Messages in this thread |  | | Date | Tue, 10 Jul 2001 22:51:03 -0300 (BRT) | From | Marcelo Tosatti <> | Subject | Re: dead mem pages -> dead machines |
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On Tue, 10 Jul 2001, Dirk Wetter wrote:
> > On Tue, 10 Jul 2001, Mark Hahn wrote: > > > > my point, perhaps to terse, was that you shouldn't run 4.3G of job on > > a 4G machine, and expect everything to necessarily work. > > then i expect to have 300M+ swapped out and not 2.6GB. so what? > > > > > they should all have the same priority, so swapping is distributed. > > > > currently sda5 fills (and judging by the 5, it's not on the fast > > > > part of the disk) before sdb1 is used. > > > > > > well, that's the symptom, but not the disease, medically speaking. > > > > no, it's actually orthogonal, mathematically speaking: > > your swap configuration is inefficient > > i am complaining about the fact that the machines start paging > heavily without a reason and you are telling me that my swap > config is wrong? > > > note also that swap listed as in use is really just allocated, > > not necessarily used. the current VM preemptively assigns idle pages > > to swapcache; whether they ever get written out is another matter. > > it IS used. after submitting the jobs the nodes were dead for a while since > they were swapping like hell. > > > you should clearly run "vmstat 1" to see whether there's significant > > si/so. it would be a symptom if there was actually a lot of *both* > > si and so (thrashing). > > they were so dead, i couldn't even type on the console. load was up > to 30, culprit at that point was kswapd.
Dirk,
Can you boot the kernel with "profile=2" and use the "readprofile" tool to check where the kernel is wasting its time ? (take a look at the readprofile man page)
Let me machine stay in the "unusable" state for quite some time before reading the statistics.
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