[Ocfs2-users] High on buffers and deep on swap

[Alexei_Roudnev]

Did you run slabtop ? It can show unreleased buffers in the system.

  ----- Original Message ----- 
  From: Luis Freitas 
  To: Alexei_Roudnev ; Brian Sieler ; ocfs2-users at oss.oracle.com 
  Sent: Monday, April 09, 2007 2:29 PM
  Subject: Re: [Ocfs2-users] High on buffers and deep on swap


  Alexei,

    Yes, it seems to have no effect, which too is very strange. On 2.4 vm.freepages had a very easy to notice effect.

     There are other people having problems with buffers not being released on the list and some of them are forcing the kernel cache to be flushed with:

  echo 3 > /proc/sys/vm/drop_caches

      But I dont see this parameter on RHAS 4.0.

       Also, to be fair this seems to be a generic VM issue, I see this on servers that are not running ocfs2 too. And I only see this behavior on machines with more than 2Gb of memory.

  Regards,
  Luis

  Regards,
  Luis

  Alexei_Roudnev <Alexei_Roudnev at exigengroup.com> wrote:
    Did you tried vm.swappiness parameter?

    (/proc/sys/vm/swappiness)

      ----- 
      Original Message ----- 
      From: Brian Sieler 
      To: 'Luis Freitas' ; ocfs2-users at oss.oracle.com 
      Sent: Sunday, April 08, 2007 10:52 PM
      Subject: RE: [Ocfs2-users] High on buffers and deep on swap


      Luis, yes I am experiencing what appears to be a similar problem you are describing. See my post from just a few minutes ago on another thread.
       
      I run a 2-node cluster with OCFS2/RAC on 2.6.9-34.0.2.ELsmp (RHEL 4.0) as well.
       
                   total       used       free     shared    buffers     cached
      Mem:       4044496    4005516      38980          0      34108    2236636
      -/+ buffers/cache:    1734772    2309724
      Swap:      2097144     648244    1448900
       
      If you've uncovered anything since posting this message, please pass it along?
       

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      From: ocfs2-users-bounces at oss.oracle.com [mailto:ocfs2-users-bounces at oss.oracle.com] On Behalf Of Luis Freitas
      Sent: Friday, February 23, 2007 5:32 PM
      To: ocfs2-users at oss.oracle.com
      Subject: [Ocfs2-users] High on buffers and deep on swap
       
      Hi,
       
         This is a bit off topic, hope there is not a problem.
       
         Anyone out there experiencing high swapping with the kernel retaining a large amount of buffers? This used to be a problem on 2.4, and I usually changed /proc/sys/vm/freepages to fix it. But on 2.6 this parameter no longer exists.
       
          One of the servers here is holding over 3.5Gb of cache even when using over 700Mb of swap, and free memory is always low.
       
      [oracle at br001sv0432 ~]$ free
                   total       used       free     shared    buffers     cached
      Mem:       5190736    4810880     379856          0     143032    3583868
      -/+ buffers/cache:    1083980    4106756
      Swap:      2048248     723064    1325184
      [oracle at br001sv0432 ~]$
         I am tuning /proc/sys/vm/swappiness, but this seems to have no effect at all. Changed from 60 to 10 and seems to have no effect. The server runs Oracle RAC with OCFS2.
       
      Regards,
      Luis
       
       
        

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