IDS Forum

Re: identify what is allocating memory

Posted By: JACQUES RENAUT
Date: Friday, 28 July 2017, at 4:21 p.m.

In Response To: Re: identify what is allocating memory (Cesar Martins)

original post:

<some stuff deleted>

@Jacques ,

Thank you for your explanation.
Please, can you answer my question below?

If I get the sum of the column totalsize of all lines on 'onstat -g mem'
(Pool+blkpool), should be close value of the used memory for the segments
at 'onstat -g seg' ? (respecting the type of the segment, vitual,
reserved...)
Ask that because the situation I had here the sum of everything at 'onstat
-g mem' was close of 8.3GB and the used segments at 'onstat -g seg' was
~16G (blkused*4096).
Which is to huge discrepancy...

I open an PMR for this, but unfortunately we do not have time enough to
wait a feedback to collect more information and decide bounce and upgrade
the instance since we was into a window for maintanece where this will be
allowed.

Regards
Cesar

Response:

There is a couple things that are missing. First off, in onstat -g seg, if you are using 12.x and your buffer pools are in there own segments of class "B" then the blkused for those segments is not accounted for by a corresponding pool that is reported in onstat -g mem. So if you have buffer pools in their own segments, you would want to no include those blkused counts in your comparison of memory used via the sum of total size from onstat -g mem for pools and block pools and the blkused in onstat -g seg. Second item would be if your server uses VP_MEMORY_CACHE_KB or not. If your server has VP_MEMORY_CACHE_KB = 0 (so it's turned off) then I would expect that the sum of all the total size for pools and block pools in onstat -g mem to equal all of the used blocks portion of onstat -g seg (excluding blkused for segments of class "B"). However, if VP_MEMORY_CACHE_KB is a non-zero value and you don't have it set to STATIC then the size of the vp memory cache can vary and in that case you have to look at onstat -g vpcache to see how much memory each oninit vp has in it's vp cache....in that case then the sum of all blocks in the vp caches + sum of all the total size of all the pools and block pools from onstat -g mem should be roughly the size of the used blocks in onstat -g seg (excluding blkused for class "B" segments).

At least that is what I would expect. I don't know that I'm certain enough to say this is 100% true, but it's my feeling on what I think would be the behavior. I know for sure the buffer pool segment blks are not accounted for in the onstat -g mem and I know for sure blocks in the vpcache are not accounted for in onstat -g mem...I'm just not 100% sure that there isn't anything else that wouldn't be accounted for in the onstat -g mem.

Jacques

Messages In This Thread

• identify what is allocating memory
  Cesar Martins -- Friday, 28 July 2017, at 10:02 a.m.
  • Re: identify what is allocating memory
    Marcus Haarmann -- Friday, 28 July 2017, at 10:13 a.m.
  • Re: identify what is allocating memory
    JACQUES RENAUT -- Friday, 28 July 2017, at 10:21 a.m.
    • Re: identify what is allocating memory
      david@smooth1.co.uk -- Friday, 28 July 2017, at 10:54 a.m.
      • Re: identify what is allocating memory
        JACQUES RENAUT -- Friday, 28 July 2017, at 11:09 a.m.
        • Re: identify what is allocating memory
          Cesar Martins -- Friday, 28 July 2017, at 3:22 p.m.
          • Re: identify what is allocating memory
            JACQUES RENAUT -- Friday, 28 July 2017, at 4:21 p.m.
          • Re: identify what is allocating memory
            BENJAMIN THOMPSON -- Saturday, 29 July 2017, at 3:29 p.m.
            • Re: identify what is allocating memory
              Paul Watson -- Saturday, 29 July 2017, at 3:55 p.m.

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