Re: Slow, persistent memory leak in 2.6.20

[Denys Vlasenko <vda.linux@googlemail.com>]

On Sunday 26 August 2007 17:16, Fred Tyler wrote:
> So, I guess it worked? (I don't know what was supposed to happen, but
> memory usage dropped significantly when I did this.)

If you can reclaim "leaked" memory this way, it means that
you found a bug where cached data is incorrectly kept
in RAM in preference of other data.
(I'm assuming that you do have real problems after some time
of "leaking" memory - you mention that you get swap storms
and eventually machine is dead.)

> However, I'm not sure this staging machine has been up long enough or
> doing enough to exhibit the problem. I can try this on my production
> servers (the ones I provided graphs for) late tonight, but how safe is
> running this command? Does it permanently disable file caching? Do I

Yes, it's safe to do, anytime.

It's just a command to kernel to drop as much of currently
accumulated filesystem cache as it can. It is strictly
a debugging/benchmarking aid.

If you end up needing to do it once in a while to keep your machine
alive, something is definitely wrong.
--
vda