From: Christoph Lameter <cl@linux-foundation.org>
To: Nitin Gupta <ngupta@vflare.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, linux-mm-cc@laptop.org
Subject: Re: [PATCH 1/4] compcache: xvmalloc memory allocator
Date: Wed, 26 Aug 2009 12:07:47 -0400 (EDT) [thread overview]
Message-ID: <alpine.DEB.1.10.0908261204400.9933@gentwo.org> (raw)
In-Reply-To: <4A92EBB4.1070101@vflare.org>
On Tue, 25 Aug 2009, Nitin Gupta wrote:
> PFNs are 32-bit on all archs while for 'struct page *', we require 32-bit or
> 64-bit depending on arch. ramzswap allocates a table entry <pagenum, offset>
> corresponding to every swap slot. So, the size of table will unnecessarily
> increase on 64-bit archs. Same is the argument for xvmalloc free list sizes.
Wrong. PFNs must be longer than 32 bit otherwise a system cannot
address more than 2^12 + 2^32 = 2^44 => 16TB.
The type used for PFNs is unsigned long which are 64 bit on 64 bit platforms.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Lameter <cl@linux-foundation.org>
To: Nitin Gupta <ngupta@vflare.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, linux-mm-cc@laptop.org
Subject: Re: [PATCH 1/4] compcache: xvmalloc memory allocator
Date: Wed, 26 Aug 2009 12:07:47 -0400 (EDT) [thread overview]
Message-ID: <alpine.DEB.1.10.0908261204400.9933@gentwo.org> (raw)
In-Reply-To: <4A92EBB4.1070101@vflare.org>
On Tue, 25 Aug 2009, Nitin Gupta wrote:
> PFNs are 32-bit on all archs while for 'struct page *', we require 32-bit or
> 64-bit depending on arch. ramzswap allocates a table entry <pagenum, offset>
> corresponding to every swap slot. So, the size of table will unnecessarily
> increase on 64-bit archs. Same is the argument for xvmalloc free list sizes.
Wrong. PFNs must be longer than 32 bit otherwise a system cannot
address more than 2^12 + 2^32 = 2^44 => 16TB.
The type used for PFNs is unsigned long which are 64 bit on 64 bit platforms.
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next prev parent reply other threads:[~2009-08-26 16:08 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-24 4:37 [PATCH 1/4] compcache: xvmalloc memory allocator Nitin Gupta
2009-08-24 4:37 ` Nitin Gupta
2009-08-24 17:33 ` Pekka Enberg
2009-08-24 17:33 ` Pekka Enberg
2009-08-24 17:52 ` Nitin Gupta
2009-08-24 17:52 ` Nitin Gupta
2009-08-24 18:08 ` Pekka Enberg
2009-08-24 18:08 ` Pekka Enberg
2009-08-24 18:11 ` Nitin Gupta
2009-08-24 18:11 ` Nitin Gupta
2009-08-24 18:27 ` Pekka Enberg
2009-08-24 18:27 ` Pekka Enberg
2009-08-24 18:40 ` Nitin Gupta
2009-08-24 18:40 ` Nitin Gupta
2009-08-24 19:36 ` Nitin Gupta
2009-08-24 19:36 ` Nitin Gupta
2009-08-24 19:43 ` Pekka Enberg
2009-08-24 19:43 ` Pekka Enberg
2009-08-24 21:16 ` Nitin Gupta
2009-08-24 21:16 ` Nitin Gupta
2009-08-25 4:26 ` Pekka Enberg
2009-08-25 4:26 ` Pekka Enberg
2009-08-24 20:39 ` Hugh Dickins
2009-08-24 20:39 ` Hugh Dickins
2009-08-24 21:16 ` Nitin Gupta
2009-08-24 21:16 ` Nitin Gupta
2009-08-24 21:46 ` Hugh Dickins
2009-08-24 21:46 ` Hugh Dickins
2009-08-25 14:52 ` Nitin Gupta
2009-08-25 14:52 ` Nitin Gupta
2009-08-25 19:03 ` Nitin Gupta
2009-08-25 19:03 ` Nitin Gupta
2009-08-26 16:10 ` Christoph Lameter
2009-08-26 16:10 ` Christoph Lameter
2009-08-26 16:17 ` Nitin Gupta
2009-08-26 16:17 ` Nitin Gupta
2009-08-26 16:19 ` Pekka Enberg
2009-08-26 16:19 ` Pekka Enberg
2009-08-26 16:07 ` Christoph Lameter [this message]
2009-08-26 16:07 ` Christoph Lameter
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