Re: Drop caches - is this safe behavior?

[mike <mike503@gmail.com>]

On 8/23/07, Chris Snook <csnook@redhat.com> wrote:
> I think the caches you had in mind were the ones that would be dropped
> by echoing '1' into /proc/sys/vm/drop_caches, not the ones that would be
> dropped by echoing '2' into it.  If you were dropping pagecache every
> five minutes, it would kill your performance as you described.  As for
> the question of safety, '3' should also be safe, but terrible for
> performance, as it does all the harm of '1', plus some.

actually right now the performance seems to be good - using "2"

i'm willing to try "1" as well, as well as try the cache pressure one.
i don't really know what caches i am clearing, but it seems that i get
bottlenecked by something. restarting my webserver/php engines usually
clears it up, so it seems like it is a buildup of something - and it
always seems to be when memory is tight...

> I'm not familiar with the "atsar" implementation, but it appears to be
> an alternate implementation of the same thing.  It's an excellent tool
> for long-term workload profiling.

actually, this might be a better method - is there any way to view the
contents of the cache? or figure out what exactly is sitting in
there/why my machine thinks it needs to cache 2 gigs of files so
quickly?

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