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Date: Wed, 10 Dec 2014 14:34:52 -0500
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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>
Content-Type: multipart/alternative; boundary=047d7b2e0d851fe2300509e1c2d7
Subject: Re: [PHP-DEV] 64-bit performance improvement by reducing zend_op size.
From: guilhermeblanco@gmail.com ("guilhermeblanco@gmail.com")

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Seems good for me. =)

On Wed, Dec 10, 2014 at 10:27 AM, Dmitry Stogov <dmitry@zend.com> 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.
>



-- 
Guilherme Blanco
MSN: guilhermeblanco@hotmail.com
GTalk: guilhermeblanco
Toronto - ON/Canada

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