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04-19-2007 04:55 AM
04-19-2007 04:55 AM
IO wait more in sar output
Dear All,
When i ran "sar -u" in our HPUX 11.23 system i found % system CPU is more than % User CPU . As per my knowledge best ratio is 70% (user mode) and 30% (system mode).Kindly go through the attachment for further details ...
These are my doubts
1) What can be the various reasons which can cause increased % system mode operation of CPU than User mode ?
2) Normally if application code is using more system calls this issue may come . But the samecode is running in similary configuredmachine (with same hardware / O.S
configuration ) with out this problem .
Various outputs are attached .Can anyone suggest what casues this problem ?
Vinod
When i ran "sar -u" in our HPUX 11.23 system i found % system CPU is more than % User CPU . As per my knowledge best ratio is 70% (user mode) and 30% (system mode).Kindly go through the attachment for further details ...
These are my doubts
1) What can be the various reasons which can cause increased % system mode operation of CPU than User mode ?
2) Normally if application code is using more system calls this issue may come . But the samecode is running in similary configuredmachine (with same hardware / O.S
configuration ) with out this problem .
Various outputs are attached .Can anyone suggest what casues this problem ?
Vinod
1 REPLY 1
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04-19-2007 05:04 AM
04-19-2007 05:04 AM
Re: IO wait more in sar output
Shalom,
The ratio of user to system totally depends on how the system is being used and what applications you are running. Your attachment indicates this is an Oracle server.
1.) The assumption you make is false, there is no ideal ratio of system to user. A system that has a high user ratio can be one with an extremely efficient OS set up and good applications running on it. Note further I see significant idle time on your system which means its not being pushed very hard.
2.) I challenge as to whether there is a problem based on the available data.
The original "complaint" is that certain ratios on a sar report are not ideal. I normally don't bother looking for problems unless a report indicates an issue, such as excessive I/O or more likely users complain of poor response time.
Memory use is low, swap is being reserved but proceses not swapped out.
I don't see a problem here. Maybe take a larger performance data sample. Here is a link to some nice sar scripts.
http://www.hpux.ws/system.perf.sh
This site will be down from 2-4 p.m. for critical network maintenance, Central time, only the day of this post.
SEP
The ratio of user to system totally depends on how the system is being used and what applications you are running. Your attachment indicates this is an Oracle server.
1.) The assumption you make is false, there is no ideal ratio of system to user. A system that has a high user ratio can be one with an extremely efficient OS set up and good applications running on it. Note further I see significant idle time on your system which means its not being pushed very hard.
2.) I challenge as to whether there is a problem based on the available data.
The original "complaint" is that certain ratios on a sar report are not ideal. I normally don't bother looking for problems unless a report indicates an issue, such as excessive I/O or more likely users complain of poor response time.
Memory use is low, swap is being reserved but proceses not swapped out.
I don't see a problem here. Maybe take a larger performance data sample. Here is a link to some nice sar scripts.
http://www.hpux.ws/system.perf.sh
This site will be down from 2-4 p.m. for critical network maintenance, Central time, only the day of this post.
SEP
Steven E Protter
Owner of ISN Corporation
http://isnamerica.com
http://hpuxconsulting.com
Sponsor: http://hpux.ws
Twitter: http://twitter.com/hpuxlinux
Founder http://newdatacloud.com
Owner of ISN Corporation
http://isnamerica.com
http://hpuxconsulting.com
Sponsor: http://hpux.ws
Twitter: http://twitter.com/hpuxlinux
Founder http://newdatacloud.com
The opinions expressed above are the personal opinions of the authors, not of Hewlett Packard Enterprise. By using this site, you accept the Terms of Use and Rules of Participation.
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