many ideas, can someone help me pinpoint the root cause of this issue?
>
> --
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prev parent reply other threads:[~2016-09-12 7:04 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-09 5:34 NFS write throughput not constant Fu, Yong
2016-09-12 7:04 ` Mkrtchyan, Tigran [this message]
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