Doc #38678 [Asn->Csd]: APC docs need mmap infos

Edit report at http://bugs.php.net/bug.php?id=38678&edit=1 ID: 38678 Updated by: kalle@php.net Reported by: thomas-lists at mysnip dot de Summary: APC docs need mmap infos -Status: Assigned +Status: Closed Type: Documentation Problem Package: Documentation problem Operating System: Linux PHP Version: Irrelevant -Assigned To: gopalv +Assigned To: kalle Block user comment: N New Comment: This bug has been fixed in the documentation's XML sources. Since the online and downloadable versions of the documentation need some time to get updated, we would like to ask you to be a bit patient. Thank you for the report, and for helping us make our documentation better. Previous Comments: ------------------------------------------------------------------------ [2010-10-24 16:29:44] kalle@php.net Automatic comment from SVN on behalf of kalle Revision: http://svn.php.net/viewvc/?view=revision&revision=304704 Log: Fixed bug #38678 (APC docs need mmap infos) with notes from Gopal ------------------------------------------------------------------------ [2010-10-23 17:52:22] gopalv@php.net The shmmax limit is the reason there was a need for multiple segments in the first place. phpinfo() does mention that MMAP Support is enabled & the locking type used for an install. mmap() is a nicer and easier way to overcommit memory (i.e the OS will only use physical pages once you read/write a block) reducing the impact of memory allocation at startup. Also mmap() in that fashion ensures that the system reclaims memory quickly and easily when apache is shut down & restarted. It also lends itself to some nice tricks http://notmysock.org/blog/hacks/memory-rowr Shm mode is kept around just for one reason. It's the SysV standard to do this kind of thing. ------------------------------------------------------------------------ [2010-01-17 15:45:14] bjori@php.net Gopal: could you help us out here? ------------------------------------------------------------------------ [2006-09-01 09:49:38] thomas-lists at mysnip dot de Description: ------------ coming from http://news.php.net/php.pecl.dev/4095 pointed here from http://news.php.net/php.pecl.dev/4096 The APC docs don't tell anything about how memory is used in mmap mode. e.g. that - maximum shm-segment-size told in /proc/sys/kernel/shmmax isn't in effect here - mmap uses only one segment and currently uses only the size specified in apc-config for the shm-segments (see bug http://pecl.php.net/bugs/bug.php?id=8609 , maybe that changes) - currently one can only guess which mode is used but I think the phpinfo tells at least "mmap is enabled" ( see bug http://pecl.php.net/bugs/bug.php?id=8608 at pecl.php.net) As mmap-mode is the default nowadays in apc it would be good to tell some more about its configuration :). If one could add the pros/cons of using mmap over shm it would be great too! ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/bug.php?id=38678&edit=1