Messages in this thread | | | Date | Wed, 22 Mar 2000 07:33:12 -0600 (CST) | From | Jesse Pollard <> | Subject | Re: Avoiding OOM on overcommit...? |
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James Sutherland <jas88@cam.ac.uk> > On Tue, 21 Mar 2000 11:43:02 -0600 (CST), you wrote: > >David Whysong <dwhysong@physics.ucsb.edu>: > >> On Mon, 20 Mar 2000, Jesse Pollard wrote: > >> >On Mon, 20 Mar 2000, David Whysong wrote: > >> >> > >> >>That's very misleading. In fact if you give the overcommitted system the > >> >>same amount of VM, it will work just fine. In other words, turning off > >> >>overcommit isn't what saves you. You added more memory! > >> > > >> >I guaranteed that the memory allocated could be used. I didn't just add > >> >more memory. Just adding more memory will still allow the system to fail, > >> >it may take longer, it may not happen as often. But it can still happen. > >> > >> If you properly handle system-wide OOM situations by killing tasks (see my > >> other emails about doing this with the OOM killer patch + a userspace > >> daemon), then you no longer have system crashes. > >> > >> Yes, your app can be killed, but that is also what happens with quotas. In > >> fact, it happens earlier with quotas. > > > >It happens before the OOM can kill the system. It happens before my process > >causes other users to loose theirs. > > The shortage of memory cannot kill the system. It can just kill > processes. A kernel bug can kill the system, but that's another issue. > > >You obviously haven't used a large multiuser system recently. Quotas are > >applied in almost every location I've seen. Why - to prevent one users > >job from interfereing with other users jobs. > > Quotas are essential, and I still can't see why Linux lacks them... > > >If you were running a simulation/analysis and were supposedly given > >resources to run, and I accessed the same system with the same goal in > >mind, which user gets killed when I use up the resources given to me? ^^^^^^^^^^^ > >BTW, I have the same priority of access to the system that you have... > > Yours, if you don't have enough resources available to you to run it. > Otherwise, both run fine.
BUT "when I use up the resources given to me" - If the resources weren't available, why did the system give them to me?
> >Who gets killed - your process or mine? > Yours, because there aren't enough resources to run it.
The system told me there were enough resources.
> >Which is the correct one? > Yours, as above.
As determined by what?
> >How do you know it is the correct one? > Because it would put you above the limit available to you.
But the system told me the resources were available. And what limit? The kernel doesn't support resource quotas.
> >If it happens again, are the answers the same? > Yes.
BUGGGY. The system gave the resource to me. See above. What distinguishes my job from yours? ------------------------------------------------------------------------- Jesse I Pollard, II Email: pollard@navo.hpc.mil
Any opinions expressed are solely my own.
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