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Date: Thu, 11 Dec 2014 12:41:48 +0100
To: "Dmitry Stogov" <dmitry@zend.com>
Cc: "PHP Internals" <internals@lists.php.net>,
 "Xinchen Hui" <xinchen.h@zend.com>,
 "Zeev Suraski" <zeev@zend.com>,
 "Nikita Popov" <nikita.ppv@gmail.com>,
 "Derick" <derick@php.net>,
 "Joe Watkins" <krakjoe@php.net>,
 "Bob Weinand" <bobwei9@hotmail.com>
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Subject: Re: [PHP-DEV] 64-bit performance improvement by reducing zend_op
 size.
From: anatol.php@belski.net ("Anatol Belski")

Hi,

On Wed, December 10, 2014 16:27, Dmitry Stogov wrote:
> Hi,
>
>
> Please, review the following patch
> https://gist.github.com/dstogov/fba2cc621ef121826efe
>
>
> It's huge, but actually, only changes in zend_compile.h are matter. The
> rest is obvious renaming.
>
> the main idea - the smaller the zend_op structure, the lees memory
> traffic is required to load VM instructions during execution. The patch
> reduces the size of each opcode from 48 to 32 bytes (saves 16 bytes for
> each opcode, and applications use thousands of opoceds). This reduced the
> number of CPU cache misses by 12% and improved performance of real-life
> apps by 1-2%.
>
> The patch affects how constants and jump targets are represented in VM
> during execution. Previously they were implemented as absolute 64-bit
> pointers. Now they are relative 32-bit offsets.
>
> In run-time constant now should be accessed as:
> RT_CONSTANT(op_array, opine->op1) instead of opline->op1.zv
> EX_CONSTANT(opline->op1) instead of opline->op1.zv
>
>
> Jump targets:
> OP_JMP_ADDR(opline, opline->op2) instead of opline->op2.jmp_addr
>
>
> The patch doesn't change zend_op representation for 32-bit systems. They
> still use absolute addresses. The compile-time representation is also kept
>  the same.
>
> The patch must affect xdebug and may be other very engine depended
> extensions, but it must not be a big problem to fix them (only
> ext/opcache, ext/reflection and sapi/phpdbg required minor changes).
>
> If nobody objects, I'm going to commit this.
>
>
> Thanks. Dmitry.
>
>
For those willing to test on Windows, a build is available here
http://windows.php.net/downloads/snaps/ostc/zend_op_12/ . Perf tests with
real apps are still outstanding, but from what i've tested so far there
are no regressions.

Regards

anatol