Notes on fdatasync for the test suite

[Roland Mas]

John Arbash Meinel, 2011-08-26 16:06:48 +0200 :

> I've been feeling the pain of how slow our test suite has been lately,
> and I figured I'd poke around a bit if I could.
>
> Basically, our test suite is now running about 3.5hrs per run, where
> back in May it was running 45min per run. I don't have concrete
> evidence of the cause. It seems to be something in 2.4, but it may/may
> not be the fdatasync change. I see some runs before fdatasync landed
> that were 2hrs, though that could be human-submission delay.
>
> I'm planning on looking into this a bit more, since it is actually a
> 4.5x slowdown. And it has started showing up significantly in our
> process.

  You may like to investigate running the testsuite under the eatmydata
wrapper; it's an LD_PRELOAD hack that makes stuff faster by disabling
all kinds of sync-like behaviour.

Roland.
-- 
Roland Mas

That's one of the good fings about not existin'; they leave you alone most
of the time.  --  in My Hero (Tom Holt)