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Cc: Anatol Belski <anatol.php@belski.net>, Anatol Belski <ab@php.net>,
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Date: Tue, 15 Sep 2015 01:24:22 -0700
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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: rasmus@lerdorf.com (Rasmus Lerdorf)

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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 hugepag=
e
>     tools to make it easy to configure. And from a quick look at Debnia=
n
>     (jessie) it wasn't obvious how to get hugepages working. I don't se=
e a
>     package for hugeadm offhand. The kernel supports it, obviously, but=
 you
>     need to take some steps to configure them.
>=20
>=20
> PHP prefers using regular Huge Pages and may fail back to THP
> (Transparent Huge Pages).
> So THP don't have to be enabled.
> =20
>=20
>=20
>     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.
>=20
>=20
> 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.

-Rasmus


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