Hi Arnaud, I remember that at the time we looked at thread local storage and there were some real issues with it. I can't remember what as it was about 7+ years ago. I will ask Zeev if he remembers and if not search my archives (don't have years prior to 2007 indexed :'( ).
Andi > -----Original Message----- > From: Arnaud Le Blanc [mailto:[EMAIL PROTECTED] > Sent: Saturday, August 16, 2008 7:19 PM > To: PHP Development > Subject: [PHP-DEV] [PATCH] ZTS as fast as non-ZTS > > Hi, > > Currently the way globals work forces to pass a thread-local-storage pointer > across function calls, which involves some overhead. Also, not all functions > get the pointer as argument and need to use TSRMLS_FETCH(), which is slow. For > instance emalloc() involves a TSRMLS_FETCH(). An other overhead is accessing > globals, using multiple pointers in different locations. > > The following patch caches each global address in a native TLS variable so > that accessing a global is as simple as global_name->member. This removes the > requirement of passing the tls pointer across function calls, so that the two > major overheads of ZTS builds are avoided. > > Globals can optionally be declared statically, which speeds up things a bit. > > Results in bench.php: > non-ZTS: 3.7s > ZTS unpatched: 5.2s > ZTS patched: 4.0s > ZTS patched and static globals: 3.8s > > The patch introduces two new macros: TSRMG_D() (declare) and TSRMG_DH() > (declare, for headers) to declare globals, instead of the current "ts_rsrc_id > foo_global_id". These macros declare the global id, plus the __thread pointer > to the global storage. > > ts_allocate_id now takes one more callback function as argument to bind the > global pointer to its storage. This callback is declared in TSRMG_D[H](). > > As all TSRMLS_* macros now does nothing, it is needed to call ts_resource(0) > explicitly at least one time in each thread to initialize its storage. A new > TSRMLS_INIT() macro as been added for this purpose. > > All this is disabled by default. --with-tsrm-__thread-tls enables the features > of the patch, and --with-tsrm-full-__thread-tls enables static declaration of > globals. > > It as been tested on Linux compiled with --disable-all in CLI and a bit in > Apache2 with the worker MPM. Known issues: > - Declaring globals statically (--with-tsrm-full-__thread-tls) causes troubles > to dlopen(), actually Apache wont load the module at runtime (it works with > just --with-tsrm-__thread-tls). > - The patch assumes that all resources are ts_allocate_id()'ed before any > other thread calls ts_allocate_id or ts_resource_ex(), which is possibly not > the case. > > The patch needs some tweaks and does not pretend to be included in any branch, > but I would like to have some comments on it. > > The patch: http://arnaud.lb.s3.amazonaws.com/__thread-tls.patch > > Regards, > > Arnaud > > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: http://www.php.net/unsub.php -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
