Re: pg_test_fsync performance

On Wed, Feb 15, 2012 at 16:14, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> On Wed, Feb 15, 2012 at 09:54:04AM +0100, Magnus Hagander wrote:
>> On Wed, Feb 15, 2012 at 02:23, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>> > On Wed, Feb 15, 2012 at 01:35:05AM +0200, Marko Kreen wrote:
>> >> On Tue, Feb 14, 2012 at 05:59:06PM -0500, Tom Lane wrote:
>> >> > Bruce Momjian <bruce(at)momjian(dot)us> writes:
>> >> > > On Mon, Feb 13, 2012 at 08:28:03PM -0500, Tom Lane wrote:
>> >> > >> +1, I was about to suggest the same thing.  Running any of these tests
>> >> > >> for a fixed number of iterations will result in drastic degradation of
>> >> > >> accuracy as soon as the machine's behavior changes noticeably from what
>> >> > >> you were expecting.  Run them for a fixed time period instead.  Or maybe
>> >> > >> do a few, then check elapsed time and estimate a number of iterations to
>> >> > >> use, if you're worried about the cost of doing gettimeofday after each
>> >> > >> write.
>> >> >
>> >> > > Good idea, and it worked out very well.  I changed the -o loops
>> >> > > parameter to -s seconds which calls alarm() after (default) 2 seconds,
>> >> > > and then once the operation completes, computes a duration per
>> >> > > operation.
>> >> >
>> >> > I was kind of wondering how portable alarm() is, and the answer
>> >> > according to the buildfarm is that it isn't.
>> >>
>> >> I'm using following simplistic alarm() implementation for win32:
>> >>
>> >>   https://github.com/markokr/libusual/blob/master/usual/signal.c#L21
>> >>
>> >> this works with fake sigaction()/SIGALARM hack below - to remember
>> >> function to call.
>> >>
>> >> Good enough for simple stats printing, and avoids win32-specific
>> >> code spreading around.
>> >
>> > Wow, I wasn't even aware this compiled in Win32;  I thought it was
>> > ifdef'ed out.  Anyway, I am looking at SetTimer as a way of making this
>> > work.  (Me wonders if the GoGrid Windows images have compilers.)
>>
>> They don't, since most of the compilers people would ask for don't
>> allow that kind of redistribution.
>
> Shame.
>
>> Ping me on im if you need one preconfigured, though...
>
> How do you do that?  Also, once you create a Windows VM on a public
> cloud, how do you connect to it?  SSH?

rdesktop.

--
 Magnus Hagander
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