Re: [squid-users] Re: [SQU] Squid giving page faults

On Thursday 31 July 2003 04.02, Adam Aube wrote:

> Divide the number of page faults by the "Number of HTTP requests
> received" statistic, then multiply by 100 to get a percentage. Let
> us know what this percentage is - I honestly couldn't say at what
> level one should be concerned.

And it very much depends on the OS used. The use of page faults varies
betwee the OS:es somewhat, where some OS:es uses page faults for all
I/O while some only use page faults in swapping.

What can be said is that if you see that the number of page
faults/second increased significantly at about the time when the
speed of your Squid decreased significantly then you have a shortage
of memory.

The best way to measure if you have a shortage of memory or not is to

a) Comparing the size of your Squid process to the amount of memory
you have available. If you find that Squid is using more than 60% of
the memory then you may want to either add more memory or decrease
the size of Squid (see the Squid FAQ chapter on memory usage).

b) Use of standard system monitoring tools like sar/iostat/vmstat.

ps. The 60% above obviously depends on what else is running on the
same server. 60% is based on the assumption that nothing else
significant runs on the same server (including X if it is a smallish
server).

Regards
Henrik

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