[Gluster-users] high CPU load on all bricks

Sat Feb 9 20:02:08 UTC 2013

            Follow up: still seeing extremely high CPU loads on all bricks
during any file activity. e.g. from top:

            630 root      20   0  319m  85m 2676 R 134.8  0.3   1023:21
glusterfs

26486 root    20   0 1921m  72m 2124 S 41.5   0.2 418:27.29 glusterfsd

The 134.8% CPU is curious reporting (peaks up to 200% or so) but these
readings are typical of any of the eight brick systems in the volume when
either files are being read / written or an application stored in the volume
is in use on any of the systems in the brick. Is this kind of load expected
in an eight-brick 2x replicated volume? When I grabbed the readings above no
files were being accesses but an application file was in use. Is there any
way I can get more detailed performance metrics while in use? 

            Thanks,

            ~Mike C. 

From: gluster-users-bounces at gluster.org
[mailto:gluster-users-bounces at gluster.org] On Behalf Of Joe Julian
Sent: Sunday, February 03, 2013 11:47 AM
To: gluster-users at gluster.org
Subject: Re: [Gluster-users] high CPU load on all bricks

On 02/03/2013 11:22 AM, Michael Colonno wrote:

            Having taken a lot more data it does seem the glusterfsd and
glusterd processes (along with several ksoftirqd) spike up to near 100% on
both client and brick servers during any file transport across the mount.
Thankfully this is short-lived for the most part but I'm wondering if this
is expected behavior or what others have experienced(?) I'm a little
surprised such a large CPU load would be required to move small files and /
or use an application within a Gluster mount point. 

If you're getting ksoftirqd spikes, that sounds like a hardware issue to me.
I never see huge spikes like that on my servers nor clients.

            I wanted to test this against an NFS mount of the same Gluster
volume. I managed to get rstatd installed and running but my attempts to
mount the volume via NFS are met with: 

            mount.nfs: requested NFS version or transport protocol is not
supported

            Relevant line in /etc/fstab:

            node1:/volume    /volume    nfs
defaults,_netdev,vers=3,mountproto=tcp        0 0      

It looks like CentOS 6.x has NFS version 4 built into everything. So a few
questions:

-       Has anyone else noted significant performance differences between a
glusterfs mount and NFS mount for volumes of 8+ bricks? 

-       Is there a straightforward way to make the newer versions of CentOS
play nice with NFS version 3 + Gluster? 

-       Are there any general performance tuning guidelines I can follow to
improve CPU performance? I found a few references to the cache settings but
nothing solid. 

If the consensus is that NFS will not gain anything then I won't waste the
time setting it all up. 

NFS gains you the use of FSCache to cache directories and file stats making
directory listings faster, but it adds overhead decreasing the overall
throughput (from all the reports I've seen).

I would suspect that you have the kernel nfs server running on your servers.
Make sure it's disabled.

Thanks,

~Mike C. 

From: gluster-users-bounces at gluster.org
[mailto:gluster-users-bounces at gluster.org] On Behalf Of Michael Colonno
Sent: Friday, February 01, 2013 4:46 PM
To: gluster-users at gluster.org
Subject: Re: [Gluster-users] high CPU load on all bricks

            Update: after a few hours the CPU usage seems to have dropped
down to a small value. I did not change anything with respect to the
configuration or unmount / stop anything as I wanted to see if this would
persist for a long period of time. Both the client and the self-mounted
bricks are now showing CPU < 1% (as reported by top). Prior to the larger
CPU loads I installed a bunch of software into the volume (~ 5 GB total). Is
this kind a transient behavior - by which I mean larger CPU loads after a
lot of filesystem activity in short time - typical? This is not a problem in
my deployment; I just want to know what to expect in the future and to
complete this thread for future users. If this is expected behavior we can
wrap up this thread. If not then I'll do more digging into the logs on the
client and brick sides. 

            Thanks,

            ~Mike C. 

From: Joe Julian [mailto:joe at julianfamily.org] 
Sent: Friday, February 01, 2013 2:08 PM
To: Michael Colonno; gluster-users at gluster.org
Subject: Re: [Gluster-users] high CPU load on all bricks

Check the client log(s). 

Michael Colonno <mcolonno at stanford.edu> wrote:

            Forgot to mention: on a client system (not a brick) the
glusterfs process is consuming ~ 68% CPU continuously. This is a much less
powerful desktop system so the CPU load can't be compared 1:1 with the
systems comprising the bricks but still very high. So the issue seems to
exist with both glusterfsd and glusterfs processes. 

            Thanks,

            ~Mike C. 

From: gluster-users-bounces at gluster.org
[mailto:gluster-users-bounces at gluster.org] On Behalf Of Michael Colonno
Sent: Friday, February 01, 2013 12:46 PM
To: gluster-users at gluster.org
Subject: [Gluster-users] high CPU load on all bricks

            Gluster gurus ~

            I've deployed and 8-brick (2x replicate) Gluster 3.3.1 volume on
CentOS 6.3 with tcp transport. I was able to build, start, mount, and use
the volume. On each system contributing a brick, however, my CPU usage
(glusterfsd) is hovering around 20% (virtually zero memory usage
thankfully). These are brand new, fairly beefy servers so 20% CPU load is
quite a bit. The deployment is pretty plain with each brick mounting the
volume to itself via a glusterfs mount. I assume this type of CPU usage is
atypically high; is there anything I can do to investigate what's soaking up
CPU and minimize it? Total usable volume size is only about 22 TB (about 45
TB total with 2x replicate). 

            Thanks,

            ~Mike C. 

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