All of lore.kernel.org
 help / color / mirror / Atom feed
From: Zhouping Liu <zliu@redhat.com>
To: Lin Feng <linfeng@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Hugh Dickins <hughd@google.com>, Mel Gorman <mgorman@suse.de>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Amos Kong <akong@redhat.com>
Subject: Re: THP: AnonHugePages in /proc/[pid]/smaps is correct or not?
Date: Tue, 02 Apr 2013 11:48:22 +0800	[thread overview]
Message-ID: <515A5506.1000809@redhat.com> (raw)
In-Reply-To: <515A5329.6020805@cn.fujitsu.com>

On 04/02/2013 11:40 AM, Lin Feng wrote:
> Hi Zhouping,
>
> On 04/02/2013 11:09 AM, Zhouping Liu wrote:
>> I don't understand clearly the last sentence 'you'll probably only get 100% hugepages only 1/512th of the time.'
>> could you please explain more details about 'only 1/512th of the time'?
> IIUC, thp size is 2M so it may be comprised of 512 normal page(size 4k).
> Since your test code is not 2M aligned(not using  posix_memalign()) so
> the start address of the mapped vma will be random, such as
> 2M*i+4k*1, 2M*i+4k*2...2M*i+k4*511, there is 512 possibilities.
>
> The only chance you get thp happens when the first map just starts at 2M*i,
> and the consequent maps also benefit from this.

Feng, it's easy to understand now, thanks for your detailed explanation :)

Zhouping

WARNING: multiple messages have this Message-ID (diff)
From: Zhouping Liu <zliu@redhat.com>
To: Lin Feng <linfeng@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Hugh Dickins <hughd@google.com>, Mel Gorman <mgorman@suse.de>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Amos Kong <akong@redhat.com>
Subject: Re: THP: AnonHugePages in /proc/[pid]/smaps is correct or not?
Date: Tue, 02 Apr 2013 11:48:22 +0800	[thread overview]
Message-ID: <515A5506.1000809@redhat.com> (raw)
In-Reply-To: <515A5329.6020805@cn.fujitsu.com>

On 04/02/2013 11:40 AM, Lin Feng wrote:
> Hi Zhouping,
>
> On 04/02/2013 11:09 AM, Zhouping Liu wrote:
>> I don't understand clearly the last sentence 'you'll probably only get 100% hugepages only 1/512th of the time.'
>> could you please explain more details about 'only 1/512th of the time'?
> IIUC, thp size is 2M so it may be comprised of 512 normal page(size 4k).
> Since your test code is not 2M aligned(not using  posix_memalign()) so
> the start address of the mapped vma will be random, such as
> 2M*i+4k*1, 2M*i+4k*2...2M*i+k4*511, there is 512 possibilities.
>
> The only chance you get thp happens when the first map just starts at 2M*i,
> and the consequent maps also benefit from this.

Feng, it's easy to understand now, thanks for your detailed explanation :)

Zhouping

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

  parent reply	other threads:[~2013-04-02  3:51 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1207916095.642011.1364800448075.JavaMail.root@redhat.com>
2013-04-01  8:00 ` THP: AnonHugePages in /proc/[pid]/smaps is correct or not? Zhouping Liu
2013-04-01  8:00   ` Zhouping Liu
2013-04-01 22:23   ` David Rientjes
2013-04-01 22:23     ` David Rientjes
2013-04-02  3:09     ` Zhouping Liu
2013-04-02  3:09       ` Zhouping Liu
2013-04-02  3:40       ` Lin Feng
2013-04-02  3:40         ` Lin Feng
2013-04-02  3:44         ` David Rientjes
2013-04-02  3:44           ` David Rientjes
2013-04-02  3:48         ` Zhouping Liu [this message]
2013-04-02  3:48           ` Zhouping Liu
2013-04-02 12:23     ` Simon Jeons
2013-04-02 12:23       ` Simon Jeons
2013-04-02 18:09       ` David Rientjes
2013-04-02 18:09         ` David Rientjes
2013-04-02 23:58         ` Simon Jeons
2013-04-02 23:58           ` Simon Jeons
2013-04-02 12:26     ` Simon Jeons
2013-04-02 12:26       ` Simon Jeons

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=515A5506.1000809@redhat.com \
    --to=zliu@redhat.com \
    --cc=aarcange@redhat.com \
    --cc=akong@redhat.com \
    --cc=hughd@google.com \
    --cc=linfeng@cn.fujitsu.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mgorman@suse.de \
    --cc=rientjes@google.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.