Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:104379
MIME-Version: 1.0
References: <BYAPR02MB5766B8D8FCE674BF544B7FB0BF660@BYAPR02MB5766.namprd02.prod.outlook.com>
In-Reply-To: <BYAPR02MB5766B8D8FCE674BF544B7FB0BF660@BYAPR02MB5766.namprd02.prod.outlook.com>
Date: Wed, 13 Feb 2019 10:02:16 +0100
Message-ID: <CAF+90c9uK1+xW1HbUq5BeiWxxP6bNb6CiVS6AXMoBNo1OMPKVw@mail.gmail.com>
To: Dmitry Stogov <dmitry@zend.com>
Cc: Joe Watkins <krakjoe@gmail.com>, Bob Weinand <bwoebi@php.net>, Nikita Popov <nikic@php.net>, 
	"Anatol Belski (ab@php.net)" <ab@php.net>, "zeev@php.net" <zeev@php.net>, PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="00000000000059a79b0581c2cda1"
Subject: Re: ZTS improvement idea
From: nikita.ppv@gmail.com (Nikita Popov)

--00000000000059a79b0581c2cda1
Content-Type: text/plain; charset="UTF-8"

On Wed, Feb 13, 2019 at 9:26 AM Dmitry Stogov <dmitry@zend.com> wrote:

> Hi,
>
>
> After JIT+ZTS related discussion with Joe and Bob, and some related
> analyzes.
>
> I came to more or less formed design idea and described it at
> https://wiki.php.net/zts-improvement
>
> This is not an RFC and I'm not sure, if I like to implement TSRM changes
> myself now.
>
>
> Comments are welcome.
>

Hi Dmitry,

Thanks for looking into this issue. As a possible alternative I would like
to suggest the use of ZEND_TLS (__thread) for the EG/CG/BG etc globals on
Linux (on Windows this is not possible due to DLL linkage restrictions).
__thread generates very good code (single load over %fs segment with
constant address) if the global is defined and used in an executable. I'm
not sure what kind of code it generates when TLS is declared in an
executable and used in a shared object, but as direct access from
extensions to the engine globals shouldn't be common, it's probably okay
even if it uses __tls_get_addr.

Nikita

--00000000000059a79b0581c2cda1--