Messages in this thread | | | Date | Thu, 19 Nov 2009 02:09:09 +0100 (CET) | From | Sven-Haegar Koch <> | Subject | Re: Linux 2.6.31 - very swap-happy with plenty of free RAM |
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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...
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