* NFS write throughput not constant
@ 2016-09-09 5:34 Fu, Yong
2016-09-12 7:04 ` Mkrtchyan, Tigran
0 siblings, 1 reply; 2+ messages in thread
From: Fu, Yong @ 2016-09-09 5:34 UTC (permalink / raw)
To: linux-nfs@vger.kernel.org
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?
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: NFS write throughput not constant
2016-09-09 5:34 NFS write throughput not constant Fu, Yong
@ 2016-09-12 7:04 ` Mkrtchyan, Tigran
0 siblings, 0 replies; 2+ messages in thread
From: Mkrtchyan, Tigran @ 2016-09-12 7:04 UTC (permalink / raw)
To: Fu, Yong; +Cc: linux-nfs
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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