"how do I see how much of the pagepool is in use and by what? I've looked at mmfsadm dump and mmdiag --memory and neither has provided me the information I'm looking for (or at least not in a format I understand)"
+1. Pointers appreciated! :-) On 10 April 2018 at 17:22, Aaron Knister <[email protected]> wrote: > I wonder if this is an artifact of pagepool exhaustion which makes me ask > the question-- how do I see how much of the pagepool is in use and by what? > I've looked at mmfsadm dump and mmdiag --memory and neither has provided me > the information I'm looking for (or at least not in a format I understand). > > -Aaron > > On 4/10/18 12:00 PM, Knister, Aaron S. (GSFC-606.2)[COMPUTER SCIENCE CORP] > wrote: > >> I hate admitting this but I’ve found something that’s got me stumped. >> >> We have a user running an MPI job on the system. Each rank opens up >> several output files to which it writes ASCII debug information. The net >> result across several hundred ranks is an absolute smattering of teeny tiny >> I/o requests to te underlying disks which they don’t appreciate. >> Performance plummets. The I/o requests are 30 to 80 bytes in size. What I >> don’t understand is why these write requests aren’t getting batched up into >> larger write requests to the underlying disks. >> >> If I do something like “df if=/dev/zero of=foo bs=8k” on a node I see >> that the nasty unaligned 8k io requests are batched up into nice 1M I/o >> requests before they hit the NSD. >> >> As best I can tell the application isn’t doing any fsync’s and isn’t >> doing direct io to these files. >> >> Can anyone explain why seemingly very similar io workloads appear to >> result in well formed NSD I/O in one case and awful I/o in another? >> >> Thanks! >> >> -Stumped >> >> >> >> >> _______________________________________________ >> gpfsug-discuss mailing list >> gpfsug-discuss at spectrumscale.org >> http://gpfsug.org/mailman/listinfo/gpfsug-discuss >> >> > -- > Aaron Knister > NASA Center for Climate Simulation (Code 606.2) > Goddard Space Flight Center > (301) 286-2776 > _______________________________________________ > gpfsug-discuss mailing list > gpfsug-discuss at spectrumscale.org > http://gpfsug.org/mailman/listinfo/gpfsug-discuss > -- [image: Framestore] Peter Smith · Senior Systems Engineer London · New York · Los Angeles · Chicago · Montréal T +44 (0)20 7208 2600 · M +44 (0)7816 123009 <+44%20%280%297816%20123009> 28 Chancery Lane, London WC2A 1LB <https://www.google.co.uk/maps/place/19-23+Wells+Street,+London+W1T+3PQ> Twitter <https://twitter.com/framestore> · Facebook <https://www.facebook.com/framestore> · framestore.com <http://www.framestore.com>
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