On Wed, 21 Jun 2006, Zeev Suraski wrote:
> Well, as I said I think it actually makes the code more readable, by hinting
> you what you can ignore if you're running through the 'common case' (i.e.,
> even if this macro was a no-op). Diving into a big block of code is easier if
> you can ignore par
: Zeev Suraski [mailto:[EMAIL PROTECTED]
>Sent: Tuesday, June 20, 2006 7:17 AM
>To: Andi Gutmans
>Cc: 'Nuno Lopes'; 'PHPdev'
>Subject: RE: [PHP-DEV] messing with branch prediction
>
>I still don't see how it can hurt, and even if it doesn't do
>
Comments bellow:
>-Original Message-
>
>First, let me thank you all that reviewed the patch.
>When I first sent the patch to the list I didn't meant I
>wanted it to be integrated with the main php sources. At least
>before running some benchmarks and double-checking it. That
>patch was
2006 7:17 AM
>To: Andi Gutmans
>Cc: 'Nuno Lopes'; 'PHPdev'
>Subject: RE: [PHP-DEV] messing with branch prediction
>
>I still don't see how it can hurt, and even if it doesn't do
>anything performance wise, it adds clarity to the code.
>
>Zeev
>
I think it's a nice idea but I doubt it's very useful at this point. It
doesn't seem to significantly affect performance, which is inline with
some
tests that we have done in the past, where it's really the hardware
management of branch prediction and cache size which affect this. I doubt
that m
IL PROTECTED]
>Sent: Monday, June 19, 2006 12:46 AM
>To: Nuno Lopes
>Cc: PHPdev
>Subject: Re: [PHP-DEV] messing with branch prediction
>
>Definitely looks nice. I actually like how it makes the code
>more readable hinting which branches are rare.
>
>Zeev
>
>At 16:4
> Instead of guessing branch probabilities, why not measure them?
Or, simply tell the compiler what you expect. Sometimes, GCC
predicts incorrectly - if-branches are usually assumed _not_
to be executed.
if (expect_true(x)) {
foo();
}
with..
#ifdef HAVE_BUILTIN_
> Andi Gutmans wrote:
> I think it's a nice idea but I doubt it's very useful at this point. It
> doesn't seem to significantly affect performance, which is ...
I concur.
Instead of guessing branch probabilities, why not measure them?
http://gcc.gnu.org/onlinedocs/gcc-4.1.1/gcc/Optimize-Options
ms that
the hardware is playing pretty nice with us.
>-Original Message-
>From: Zeev Suraski [mailto:[EMAIL PROTECTED]
>Sent: Monday, June 19, 2006 12:46 AM
>To: Nuno Lopes
>Cc: PHPdev
>Subject: Re: [PHP-DEV] messing with branch prediction
>
>Definitely looks
Definitely looks nice. I actually like how it makes the code more
readable hinting which branches are rare.
Zeev
At 16:49 18/06/2006, Nuno Lopes wrote:
Hello,
Yesterday I was playing with branch prediction in the Zend VM
executor. Although I didn't have any noticeable performance
improveme
Looks like an interesting patch, if it does not cost us any
performance and only offers either no gain or a small gain I'd say it
would be worth inclusion. Perhaps branch prediction will work better
with newer versions of gcc like 4.0 or 4.1
On 18-Jun-06, at 9:49 AM, Nuno Lopes wrote:
He
Hello,
Yesterday I was playing with branch prediction in the Zend VM executor.
Although I didn't have any noticeable performance improvement within the
bench.php script, I've put the patch on-line, because someone else might
want to mess with it too :) (but with care..)
patch: http://mega.is
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