From: Will M Farr <farr@MIT.EDU>
To: caml-list@inria.fr
Subject: Re: [Caml-list] Optimizing Float Ref's
Date: Thu, 3 Sep 2009 06:15:10 -0400 [thread overview]
Message-ID: <3FD35494-8478-4F88-9282-6B9F68D608F9@mit.edu> (raw)
In-Reply-To: <4A9F9015.2010408@inria.fr>
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Xavier,
Thanks for the comments. I thought that float ref's were unboxed by
default! In fact, I find that breaking out the code into a stand-
alone example which loops through matrix multiplies only indeed does
not have any calls to "caml_modify"; everything is unboxed and stored
on the stack (I'm on x86) as you say. It must be the remainder of my
application that is producing the calls to caml_modify (the profile I
was using was embedded in a larger application with lots of inlining
going on, so maybe something that calls caml_modify is getting inlined
around the matrix multiply and confusing the profiler).
Thanks,
Will
On Sep 3, 2009, at 5:44 AM, Xavier Leroy wrote:
>> I'm running OCaml 3.11.1, and I noticed something strange in some
>> native code for matrix multiply today. The code was
>> [...]
>> [Local float ref being unboxed or not? ]
>
> You omitted the definition of "dims", but after adding the obvious
> definition, the float ref "sum" is indeed completely unboxed and is
> kept in a float register (on x86-64 bits) or stack location (on x86-32
> bits). No "modify" takes place in the inner loop. So, I don't
> understand the problem you observed. Feel free to post a report on
> the BTS with a *complete* piece of code that reproduces the problem.
>
>> But, I thought that float ref's were automatically unboxed by the
>> compiler when they didn't escape the local context.
>
> Yes, if all uses of the float ref are unboxed, which is the case in
> your code.
>
> - Xavier Leroy
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next prev parent reply other threads:[~2009-09-03 10:15 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-28 20:32 Will M Farr
2009-08-30 19:43 ` [Caml-list] " Yaron Minsky
2009-08-31 14:09 ` Till Varoquaux
2009-08-31 14:51 ` Will M Farr
2009-08-31 17:30 ` Jon Harrop
2009-08-31 17:15 ` Jon Harrop
2009-09-03 9:44 ` Xavier Leroy
2009-09-03 10:15 ` Will M Farr [this message]
2010-03-31 17:21 ` Dmitry Bely
[not found] ` <p2tc7e4e9f1003311055xce0919wac2118aa3c05f1cb@mail.gmail.com>
2010-03-31 18:28 ` Dmitry Bely
2010-03-31 18:59 ` Alain Frisch
2010-03-31 19:18 ` Dmitry Bely
[not found] ` <m2lfbd71dab1003311252v5bda5d13vc2146d2d24270847@mail.gmail.com>
2010-03-31 20:00 ` Dmitry Bely
2010-04-14 18:13 ` Goswin von Brederlow
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