[THIN] Re: High Page Swaps

  • From: "Tim Mangan" <tmangan@xxxxxxxxxxxx>
  • To: <thin@xxxxxxxxxxxxx>
  • Date: Fri, 22 Sep 2006 13:04:21 -0400



First, you should do the following to confirm if this really is a
performance issue.  Page swapping occurs when overall system memory usage
gets high.  But not all page swapping is a performance issue.  A page swap
is counted any time a process tries to access a memory page that is not in
its working set.  This might mean that the page was swapped out to disk and
is no longer in memory and has to be read in "on-demand" (called a hard page
fault).  It might also be a soft page fault, where the memory has been
removed from the working set as part of the page-out procedure but is still
present on a virtual memory page.  With a soft page fault the memory is
immediately restored to the working set with very, very, little overhead.


One should look at the "pages in" counter from the OS to determine the
hard-fault rather than the "page fault" counter which includes both hard and
soft faults.  You can confirm this using whatever management tool you have
handy, including the "performance monitor" that is included in the OS.  Only
if the "pages in" counter is high should you consider it a performance issue
worth concerning yourself with.  In that case you want to look for processes
with high memory use, especially one that keeps growing over time which may
indicate a memory leak bug.


Tim Mangan


From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf
Of Luchette, Jon
Sent: Thursday, September 21, 2006 10:20 AM
To: thin@xxxxxxxxxxxxx
Subject: [THIN] High Page Swaps


Hello -


I am using the advanced load monitor on MF XP FR3 sp4 running win 2k3 sp1
boxes on BL35p hardware booting from SAN.  Every once in a while I notice
that the Page Swaps Rule is maxed out 100% on one or two of my servers when
I check within the CMC.   How would I track down the culprit to try and stop
this from reoccurring?




Jon Luchette 

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