From: Rik van Riel <riel@redhat.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH] MM: Support more pagesizes for MAP_HUGETLB/SHM_HUGETLB v2
Date: Wed, 13 Jun 2012 16:38:15 -0400 [thread overview]
Message-ID: <4FD8FA37.10103@redhat.com> (raw)
In-Reply-To: <20120613203103.GG11413@one.firstfloor.org>
On 06/13/2012 04:31 PM, Andi Kleen wrote:
> On Wed, Jun 13, 2012 at 04:24:47PM -0400, Rik van Riel wrote:
>> This would also be useful for emulators such as qemu-kvm,
>> which want the guest memory to be 2MB aligned.
>
> hugetlbfs does implicit align, so right now I mash
> the two together and use up many of the remaining bits
>
> If you want align different than page sizes you may need
> to go 64bits with the flags.
All alignment is a power of two, so six bits should
be enough for up to 2^64 pages :)
> Is there a use case for alignment independent of page sizes?
No, but page size differs per architecture and it
would be nice if we could share arch_get_unmapped_area
and related code in mm/, instead of every architecture
having its own.
In fact, that is what I am working on right now, and
my current road block is the page colouring code :)
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WARNING: multiple messages have this Message-ID (diff)
From: Rik van Riel <riel@redhat.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH] MM: Support more pagesizes for MAP_HUGETLB/SHM_HUGETLB v2
Date: Wed, 13 Jun 2012 16:38:15 -0400 [thread overview]
Message-ID: <4FD8FA37.10103@redhat.com> (raw)
In-Reply-To: <20120613203103.GG11413@one.firstfloor.org>
On 06/13/2012 04:31 PM, Andi Kleen wrote:
> On Wed, Jun 13, 2012 at 04:24:47PM -0400, Rik van Riel wrote:
>> This would also be useful for emulators such as qemu-kvm,
>> which want the guest memory to be 2MB aligned.
>
> hugetlbfs does implicit align, so right now I mash
> the two together and use up many of the remaining bits
>
> If you want align different than page sizes you may need
> to go 64bits with the flags.
All alignment is a power of two, so six bits should
be enough for up to 2^64 pages :)
> Is there a use case for alignment independent of page sizes?
No, but page size differs per architecture and it
would be nice if we could share arch_get_unmapped_area
and related code in mm/, instead of every architecture
having its own.
In fact, that is what I am working on right now, and
my current road block is the page colouring code :)
next prev parent reply other threads:[~2012-06-13 20:39 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-12 23:13 [PATCH] MM: Support more pagesizes for MAP_HUGETLB/SHM_HUGETLB v2 Andi Kleen
2012-06-12 23:13 ` Andi Kleen
2012-06-13 20:24 ` Rik van Riel
2012-06-13 20:24 ` Rik van Riel
2012-06-13 20:31 ` Andi Kleen
2012-06-13 20:31 ` Andi Kleen
2012-06-13 20:38 ` Rik van Riel [this message]
2012-06-13 20:38 ` Rik van Riel
2012-06-15 10:35 ` Michal Hocko
2012-06-15 10:35 ` Michal Hocko
2012-06-16 7:28 ` Kamezawa Hiroyuki
2012-06-16 7:28 ` Kamezawa Hiroyuki
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