Re: how to know when much page reclamation

[Eugene Teo <eugene.teo@xxxxxxxxxxxxx>]

<quote sender="Ed L Cashin">
> Hi.  I can choose one of two different related things in userland, and
> one takes more physical memory than the other but runs faster.

you mean one memory intensive, one io intensive?

> Looking at the number of free pages in the system doesn't really tell
> me whether memory is "tight" or not.  There could be plenty of pages
> being used for caches, and at the first sign of memory pressure, those
> caches may shrink.
> 
> The best way I can think of to know whether memory is really tight is
> to measure how often shrink_zone is getting called.  (I'm looking at a
> 2.6.0-test11 kernel.)
> 
> I can add some light instrumentation to track the rate at which
> shrink_zone gets called and a system call to make that rate visible to
> userland.  Is there an existing way already in place or a better way
> to know when memory is tight?

cat /proc/vmstat, see pgscan. but the stat is commulative. 

> -- 
> --Ed L Cashin            |   PGP public key:
>   ecashin@xxxxxxx        |   http://noserose.net/e/pgp/
> 
> 
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-- 
Eugene TEO -  <eugeneteo%null!cc!uic!edu> <http://www.anomalistic.org/>
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main(i) { putchar(182623909 >> (i-1) * 5&31|!!(i<7)<<6) && main(++i); }


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