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: mabi at protonmail.ch
>> To: Ravishankar N <ravishankar at redhat.com>
>> Pranith Kumar Karampuri <pkarampu at redhat.com>, Gluster Users
>> <gluster-users at gluster.org>, Gluster Devel <gluster-devel
at gluster.org>
>>
>> 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: ravishankar at redhat.com
>>> To: Pranith Kumar Karampuri <pkarampu at redhat.com>, mabi
>>> <mabi at protonmail.ch>
>>> Gluster Users <gluster-users at gluster.org>, Gluster Devel
>>> <gluster-devel at gluster.org>
>>>
>>>
>>> On 05/17/2017 11:07 PM, Pranith Kumar Karampuri wrote:
>>>> + gluster-devel
>>>>
>>>> On Wed, May 17, 2017 at 10:50 PM, mabi <mabi at
protonmail.ch
>>>> <mailto: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.
>>>>
>>> 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: ravishankar at redhat.com <mailto:ravishankar
at redhat.com>
>>>>> To: mabi <mabi at protonmail.ch <mailto:mabi at
protonmail.ch>>,
>>>>> Gluster Users <gluster-users at gluster.org
>>>>> <mailto: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 <mailto:mabi at
protonmail.ch>
>>>>>>> To: Gluster Users <gluster-users at
gluster.org>
>>>>>>> <mailto: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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>>>>>> Gluster-users at gluster.org
<mailto:Gluster-users at gluster.org>
>>>>>>
http://lists.gluster.org/mailman/listinfo/gluster-users
>>>>>>
<http://lists.gluster.org/mailman/listinfo/gluster-users>
>>>>>>
>>>> _______________________________________________
Gluster-users
>>>> mailing list Gluster-users at gluster.org
>>>> <mailto:Gluster-users at gluster.org>
>>>> http://lists.gluster.org/mailman/listinfo/gluster-users
>>>>
<http://lists.gluster.org/mailman/listinfo/gluster-users>
>>>>
>>>> --
>>>> Pranith
>>>
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