From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Rik van Riel <riel@redhat.com>
Cc: Ulrich Drepper <drepper@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jakub Jelinek <jakub@redhat.com>
Subject: Re: [PATCH] MM: implement MADV_FREE lazy freeing of anonymous memory
Date: Wed, 09 May 2007 09:23:09 +1000 [thread overview]
Message-ID: <4641065D.6060403@yahoo.com.au> (raw)
In-Reply-To: <4640906B.2020301@redhat.com>
Rik van Riel wrote:
> Nick Piggin wrote:
>
>> We have percpu and cache affine page allocators, so when
>> userspace just frees a page, it is likely to be cache hot, so
>> we want to free it up so it can be reused by this CPU ASAP.
>> Likewise, when we newly allocate a page, we want it to be one
>> that is cache hot on this CPU.
>
>
> Actually, isn't the clear page function capable of doing
> some magic, when it writes all zeroes into the page, that
> causes the zeroes to just live in CPU cache without the old
> data ever being loaded from RAM?
>
> That would sure be faster than touching RAM. Not sure if
> we use/trigger that kind of magic, though :)
>
powerpc has and uses an instruction to zero a full cacheline, yes.
Not sure about x86-64 CPUs... I don't think they can do it.
--
SUSE Labs, Novell Inc.
WARNING: multiple messages have this Message-ID (diff)
From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Rik van Riel <riel@redhat.com>
Cc: Ulrich Drepper <drepper@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jakub Jelinek <jakub@redhat.com>
Subject: Re: [PATCH] MM: implement MADV_FREE lazy freeing of anonymous memory
Date: Wed, 09 May 2007 09:23:09 +1000 [thread overview]
Message-ID: <4641065D.6060403@yahoo.com.au> (raw)
In-Reply-To: <4640906B.2020301@redhat.com>
Rik van Riel wrote:
> Nick Piggin wrote:
>
>> We have percpu and cache affine page allocators, so when
>> userspace just frees a page, it is likely to be cache hot, so
>> we want to free it up so it can be reused by this CPU ASAP.
>> Likewise, when we newly allocate a page, we want it to be one
>> that is cache hot on this CPU.
>
>
> Actually, isn't the clear page function capable of doing
> some magic, when it writes all zeroes into the page, that
> causes the zeroes to just live in CPU cache without the old
> data ever being loaded from RAM?
>
> That would sure be faster than touching RAM. Not sure if
> we use/trigger that kind of magic, though :)
>
powerpc has and uses an instruction to zero a full cacheline, yes.
Not sure about x86-64 CPUs... I don't think they can do it.
--
SUSE Labs, Novell Inc.
--
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>
next prev parent reply other threads:[~2007-05-08 23:24 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-28 4:43 [PATCH] MM: implement MADV_FREE lazy freeing of anonymous memory Rik van Riel
2007-05-04 10:53 ` Nick Piggin
2007-05-04 10:53 ` Nick Piggin
2007-05-04 11:58 ` Rik van Riel
2007-05-04 11:58 ` Rik van Riel
2007-05-04 23:49 ` Nick Piggin
2007-05-04 23:49 ` Nick Piggin
2007-05-04 16:04 ` Ulrich Drepper
2007-05-04 23:47 ` Nick Piggin
2007-05-04 23:47 ` Nick Piggin
2007-05-05 0:10 ` Ulrich Drepper
2007-05-06 22:43 ` Rik van Riel
2007-05-06 22:43 ` Rik van Riel
2007-05-07 2:42 ` Ulrich Drepper
2007-05-07 2:42 ` Ulrich Drepper
2007-05-07 4:56 ` Rik van Riel
2007-05-07 4:56 ` Rik van Riel
2007-05-07 4:53 ` Ulrich Drepper
2007-05-07 4:53 ` Ulrich Drepper
2007-05-07 16:51 ` Rik van Riel
2007-05-07 16:51 ` Rik van Riel
2007-05-08 6:12 ` Nick Piggin
2007-05-08 6:12 ` Nick Piggin
2007-05-08 14:59 ` Rik van Riel
2007-05-08 14:59 ` Rik van Riel
2007-05-08 23:23 ` Nick Piggin [this message]
2007-05-08 23:23 ` Nick Piggin
2007-05-08 18:35 ` Jakub Jelinek
2007-05-08 18:35 ` Jakub Jelinek
2007-05-08 23:43 ` Nick Piggin
2007-05-08 23:43 ` Nick Piggin
2007-05-08 3:51 ` [PATCH] stub MADV_FREE implementation Rik van Riel
2007-05-08 23:05 ` Andrew Morton
2007-05-08 23:05 ` Andrew Morton
2007-05-09 17:15 ` Ulrich Drepper
2007-05-09 17:15 ` Ulrich Drepper
2007-05-09 16:38 ` [PATCH] MM: implement MADV_FREE lazy freeing of anonymous memory Hugh Dickins
2007-05-09 16:38 ` Hugh Dickins
2007-05-29 16:59 ` Rik van Riel
2007-05-29 16:59 ` Rik van Riel
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=4641065D.6060403@yahoo.com.au \
--to=nickpiggin@yahoo.com.au \
--cc=akpm@linux-foundation.org \
--cc=drepper@redhat.com \
--cc=jakub@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=riel@redhat.com \
--cc=torvalds@linux-foundation.org \
/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.