On 05/22/17 10:27, mabi wrote:
Sorry for posting again but I was really wondering if it is somehow
possible to tune gluster in order to make better use of all my cores
(see below for the details). I suspect that is the reason for the high
sporadic context switches I have been experiencing.
Cheers!
In theory, more clients and more diverse filesets.
The only way to know would be for you to analyze the traffic pattern
and/or profile gluster on your server. There's never some magic "tune
software X to operate more efficiently" setting, or else it would be the
default (except for the "turbo" button back in the early PC clone days).
-------- Original Message --------
Subject: Re: [Gluster-users] 120k context switches on GlsuterFS nodes
Local Time: May 18, 2017 8:43 PM
UTC Time: May 18, 2017 6:43 PM
From: [email protected]
To: Ravishankar N <[email protected]>
Pranith Kumar Karampuri <[email protected]>, Gluster Users
<[email protected]>, Gluster Devel <[email protected]>
I have a single Intel Xeon CPU E5-2620 v3 @ 2.40GHz in each nodes and
this one has 6 cores and 12 threads. I thought this would be enough
for GlusterFS. When I check my CPU graphs everything is pretty much
idle and there is hardly any peeks at all on the CPU. During the very
high context switch my CPU graphs shows the following:
1 thread was 100% busy in CPU user
1 thread was 100% busy in CPU system
leaving actually 10 other threads out of the total of 12 threads
unused...
Is there maybe any performance tuning parameters I need to configure
in order to make a better use of my CPU cores or threads?
-------- Original Message --------
Subject: Re: [Gluster-users] 120k context switches on GlsuterFS nodes
Local Time: May 18, 2017 7:03 AM
UTC Time: May 18, 2017 5:03 AM
From: [email protected]
To: Pranith Kumar Karampuri <[email protected]>, mabi
<[email protected]>
Gluster Users <[email protected]>, Gluster Devel
<[email protected]>
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.
_______________________________________________
Gluster-users mailing list
[email protected] <mailto:[email protected]>
http://lists.gluster.org/mailman/listinfo/gluster-users
<http://lists.gluster.org/mailman/listinfo/gluster-users>
_______________________________________________ Gluster-users
mailing list [email protected]
<mailto:[email protected]>
http://lists.gluster.org/mailman/listinfo/gluster-users
<http://lists.gluster.org/mailman/listinfo/gluster-users>
--
Pranith
_______________________________________________
Gluster-users mailing list
[email protected]
http://lists.gluster.org/mailman/listinfo/gluster-users
_______________________________________________
Gluster-users mailing list
[email protected]
http://lists.gluster.org/mailman/listinfo/gluster-users
