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Hey guys,
I need to monitor a program's memory use and to see if any page swapping occurs. Monitoring memory use is easy, but I'm not quite sure how to monitor to see if any swapping occurs.
Is there a way to do this without using auxiliary software?
There is /proc/meminfo or some such, which I believe has paging info.
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Mats
That's great! So I looked in there and found (I cut each down a bit for readability):
I also used vmstat and got:Quote:
Buffers:
Cached:
SwapCached:
Active:
Inactive:
SwapTotal:
SwapFree:
Dirty:
Writeback:
AnonPages:
Mapped:
Slab:
PageTables:
VmallocTotal:
VmallocUsed:
VmallocChunk:
Now, from vmstat, I assume the 'pages swapped in' and 'pages swapped out' sections are where I'd start looking. I have a few questions:Quote:
free memory
buffer memory
96780 swap cache
524280 total swap
1664 used swap
522616 free swap
825797 pages paged in
813650 pages paged out
135091 pages swapped in
41812 pages swapped out
interrupts
CPU context switches
forks
- Is there a way to start these tools to measure from the beginning of a program's execution? It seems like these tools have been measuring and gathering statistics from when they are booted capturing data from all activity on the processor.
- Are the 'pages in' and 'pages out' parameters measured in single pages?
- Both tools have a parameter to measure 'swap'. I Googled swap and I get the gist of it - but how is it different than a page? For example, is 'used swap' the amount of memory used in a single page? And is 'free swap' the amount of page memory left in the page before it needs to be swapped?
Thanks again!
I'm pretty sure "used swap" and "free swap" is the amount of space used/free on the swap partition. vmstat man-page or some other such documentation should give you a clue as to what the unit is, either kilobytes or pages.
pages out and pages in would tell you how many pages has been swapped out and in respectively (if it's not modified, the same page may be swapped in several times without being swapped out - since there is no reason to swap out a page that isn't modified - and pages may of course be swapped out and never be swapped back in ever again, if the code is doing the "right" things).
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Mats
Are the "si" and "so" fields which "vmstat -n 1" generates not sufficient?
Gotcha. Now, is there a way to start these statistics from 0 when I start my program?
Well, there are probably many things that are sufficient. However, I'm new to this so I may not know them.Quote:
Originally Posted by brewbuck
The "si" and "so" fields do look to be exactly what I want.
I was using "vmstat -s" to format it so its easier to view.
It looks like "vmstat -n 1" starts all values from 0 and continues to update forever? If so, that is exactly what I'm looking for.
Thanks!
I don't think vmstat is cumulative. It just displays the number of events per update cycle. You could do some light post-processing on it to turn it into a cumulative report.
EDIT: I didn't mean to be harsh in my previous post, just genuinely curious whether vmstat could do what you want, since it's a lot easier.
No offense taken at all. Vmstat is exactly what I was looking for.Quote:
Originally Posted by brewbuck
Thanks!
really it's nice information about page swapping.Thanks for sharing
Depending on your needs mate, check out Htop which I like a lot more than Top....