[Beowulf] SWAP management
Lombard, David N
david.n.lombard at intel.com
Fri Dec 12 09:51:51 EST 2003
From: Robert G. Brown; Sent: Friday, December 12, 2003 4:25 AM
> On Thu, 11 Dec 2003, Mark Hahn wrote:
> > > It seems that my Linux OS [RH 7.3 basically, in some cases SuSE
> > > tries to avoid that the percentage of memory used by a single
> > > becomes higher than 60-70 %.
> > I don't believe there is any such heuristic. it wouldn't have
> to do
> > with the distribution, of course, only with the kernel.
> To add to Mark's comment, it is not exactly easy to see what's going
> with a system's memory usage. Using top and/or vmstat for starters --
> vmstat 5 will let you differentiate "swap" events from other paging
> disk activity (possibly associated with applications) while letting
> see memory consumption in real time. top will give you a lovely
> of the active process space that auto-updates ever (interval) seconds.
> If you enter M, it will toggle into a mode where the list is sorted by
> memory consumption instead of run queue (which I find often misses
> problems, or rather flashes them up only rarely). You can then look
> Size (full virtual memory allocation of process) and RSS (space the
> process is actually using in memory at the time) while looking at
> memory and swap usage in the header.
I find that atop is a valuable tool to see what going on in a system,
much better than standard top.
Atop doesn't display inactive processes, so your display isn't clutter
with processes you don't care about, regardless of your sort; atop also
shows the growth of both virtual and resident memory. In addition, atop
also gives a very good look at the system, including cpu, memory, disk,
One final Good Thing, atop can keep raw data in files that you can
"replay" later, allowing you to see a time-history of activity on the
Take a look at ftp://ftp.atcomputing.nl/pub/tools/linux/
David N. Lombard
My comments represent my opinions, not those of Intel.
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