On Tue, Sep 15, 2015 at 4:31 AM, Rasmus Lerdorf <ras...@lerdorf.com> wrote:
> 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. > Yeah. This is transparent solution. At first it's disabled by default by opcache.huge_code_pages=0. At second, it should work without problem if OS doesn't provide huge pages. > > 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. > PHP prefers using regular Huge Pages and may fail back to THP (Transparent Huge Pages). So THP don't have to be enabled. > > 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. > Right. Manual OS configuration is required. See https://wiki.debian.org/Hugepages#Enabling_HugeTlbPage Steps (3) and (4) are optional. Thanks. Dmitry. > > -Rasmus > >
