I tested the same code on my second machine - Debian Squeeze (kernel 2.6.32)
with GHC 7.4.1 - and
the results are extremely surprising. At first I was unable to reproduce the
problem and got
consistent runtimes of about 107us:
benchmarking FFI/C binding
mean: 107.3837 us, lb 107.2013 us, ub
I once had a problem like this. It turned out that my laptop was stepping
the cpu clock rate down whenever it got warm. Disabling that feature in my
BIOS fixed it. Your problem might be similar.
On Nov 27, 2012 7:23 AM, Janek S. fremenz...@poczta.onet.pl wrote:
I tested the same code on my
Dnia wtorek, 27 listopada 2012, Jake McArthur napisał:
I once had a problem like this. It turned out that my laptop was stepping
the cpu clock rate down whenever it got warm. Disabling that feature in my
BIOS fixed it. Your problem might be similar.
I just check - I disabled frequency scaling
Did you pass the option to criterion asking it to do a GC between
trials? You might be measuring a GC pause.
On Tue, Nov 27, 2012 at 2:41 PM, Janek S. fremenz...@poczta.onet.pl wrote:
Dnia wtorek, 27 listopada 2012, Jake McArthur napisał:
I once had a problem like this. It turned out that my
Dnia wtorek, 27 listopada 2012, Gregory Collins napisał:
Did you pass the option to criterion asking it to do a GC between
trials?
Yes.
You might be measuring a GC pause.
On Tue, Nov 27, 2012 at 2:41 PM, Janek S. fremenz...@poczta.onet.pl wrote:
Dnia wtorek, 27 listopada 2012, Jake
Well, it seems that this only happens on my machine. I will try to test this
code on different
computer and see if I can reproduce it.
I don't think using existing vector is a good idea - it would make the code
impure.
Janek
Dnia sobota, 24 listopada 2012, Branimir Maksimovic napisał:
I
I'm using GHC 7.4.2 on x86_64 openSUSE Linux, kernel 2.6.37.6.
Janek
Dnia piątek, 23 listopada 2012, Edward Z. Yang napisał:
Running the sample code on GHC 7.4.2, I don't see the one
fast, rest slow behavior. What version of GHC are you running?
Edward
Excerpts from Janek S.'s message of
I don't see such behavior neither.ubuntu 12.10, ghc 7.4.2.
Perhaps this has to do with how malloc allocates /cachebehavior. If you try not
to allocate array rather use existing one perhaps there would be no
inconsistency?It looks to me that's about CPU cache performance.
Branimir
I'm using
I am using Criterion library to benchmark C code called via FFI bindings and
I've ran into a
problem that looks like a bug.
The first benchmark that uses FFI runs correctly, but subsequent benchmarks run
much longer. I
created demo code (about 50 lines, available at github:
Hello Janek,
What happens if you do the benchmark without unsafePerformIO involved?
Edward
Excerpts from Janek S.'s message of Fri Nov 23 10:44:15 -0500 2012:
I am using Criterion library to benchmark C code called via FFI bindings and
I've ran into a
problem that looks like a bug.
The
What happens if you do the benchmark without unsafePerformIO involved?
I removed unsafePerformIO, changed copy to have type Vector Double - IO
(Vector Double) and
modified benchmarks like this:
bench C binding $ whnfIO (copy signal)
I see no difference - one benchmark runs fast, remaining
Running the sample code on GHC 7.4.2, I don't see the one
fast, rest slow behavior. What version of GHC are you running?
Edward
Excerpts from Janek S.'s message of Fri Nov 23 13:42:03 -0500 2012:
What happens if you do the benchmark without unsafePerformIO involved?
I removed
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