[Gluster-users] 120k context switches on GlsuterFS nodes

[Pranith Kumar Karampuri]

+ gluster-devel

On Wed, May 17, 2017 at 10:50 PM, mabi <mabi at protonmail.ch> 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.
>
> Also I use the percona linux monitoring template for cacti (
> 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: ravishankar at redhat.com
> To: mabi <mabi at protonmail.ch>, Gluster Users <gluster-users at gluster.org>
>
>
> 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: mabi at protonmail.ch
> To: Gluster Users <gluster-users at gluster.org> <gluster-users at gluster.org>
>
> 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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