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List:       linux-390
Subject:    Re: How to find a memory leak? cmmflush and iib/wmb
From:       Marcy Cortes <Marcy.D.Cortes () wellsfargo ! com>
Date:       2015-07-21 14:07:56
Message-ID: 1E28C3167790454983C077EBABB037D930581F09 () MSGEXSV21146 ! ent ! wfb ! bank ! corp
[Download RAW message or body]

Maybe?!    I checked one WMB server that has 4G.   It seems to drop roughly 2.5G a \
day.   Not sure how to tell what that is from!



-----Original Message-----
From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Will, Chris
Sent: Tuesday, July 21, 2015 7:02 AM
To: LINUX-390@VM.MARIST.EDU
Subject: Re: [LINUX-390] How to find a memory leak? cmmflush and iib/wmb

Will cmmflush cause WMB or IIB to release memory that may build up over the week in \
the execution groups?

Chris Will

-----Original Message-----
From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Marcy Cortes
Sent: Thursday, July 09, 2015 12:00 PM
To: LINUX-390@VM.MARIST.EDU
Subject: Re: How to find a memory leak?

Easier, but the pages aren't dropped from the zVM side immediately so if you are \
memory constrained there, cmmflush is your friend.


-----Original Message-----
From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Michael \
                MacIsaac
Sent: Thursday, July 09, 2015 8:51 AM
To: LINUX-390@VM.MARIST.EDU
Subject: Re: [LINUX-390] How to find a memory leak?

Tomas,

> I forgot to answer this question: you can drop buffers and cache by
running
> echo 3 > /proc/sys/vm/drop_caches

Nice, even easier. Thanks!

The next question is - can this ever be done by a non-root user? I tried adding \
/bin/echo to /etc/sudoers, but still get an error:

mike@lab153:~ $ sudo /bin/echo 3 > /proc/sys/vm/drop_caches
-bash: /proc/sys/vm/drop_caches: Permission denied



    -Mike

On Thu, Jul 9, 2015 at 11:36 AM, Pavelka, Tomas <Tomas.Pavelka@ca.com>
wrote:

> > Thanks.  I copied and pasted cmmflush and it seems to work nicely
> 
> If I understand it right then you have to look at how cmmflush affects 
> the output of /proc/buddyinfo. If you see non-zero in the last order 
> of slab (i.e. the one with 1MB size) then you are good to run vmcp --buffer=1M.
> Otherwise you may still run into problems even if free -m shows a lot 
> of free memory.
> 
> But I have not tried cmmflush, maybe it will help.
> 
> The way that I was able to reproduce the memory fragmentation problem 
> was by copying large amount of data over SCP to that Linux machine.
> Try that and see if you can reproduce the vmcp --buffer=1M failure.
> 
> Tomas
> 

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