lkml.org 
[lkml]   [2009]   [Nov]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Linux 2.6.31 - very swap-happy with plenty of free RAM
On Wed, 18 Nov 2009, Dan Merillat wrote:

> On Wed, Nov 18, 2009 at 4:45 PM, Tomasz Chmielewski <mangoo@wpkg.org> wrote:
>
> > I have a pretty powerful desktop machine with 8 GB RAM, fast disks with
> > RAID-1 etc.
>
> > Every 10 minutes or so, machine is really unresponsive, load jumps to 10 or
> > 20. Mouse pointer jumps, it's impossible to change between windows etc.
>
> This is the type of hefty workstation many of the core developers
> have, running similar workloads, so I'm somewhat surprised that the
> default VM settings have this kind of issue.
>
> > Do a "swapoff -a", and everything is snappy and responsive as it should,
> > there are no more lags.
>
> Yes, that's my exact finding.
>
> Is this weird IO storm happening for anyone else with plenty of memory
> (for their taskload?)

For me it happend on my laptop. 3gb RAM, and a 1gb VMWare Windows-XP
instance running, plus the usual like firefox, thunderbird, kde4.

Without running vmware it did not happen. And since I have now disabled
barriers on the xfs /home partition (on luks crypto lvm) it also does
not happen anymore.

The machine is currently 300mb in swap, together with >2gb shown by free
as cached - as I just copied 10gb around nothing I worry about.

For me when it happened it looked like when a big bunch of data is to
be commited to disk xfs seeks between superblock/journal and data
and syncs/waits between each step - reducing the write speed of the
disk from the normal >20mb/s to less than 2mb/s and also delaying all
other disk-accesses in the meantime.

c'ya
sven

ps: I know with disabling barriers I sacrifice some data safety, but
better a usable and fast system than everything ultra-safe and
slow - for safety in suche rare case there is a backup.

--
The lights are fading out, once more...


\
 
 \ /
  Last update: 2009-11-19 02:11    [W:1.174 / U:0.012 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site