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Date: Fri, 03 Nov 2006 08:32:13 -0200
From: creimer@brturbo.com.br
Subject: Context switch storm
To: pgsql-performance@postgresql.org
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Hi,
 
We've migrated one of our servers from pg 7.4 to 8.1 and from times to times (4 hours) the server start doing a lot of context switching and all transactions become very slow.
 
The average context switching for this server as vmstat shows is 1 but when the problem occurs it goes to 250000.
 
CPU and memory usage are ok.
 
What is producing this context switching storms?
 
It is a box with 16GB RAM and 4 XEON processors running RedHat Enterprise Linux AS.
 
Should I disable Hyperthreading?
 
Thank you in advance!
 
Reimer

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<DIV>
<DIV><FONT size=+0><SPAN class=453542615-02112006>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006>Hi,</SPAN></FONT></DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006>We've migrated one of our servers from pg 7.4 to 8.1 and from times to times (4 hours) the server start doing a lot of context switching and all transactions become very slow.</SPAN></FONT></DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006>The average context switching for this server as vmstat shows is 1 but when the problem occurs it goes to 250000.</SPAN></FONT></DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006>CPU and memory usage are ok.</SPAN></FONT></DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006>What is producing this context switching storms?</SPAN></FONT></DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006>It is a box with 16GB RAM and 4 XEON&nbsp;processors running RedHat Enterprise Linux AS.</SPAN></FONT></DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006>Should I disable Hyperthreading?</SPAN></FONT></DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006>Thank you in advance!</SPAN></FONT></DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=Tahoma size=2><SPAN class=497030905-01112006><SPAN class=453542615-02112006>Reimer</SPAN></SPAN></FONT></DIV></SPAN></FONT></DIV></DIV>

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