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Date: Thu, 11 Dec 2014 14:42:42 +0800
Message-ID: <CABBJUpc+3BrZ+i+QnHCHahjt3iK7TA4FM4zYzepTWQbAUbOtZA@mail.gmail.com>
To: Dmitry Stogov <dmitry@zend.com>
Cc: PHP Internals <internals@lists.php.net>, 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: text/plain; charset=UTF-8
Subject: Re: 64-bit performance improvement by reducing zend_op size.
From: xinchen.h@zend.com (Xinchen Hui)

Hey:

On Wed, Dec 10, 2014 at 11:27 PM, 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.
As I already participated in this patch, I have no problems & objections.

thanks

>
> Thanks. Dmitry.
>



-- 
Xinchen Hui
@Laruence
http://www.laruence.com/