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High page in ratio in vmstat

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Eric Unix
Frequent Advisor

High page in ratio in vmstat

Hello All

My unix box have high page in raito in vmstat output. why ? and how to fix it ?
thanks a lot .

vmstat output ----->
page faults cpu
pi po in sy cs us sy id
209 0 11182 22844 4548 67 8 26
91 0 10911 19320 4503 64 7 29
48 0 10069 23985 3945 54 6 40
24 0 10911 22255 4120 70 8 22
41 0 10411 33238 5588 80 11 8

swapinfo -atm -------------->

Mb Mb Mb PCT
dev 4096 0 4096 0%
dev 28000 2620
reserve - 7278 -7278
total 32096 9898 22198 31%
Look forward
Honored Contributor

Re: High page in ratio in vmstat

A lot of page-ins with no page-outs means the system is reading in a lot of program code and/or data, i.e. doing useful work.

A large number of _page-outs_ would indicate the system needs more memory and actually has to actively use the swap areas.

Your vmstat output indicates your system is idle for about 25% of the time, so your server does not seem to be CPU-bottlenecked.

If the server is performing to your satisfaction, that's fine: you have some CPU capacity in reserve in case the workload increases.

If you are trying to find ways to increase your server's performance, examine the I/O statistics next: maybe your workload needs faster disks and/or network interfaces to get the full use out of your CPU(s).

Steven E. Protter
Exalted Contributor

Re: High page in ratio in vmstat


memory utilization is low. I don't see this as a problem.

For more performance data:

Steven E Protter
Owner of ISN Corporation
Suraj K Sankari
Honored Contributor

Re: High page in ratio in vmstat


Is your box is running slow ?
due to this what is the problem you facing ?


Re: High page in ratio in vmstat

What are the values of max and min for your disk cache? Are you using Oracle with a large SGA?
Emil Velez
Honored Contributor

Re: High page in ratio in vmstat

page ins probably mean that you are starting a lot of new processes. Page ins are normal because UNIX does not load a whole process into memory when it starts. It only loads a small portion of the process then by reference does the rest as page ins.

This should only be the case initially when processes start. With buffer cache set correctly new processes should not need page ins later.

Re: High page in ratio in vmstat

This Means the system is doing its job perfectly

Bill Hassell
Honored Contributor

Re: High page in ratio in vmstat

As Emil states, every process that runs on your system must be paged-in before it can run. So on a busy system with lots of program starts, page-in will very high and should be ignored unless you are not expecting a very high number of program starts (ie, a runaway loop of some sort).

On the other hand, page-out is completely different. This means that there is not enough memory and a portion of some program(s) will be written to the swap area. There can also be some page-outs when your programs use memory mapped files.

On your system, there are no page outs so memory is more than adequate.

Bill Hassell, sysadmin
Eric Unix
Frequent Advisor

Re: High page in ratio in vmstat

Hello Matti

Thanks for you good suggestion.
And, how to get the I/O statistics ?
Please suggest the better command for me.
Thanks a lot.
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