On 2/14/19 8:55 PM, Anatol Belski wrote: > Hi Nikita, > >> -----Original Message----- >> From: Nikita Popov <nikita....@gmail.com> >> Sent: Wednesday, February 13, 2019 1:02 AM >> To: Dmitry Stogov <dmi...@zend.com> >> Cc: Joe Watkins <krak...@gmail.com>; Bob Weinand <bwo...@php.net>; >> Nikita Popov <ni...@php.net>; Anatol Belski (a...@php.net) <a...@php.net>; >> z...@php.net; PHP internals <internals@lists.php.net> >> Subject: Re: ZTS improvement idea >> >> On Wed, Feb 13, 2019 at 9:26 AM Dmitry Stogov <dmi...@zend.com >> <mailto:dmi...@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. >> > TLS data available across shared objects is a GNU extension and AFAIK there's > a lot of black magic behind it. Thread local storage should be indeed local > to some scope, be it a function or a binary unit, as per design. Like for > C++11 as well, it's thread_local we currently use. It'd hurt the portability > and likely introduce issues in the future, as it might affect any non GNU > systems which we rarely test. Otherwise, of course it would be easy to say, > we add ZEND_TLS to the definition, and be good :)
In two words, if we make executor_glabal to be "__thread", we will get troubles accessing it from DSO extensions. Right? Thanks. Dmitry. > > Thanks > > Anatol >
