ZFS performance degradation over time

Garrett Moore garrettmoore at gmail.com
Tue Jan 19 16:40:52 UTC 2010

I've been watching my memory usage and I have no idea what is consuming
memory as 'Active'.

Last night I had around 6500MB 'Active' again, 1500MB Wired, no inact, ~30MB
buf, no free, and ~100MB swap used. My performance copying ZFS->ZFS was
again slow (<1MB/s). I tried killing rTorrent and no significant amount of
memory was reclaimed - maybe 100MB. `ps aux` showed no processes using any
significant amount of memory, and I was definitely nowhere near 6500MB

I tried running the perl oneliner again to hog a bunch of memory, and almost
all of the Active memory was IMMEDIATELY marked as Free, and my performance
was excellent again.

I'm not sure what in userland could be causing the issue. The only things
I've installed are rTorrent, lighttpd, samba, smartmontools, vim, bash,
Python, Perl, and SABNZBd. There is nothing that *should* be consuming any
serious amount of memory.

On Mon, Jan 18, 2010 at 11:29 AM, Norbert Papke <npapke at acm.org> wrote:

> On January 17, 2010, Garrett Moore wrote:
> > I upgraded my system to 8GB of ram to see if that would help. It hasn't
> >  made much of a difference. After having rTorrent running for a while, my
> >  performance again tanked. Around 6.5GB of memory was showing as 'Active'
> >  according to top.
> 6.5GB of "active" memory seems to imply that a user process is growing or a
> large number of user processes are being created.  I would expect ZFS's
> cache
> to increase the size of "wired" memory.
> Sorry, I have not followed this thread closely.  Are you sure that the
> degradation is ZFS related?  Could it be caused by, for instance, a
> userland
> memory leak?  What happens to active memory when you restart rtorrent?
> Cheers,
> -- Norbert Papke.
>   npapke at acm.org
> http://saveournet.ca
> Protecting your Internet's level playing field
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