MicroSD Card performance variance on XO-1.5

Bernie Innocenti bernie at codewiz.org
Fri Aug 6 20:52:54 EDT 2010

El Fri, 06-08-2010 a las 18:50 +0200, Tomeu Vizoso escribió:
> > I also think our vm.dirty_* settings are wrong and likely causing our
> > current fill-buffer-and-stutter behaviour. We are using the defaults
> > and those are for spinning harddrives, with a significant cost to
> > spinning up the disk on a laptop -- hence long expire_centisecs and
> > writeback_centisecs and the assumption that once you've started
> > writing, it'll be written out fast. We have zero seek costs, zero
> > "spin disk up" costs, but slowish writes -- we have to start writing
> > buffers out ASAP.
> I had also had the impression for some time that some knobs in the
> kernel could have been better tuned for the XO-1 and the actual
> workload.

That was also my gut feeling.

Swappiness also seems to be set too high. We should probably let the OOM
killer kick in before the machine becomes totally unresponsive.

Tuning the VM knobs is no joke. We could proceed by applying some
reasonable changes early in the next development cycle, then sit back
and wait for users to tell us their overall impression of using the
system as usual.

   // Bernie Innocenti - http://codewiz.org/
 \X/  Sugar Labs       - http://sugarlabs.org/

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