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Re: OT : kernel using 75% of CPU - Summary and last post

From: Jerry C <usidba_at_yahoo.com>
Date: Thu, 30 Aug 2001 07:13:39 -0700
Message-ID: <F001.0037CEDB.20010830070052@fatcity.com>

Hi all,
 

Think we've figured this out, with much help from you guys.
 

I believe the high percentage of kernel CPU was due to the system swapping. I believe the root cause of the swapping was a combination of:
 

a) an SGA that was too large
b) a sort_area_size that was set too
large  (30Mb.)
c) an app that does a *lot* of
sorting
 

I believe each connection from the app
server (there were about 50-55 connections) would eventually grab 30Mb. of sort space in it's PGA. According to Oracle, this memory never gets released to the OS. So, that's 1.5-1.6Gb. of memory that apparently send us over the edge. Since these are persistent connections from an app server, they never disconnect. We greatly reduced the size of the java pool and brought sort_area_size down, which - I think - fixed the problem.
 

Better to have a few disk sorts than have your box start swapping!
 
 

Thanks again!
 
 

- Jerry
 
 
 

----- Original Message -----
From: "Connor McDonald" <<A

href="mailto:hamcdc_at_yahoo.co.uk"><FONT face="Courier New" 
size=2>hamcdc_at_yahoo.co.uk<FONT face="Courier New" 
size=2>>

To: "Multiple recipients of list ORACLE-L" <<FONT face="Courier New"
size=2>ORACLE-L_at_fatcity.com<FONT face="Courier New" size=2>>
Sent: Wednesday, August 29, 2001 5:27
AM
Subject: RE: OT : kernel using 75% of
CPU
> Agreed - and Sun doesn't
handle getting "close to the> edge" at all well imho.  Recently upgraded a db on> (2.6) server from 8.0 to 8.1.6 and it went from> running fine to running like an absolute dog - kernel> thrashing exactly like our initial poster reports...> > ... The problem?> > java_pool_size (and its 20m default).  Once the idiot> (me) remembered to reset this to 32k, performance was> immediately better than even the original 8.0.  Just> an extra 20M freed up (on a 512M box) and miracles> occurred ....> > Cheers>
Connor> >  --- Christopher Spence <<A
href="mailto:cspence_at_FuelSpot.com"><FONT face="Courier New" size=2>cspence_at_FuelSpot.com>
wrote:> > paging and swapping is the first thing that comes to> > mind, look at vmstat.> >  > > I think your question is completely on topic.> >  > > > > "Do not criticize someone until you walked a mile in> > their shoes, that way> > when you criticize them, you are a mile a way and> > have their shoes."> > > > Christopher R. Spence > > Oracle DBA > > Phone: (978) 322-5744 > > Fax:    (707) 885-2275 > > > > Fuelspot
> > 73 Princeton Street > > North, Chelmsford 01863 > 
>   > > > > -----Original Message-----> 
> Sent: Tuesday, August 28, 2001 11:20 AM> > To: Multiple 
recipients of list ORACLE-L> > > > > > Hi there,> >  > > I have a Sun e4500, running Solaris 2.7 and Oracle> > 8.1.7.1.0. Everything> > looks normal from a database perspective, but when I> > run "top" it show the> > kernel being very hog-like:> >  > > load averages: 14.38, 15.18, 15.18> > 07:16:21> > 126 processes: 118 sleeping, 4 running, 4 on cpu> > CPU states:  0.6% idle, 26.6% user, 72.8% kernel, > > 0.0% iowait,  0.0% swap> > Memory: 4096M real, 63M free, 216M swap in use,> > 5310M swap free> >  > >   PID USERNAME THR PRI
NICE  SIZE   RES STATE   TIME>
>    CPU COMMAND> >  2286
oracle     1   0    0 1844M 1814M 
run     9:44> > 13.90% oracle> > 11068 
oracle     1   0    0 2056K 1536K 
cpu0    0:02> >  1.53% top> > 11333 
oracle     1   0    0 1150M 1124M 
cpu1    0:01> >  1.39% oracle> >  

5944 oracle     1  40    0 1820M 1789M
sleep  14:40> >  1.36% oracle> >  4797
root       1  50    0 2112K 
1248K sleep   6:01> >  1.36% top> > 11346 
oracle     1   0    0  

110M   92M cpu0    0:01> >  1.26%
oracle> > 11114 oracle     1  
0    0 1009M  984M cpu1    0:00> 
>  0.66% oracle> > 11157 oracle     
1   0    0 1009M  984M run     

0:00> >  0.63% oracle> > 11368
oracle     1  33    0 1794M 1765M 
sleep   0:00> >  0.29% oracle> > 19558 
oracle     1  60    0 1797M 1751M 

sleep  78:28> >  0.28% oracle> > 19554
oracle     1  60    0 1794M 1751M
sleep  38:05> >  0.20% oracle> > 11366
oracle     1  55    0 1793M 1763M 
sleep   0:00> >  0.19% oracle> > 11292 
oracle     1  26    2 2008K 1424K 
run     0:00> >  0.19% dsql> 

>  > > Any ideas on what I, as a lowly DBA, would be able> > to check? It's a bit out> > of my area and I'm
stumped...> >  > >  > > Thanks!> 
>  > > Jerry> > > > > > > 
>  > > =====> Connor McDonald> <A 

href="http://www.oracledba.co.uk"><FONT face="Courier New" size=2>http://www.oracledba.co.uk
(mirrored at > <FONT
face="Courier New" size=2>http://www.oradba.freeserve.co.uk<FONT 
face="Courier New" size=2>)> > "Some days you're the pigeon, some 
days you're the statue"> > 
____________________________________________________________> Do You 
Yahoo!?> Get your free @yahoo.co.uk address at <A
href="http://mail.yahoo.co.uk"><FONT face="Courier New" 
size=2>http://mail.yahoo.co.uk<FONT face="Courier New" 
size=2>> or your free @yahoo.ie address at <A 
href="http://mail.yahoo.ie"><FONT face="Courier New" 
size=2>http://mail.yahoo.ie> 

-- > Please see the official ORACLE-L FAQ: <A href="http://www.orafaq.com"><FONT face="Courier New" size=2>http://www.orafaq.com>
-- > Author: =?iso-8859-1?q?Connor=20McDonald?=>   INET: <FONT face="Courier New"
size=2>hamcdc_at_yahoo.co.uk>
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