From: Peter Zijlstra <peterz@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Micha__ Nazarewicz <m.nazarewicz@samsung.com>,
linux-kernel@vger.kernel.org, m.szyprowski@samsung.com,
kyungmin.park@samsung.com, linux-mm@kvack.org
Subject: Re: [PATCH] Physical Memory Management [0/1]
Date: Thu, 14 May 2009 19:10:00 +0200 [thread overview]
Message-ID: <1242321000.6642.1456.camel@laptop> (raw)
In-Reply-To: <20090514100718.d8c20b64.akpm@linux-foundation.org>
On Thu, 2009-05-14 at 10:07 -0700, Andrew Morton wrote:
> On Thu, 14 May 2009 15:04:55 +0200
> Micha__ Nazarewicz <m.nazarewicz@samsung.com> wrote:
>
> > On Thu, 14 May 2009 14:05:02 +0200, Peter Zijlstra wrote:
> > > And who says your pre-allocated pool won't fragment with repeated PMM
> > > use?
> >
> > Yes, this is a good question. What's more, there's no good answer. ;)
> >
>
> We do have capability in page reclaim to deliberately free up
> physically contiguous pages (known as "lumpy reclaim").
>
> It would be interesting were someone to have a go at making that
> available to userspace: ask the kernel to give you 1MB of physically
> contiguous memory. There are reasons why this can fail, but migrating
> pages can be used to improve the success rate, and userspace can be
> careful to not go nuts using mlock(), etc.
>
> The returned memory would of course need to be protected from other
> reclaim/migration/etc activity.
I thought we already exposed this, its called hugetlbfs ;-)
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Micha__ Nazarewicz <m.nazarewicz@samsung.com>,
linux-kernel@vger.kernel.org, m.szyprowski@samsung.com,
kyungmin.park@samsung.com, linux-mm@kvack.org
Subject: Re: [PATCH] Physical Memory Management [0/1]
Date: Thu, 14 May 2009 19:10:00 +0200 [thread overview]
Message-ID: <1242321000.6642.1456.camel@laptop> (raw)
In-Reply-To: <20090514100718.d8c20b64.akpm@linux-foundation.org>
On Thu, 2009-05-14 at 10:07 -0700, Andrew Morton wrote:
> On Thu, 14 May 2009 15:04:55 +0200
> Micha__ Nazarewicz <m.nazarewicz@samsung.com> wrote:
>
> > On Thu, 14 May 2009 14:05:02 +0200, Peter Zijlstra wrote:
> > > And who says your pre-allocated pool won't fragment with repeated PMM
> > > use?
> >
> > Yes, this is a good question. What's more, there's no good answer. ;)
> >
>
> We do have capability in page reclaim to deliberately free up
> physically contiguous pages (known as "lumpy reclaim").
>
> It would be interesting were someone to have a go at making that
> available to userspace: ask the kernel to give you 1MB of physically
> contiguous memory. There are reasons why this can fail, but migrating
> pages can be used to improve the success rate, and userspace can be
> careful to not go nuts using mlock(), etc.
>
> The returned memory would of course need to be protected from other
> reclaim/migration/etc activity.
I thought we already exposed this, its called hugetlbfs ;-)
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next prev parent reply other threads:[~2009-05-14 17:10 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-13 9:26 [PATCH] Physical Memory Management [0/1] Michał Nazarewicz
2009-05-13 9:27 ` [PATCH] Physical Memory Management [1/1] Michał Nazarewicz
2009-05-13 22:11 ` [PATCH] Physical Memory Management [0/1] Andrew Morton
2009-05-13 22:11 ` Andrew Morton
2009-05-14 9:00 ` Michał Nazarewicz
2009-05-14 9:00 ` Michał Nazarewicz
2009-05-14 11:20 ` Peter Zijlstra
2009-05-14 11:20 ` Peter Zijlstra
2009-05-14 11:48 ` Michał Nazarewicz
2009-05-14 11:48 ` Michał Nazarewicz
2009-05-14 12:05 ` Peter Zijlstra
2009-05-14 12:05 ` Peter Zijlstra
2009-05-14 13:04 ` Michał Nazarewicz
2009-05-14 13:04 ` Michał Nazarewicz
2009-05-14 17:07 ` Andrew Morton
2009-05-14 17:07 ` Andrew Morton
2009-05-14 17:10 ` Peter Zijlstra [this message]
2009-05-14 17:10 ` Peter Zijlstra
2009-05-15 10:06 ` Michał Nazarewicz
2009-05-15 10:06 ` Michał Nazarewicz
2009-05-15 10:18 ` Andi Kleen
2009-05-15 10:18 ` Andi Kleen
2009-05-15 10:47 ` Michał Nazarewicz
2009-05-15 10:47 ` Michał Nazarewicz
2009-05-15 11:03 ` Peter Zijlstra
2009-05-15 11:03 ` Peter Zijlstra
2009-05-15 11:11 ` Michał Nazarewicz
2009-05-15 11:11 ` Michał Nazarewicz
2009-05-15 11:26 ` Andi Kleen
2009-05-15 11:26 ` Andi Kleen
2009-05-15 12:05 ` Michał Nazarewicz
2009-05-15 12:05 ` Michał Nazarewicz
2009-05-14 19:33 ` Andi Kleen
2009-05-14 19:33 ` Andi Kleen
-- strict thread matches above, loose matches on Subject: below --
2009-05-13 9:23 Michał Nazarewicz
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