On Jul 2, 2009, at 5:34 AM, Marc Lehmann wrote:
On Wed, Jul 01, 2009 at 09:39:19PM -0400, Andy Grundman <[email protected]
> wrote:
Two problems with this patch:
Actually, looking at it, it patches against the higher-resolution
clock
alraedy in use in CVS. on the w2000, xp and vista amchiens I tested,
the resolution is much higher than 1ms - are you sure it only has 1ms
resolution? In that case it might be worthwhile to investigate why
your
machine has such a low resolution when the reslution approaches more
like
25µs over such a wide variatey of windows versions normally.
OK, before you dismiss it, here's the original problem I was trying to
solve. I was using Perl EV 3.6 which didn't have the latest CVS fix
in it, and saw that the resolution was only 3 decimal places. This
causes some issues when trying to use EV::time instead of
Time::HiRes::time for measuring execution time, for example. I tried
out the CVS version which improves this to 5 decimal places, but does
not increase the value every time it's called, as happens with T::H.
(libev would only increase the value every 1ms.) That's the main
issue I was trying to fix. It's a very ugly hack but I'm not sure
there is any other way of achieving the desired resolution. :(
The method you propose is totally unworkable on multicore machines,
and
requires special hardware to begin with. It cannot be used inside a
portable library (if you google for a while, you will see that this
emthod
is often implemented for a while in other libraries, and then removed,
because it doesn't work in practise).
It seems to work fine on my quad-core Windows box in a single-threaded
program, but yeah I see the potential issues.
Also note that libev doesn't guarantee any higher precision then
around
1ms even on systems supporting higher resolutions.
Really? I thought Linux/Mac would be fine in this respect.
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