Very high memory page fault rate.

[Gulam Mohiuddin]

One of our HP-UX 11i server showing very high memory page fault in Glance.

Any idea what is going wrong and any tuning recommendations.

This server has PeopleSoft application Server Tuxedu running on it.

Page Faults 4554 428865952

Thanks,

Gulam.

[Steven E. Protter · Accepted solution]

Page faults are part of the normal operation of HP-9000 servers. Your actual pageing rate or swap rate is of more concern.

That does not seem to be very serious.

If overall system performance is reasonable, I would not worry much. I'm attaching some data collection scripts in case you want more data.

SEP

[Sridhar Bhaskarla]

Hi Gulam,

The word 'fault' generally triggers alarms. Well, in this case it's a mere misnomer rather than a problem. When a process tries to execute code in a memory page that is not available in memory, then it does a 'page fault' and brings (pages in) from the disk.

On the other hand, if the page was previously pushed (page out) to 'swap' due to memory pressure then it brings (pages in) it from the swap area. However, since the system is already low on memory, in order to accommodate the additional pages, it has to free up the memory by 'paging out' a least active page.

You should be worried in the second case. So I suggest you to concentrate more on 'pageouts' rather than 'page faults'.

-Sri

[Sยภเl Kย๓คг]

Gulam Mohiuddin
Page fault is normal in all the machines which deals with vritual memory and paging.
As far as HPUX is concerned the rate which u have given s not so serius.If page faults increases the following factors to be considred else System performance will be poor
1.How much physical memory is installed,is it suffient for your operations.
2.What is the current Physical memory utilization.
3.How much free memory is available.
4.Which process is holding more memory.
5.Tune the kernal such a way to remove the unused device drivers like..

Look at kernal tuning for further details
regards
SK