On 05/17/2017 11:07 PM, Pranith Kumar Karampuri wrote:
+ gluster-devel
On Wed, May 17, 2017 at 10:50 PM, mabi <[email protected]
<mailto:[email protected]>> wrote:
I don't know exactly what kind of context-switches it was but what
I know is that it is the "cs" number under "system" when you run
vmstat.
Okay, that could be due to the syscalls themselves or pre-emptive
multitasking in case there aren't enough cpu cores. I think the spike in
numbers is due to more users accessing the files at the same time like
you observed, translating into more syscalls. You can try capturing the
gluster volume profile info the next time it occurs and co-relate with
the cs count. If you don't see any negative performance impact, I think
you don't need to be bothered much by the numbers.
HTH,
Ravi
Also I use the percona linux monitoring template for cacti
(https://www.percona.com/doc/percona-monitoring-plugins/LATEST/cacti/linux-templates.html
<https://www.percona.com/doc/percona-monitoring-plugins/LATEST/cacti/linux-templates.html>)
which monitors context switches too. If that's of any use
interrupts where also quite high during that time with peaks up to
50k interrupts.
-------- Original Message --------
Subject: Re: [Gluster-users] 120k context switches on GlsuterFS nodes
Local Time: May 17, 2017 2:37 AM
UTC Time: May 17, 2017 12:37 AM
From: [email protected] <mailto:[email protected]>
To: mabi <[email protected] <mailto:[email protected]>>,
Gluster Users <[email protected]
<mailto:[email protected]>>
On 05/16/2017 11:13 PM, mabi wrote:
Today I even saw up to 400k context switches for around 30
minutes on my two nodes replica... Does anyone else have so high
context switches on their GlusterFS nodes?
I am wondering what is "normal" and if I should be worried...
-------- Original Message --------
Subject: 120k context switches on GlsuterFS nodes
Local Time: May 11, 2017 9:18 PM
UTC Time: May 11, 2017 7:18 PM
From: [email protected] <mailto:[email protected]>
To: Gluster Users <[email protected]>
<mailto:[email protected]>
Hi,
Today I noticed that for around 50 minutes my two GlusterFS
3.8.11 nodes had a very high amount of context switches, around
120k. Usually the average is more around 1k-2k. So I checked
what was happening and there where just more users accessing
(downloading) their files at the same time. These are
directories with typical cloud files, which means files of any
sizes ranging from a few kB to MB and a lot of course.
Now I never saw such a high number in context switches in my
entire life so I wanted to ask if this is normal or to be
expected? I do not find any signs of errors or warnings in any
log files.
What context switch are you referring to (syscalls context-switch
on the bricks?) ? How did you measure this?
-Ravi
My volume is a replicated volume on two nodes with ZFS as
filesystem behind and the volume is mounted using FUSE on the
client (the cloud server). On that cloud server the glusterfs
process was using quite a lot of system CPU but that server
(VM) only has 2 vCPUs so maybe I should increase the number of
vCPUs...
Any ideas or recommendations?
Regards,
M.
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Pranith
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