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.
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next prev parent reply other threads:[~2007-05-08 23:23 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-28 4:43 Rik van Riel
2007-05-04 10:53 ` Nick Piggin
2007-05-04 11:58 ` Rik van Riel
2007-05-04 23:49 ` Nick Piggin
2007-05-04 16:04 ` Ulrich Drepper
2007-05-04 23:47 ` Nick Piggin
2007-05-05 0:10 ` Ulrich Drepper
2007-05-06 22:43 ` Rik van Riel
2007-05-07 2:42 ` Ulrich Drepper
2007-05-07 4:56 ` Rik van Riel
2007-05-07 4:53 ` Ulrich Drepper
2007-05-07 16:51 ` Rik van Riel
2007-05-08 6:12 ` Nick Piggin
2007-05-08 14:59 ` Rik van Riel
2007-05-08 23:23 ` Nick Piggin [this message]
2007-05-08 18:35 ` Jakub Jelinek
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
2007-05-09 17:15 ` Ulrich Drepper
2007-05-09 16:38 ` [PATCH] MM: implement MADV_FREE lazy freeing of anonymous memory Hugh Dickins
2007-05-29 16:59 ` Rik van Riel
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