Re: distributed batch processing
On Wed, May 11, 2005 at 06:12:20PM -0700, Dale Southard wrote:
>
> It's probably also worth looking at the maui scheduler (which
> runs on top of torque or other batch systems). Someone wiser
> than I should probably browse the licenses at
> www.clusterresources.com to verify that torque and/or maui
> meet the Debian standards before any work is started.
>
I've heard rumors of people plugging maui into SGE as well, but have
never seen a writeup of it. My guess is it's not worth the work versus
switching to PBS* if you really need maui. As I understand maui, it's best
when you have large parallel jobs (say 128 nodes of a 512 node cluster),
which it handles by reserving those blocks of nodes for the maximum expected
runtime. To do that though there have to be time limits on all jobs, else
maui schedules things infinitely far away. If jobs finish early, or there
are gaps between scheduled runs, smaller jobs can backfill the schedule to
increase utilization. Jobs that don't finish on time get killed.
It's always been a complex solution for a problem I've never actually
faced. Few people (3, only 1 actually running) in my cluster are writing
parallel code at all, most don't know or don't care how long their programs
will run (Monte Carlo and statistics tend to be like that). They just have
lots of independent serial jobs to run.
In contrast, SGE has a much simpler pair of schedulers (FIFO and
user-sort from DQS). It also has subordinate queues, which work really well
for suspending non-owner jobs (if parts of the cluster "belong" to certain
users) and for long jobs (suspend whenever something else wants to run) and
test/interactive jobs (higher priority, suspend everything lower, very
limited runtimes). A stack of low priority serial jobs make getting 100%
utilization easy. Subordinating part of a parallel job tends to be very
non-productive though (making the rest of the job wait), so parallel jobs
need to run in the higher priority queues to avoid idling large parts of the
cluster.
On Thu, May 12, 2005 at 01:46:24AM +0000, Andrew M.A. Cater wrote:
> Debian Wiki on licence texts - OpenPBS and Torque both non-free.
> (Though this may not be authoritative, it is certainly persuasive
> evidence.)
On Thu, May 12, 2005 at 09:02:05AM +0200, Kenneth Geisshirt wrote:
>
> The Debian Cluster Components (DCC) project uses Torque as batch system.
> IMHO it would be better to include DCC in Debian.
>
Ideally we'd have both PBS/Torque/maui packages and SGE packages to
fullfill both types of scheduling needs, and hopefully get at least one into
Debian/main. SGE's new license (SISSL) is claimed by Sun to be a certified
Open Source License. I've read it and suspect that may be true, but it
would need careful examination on debian-legal (30K in HTML). Alternatives
or conflicts would both be adequate solutions to sharing the names - it
doesn't really make sense to put multiple queueing systems on a compute
node. DQS successfully held off quakestat from taking the qstat name at
least. :)
-Drake
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