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Date: Tue, 15 Sep 2015 12:49:55 +0300
Message-ID: <CA+9eiLvtBA2XBZrWH8wsoxr1vjSJ_w-CjaoMsCBNNrQGyp4kEg@mail.gmail.com>
To: Rasmus Lerdorf <rasmus@lerdorf.com>
Cc: Anatol Belski <anatol.php@belski.net>, Anatol Belski <ab@php.net>, 
	Kalle Sommer Nielsen <kalle@php.net>, Xinchen Hui <xinchen.h@zend.com>, Nikita Popov <nikita.ppv@gmail.com>, 
	Zeev Suraski <zeev@zend.com>, Andi Gutmans <andi@zend.com>, PHP Internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a11415a8eb51c1a051fc61a96
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
From: dmitry@zend.com (Dmitry Stogov)

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On Tue, Sep 15, 2015 at 11:24 AM, Rasmus Lerdorf <rasmus@lerdorf.com> wrote:

> On 09/14/2015 11:58 PM, Dmitry Stogov wrote:
> > On Tue, Sep 15, 2015 at 4:31 AM, Rasmus Lerdorf <rasmus@lerdorf.com
> > <mailto:rasmus@lerdorf.com>> wrote:
> >     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.
>
> Yup. I did get it working here. Perhaps it would be a good idea to add a
> row to the phpinfo() OpCache section indicating whether huge pages are
> currently being used. It would make it easier to debug. I know you can
> check /proc/meminfo directly, but it isn't obvious what exactly is using
> the hugepages from that.
>

It's possible to get detailed information form /proc/<pid>/smaps
Actually, PHP may use huge pages for Zend MM, opcache SHM and now for a
part of PHP code segment.

Thanks. Dmitry.


>
> -Rasmus
>
>

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