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Virtual Memory tuning

Rafi Moor
Occasional Visitor

Virtual Memory tuning

I am trying to tune Tru64 system for a 3rd party application that seems to map its input files to virtual memory and access (read) them sequentially.
My questions are:

Does the kernel parameter vm_max_rdpgio_kluster affect also mapped files regions page-in? (In the documentation they only refer anonymous memory.)

What is the algorithm for the number of pages that are swapped-in when a page-fault occurs?

Thanks

Rafi Moor
2 REPLIES
Manish PATHAK_2
Regular Advisor

Re: Virtual Memory tuning

It happens almost with all the processes,i will suggest you to monitor your VM usage and also monitor the iostat and per process requirement.

What is the swap you are using on your system.

Regards
Manish
Rafi Moor
Occasional Visitor

Re: Virtual Memory tuning

Thank you Manish,

Naturally I did monitor the systemâ s virtual memory. The picture is like that: There is a lot of free memory, a lot of free swap, zero page-out, quite a bit of page-in and page-faults. The processors spend 40-50% in system mode. I assume this is due to heavy page-in from the mapped data files (I am not talking about text regions).
What I want to do is to make the system map more pages for every page-fault. Since the mapped files are accessed sequentially, this might reduce page-faults.
I know mapped files are loaded to the UBC in chunks of ubc_kluster_cnt pages at a time, but there is still short fault for every page that is not in the active/inactive lists.

I am still waiting for answers to my questions.


Thanks
Rafi