On 09/14/2015 02:13 PM, Anatol Belski wrote: > > >> -----Original Message----- >> From: Dmitry Stogov [mailto:dmi...@zend.com] >> Sent: Monday, September 14, 2015 10:37 PM >> To: Anatol Belski <anatol....@belski.net> >> Cc: Anatol Belski <a...@php.net>; Kalle Sommer Nielsen <ka...@php.net>; >> Rasmus Lerdorf <ras...@lerdorf.com>; Xinchen Hui <xinche...@zend.com>; >> Nikita Popov <nikita....@gmail.com>; Zeev Suraski <z...@zend.com>; Andi >> Gutmans <a...@zend.com>; PHP Internals <internals@lists.php.net> >> Subject: Re: [PHP-DEV] Re: [PHP-CVS] com php-src: Added an experemental >> ability to move PHP code pages (PHP TEXT segment) into HUGE pages. PHP >> should be configured and built with --enable-huge-code-pages, OS should be >> configured to provide huge pages. It's possibl >> >>> >>> With the new huge memory pages feature I'd suggest a bit softer - >>> enabling its building, but setting opcache.enable_huge_code_pages=0 by >> default. >> >> >> OK. >> >> >>> Then it can be easy enable and give one more intermediate step for pre >>> testing and go into RC4 completely if ok. >> >> >> In general we may get build problems on some platforms... >> >> >>> What do you think? >>> >> >> I didn't get, do you like to delay this for RC4? or enable it at compile >> time and >> disable at run-time by default for RC3? >> I agree with both. >> > I was suggesting the latter - build and disable at run-time. With RC4 I meant > - as it's run-time enabled by default currently, that could be turned on by > default in RC4 if everything was well in RC3. > > Regarding possible build issues you mention - probably some magic in > config.m4 could disable huge pages? I wasn't aware, but probably yep - like > FreeBSD or OSX likely to not to have the sys/prctl.h . This could be a reason > for delaying till RC4, but it's actually easy solved doing some test > compilation in config.m4 . I'd see build + disable on run-time in RC3 as a > better move because it turns the test circle earlier which is good > considering there are only 4 RCs to go yet.
As long as we fail gracefully when compiled with hugepage support and then run on a system that doesn't have any hugepages configured. These days the build box and the production execution box are rarely the same machine. Redhat enables THP by default and has for a while, but I know lots of admins that disable this feature right away on production machines. I don't think it is default on Ubuntu, but at least they have hugepage tools to make it easy to configure. And from a quick look at Debnian (jessie) it wasn't obvious how to get hugepages working. I don't see a package for hugeadm offhand. The kernel supports it, obviously, but you need to take some steps to configure them. Which means we also need to spend a bit of time documenting how to enable hugepages at the OS level for the various operating systems to go along with this feature. -Rasmus
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