[gpfsug-discuss] iowait?
Aaron Knister
aaron.s.knister at nasa.gov
Mon Aug 29 18:33:59 BST 2016
Hi Everyone,
Would it be easy to have GPFS report iowait values in linux? This would
be a huge help for us in determining whether a node's low utilization is
due to some issue with the code running on it or if it's blocked on I/O,
especially in a historical context.
I naively tried on a test system changing schedule() in
cxiWaitEventWait() on line ~2832 in gpl-linux/cxiSystem.c to this:
again:
/* call the scheduler */
if ( waitFlags & INTERRUPTIBLE )
schedule();
else
io_schedule();
Seems to actually do what I'm after but generally bad things happen when
I start pretending I'm a kernel developer.
Any thoughts? If I open an RFE would this be something that's relatively
easy to implement (not asking for a commitment *to* implement it, just
that I'm not asking for something seemingly simple that's actually
fairly hard to implement)?
-Aaron
--
Aaron Knister
NASA Center for Climate Simulation (Code 606.2)
Goddard Space Flight Center
(301) 286-2776
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