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From: Arnd Bergmann <arnd@arndb.de>
To: linuxppc-dev@ozlabs.org
Cc: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>,
	linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Linux Kernel Development <linux-kernel@vger.kernel.org>,
	Christoph Lameter <clameter@sgi.com>
Subject: Re: Slab allocators: Define common size limitations
Date: Wed, 16 May 2007 23:42:07 +0200	[thread overview]
Message-ID: <200705162342.08601.arnd@arndb.de> (raw)
In-Reply-To: <Pine.LNX.4.62.0705160855470.24080@pademelon.sonytel.be>

On Wednesday 16 May 2007, Geert Uytterhoeven wrote:
> What are the changes a large allocation will actually succeed?
> Is there an alignment rule for large allocations?
> 
> E.g. for one of the PS3 drivers I need a physically contiguous 256 KiB-aligned
> block of 256 KiB. Currently I'm using __alloc_bootmem() for that, but maybe
> kmalloc() becomes a suitable alternative now?

kmalloc is limited to 128KiB on most architectures. Normally there is no
need to use it anyway, just use __get_free_pages(). It will generally
succeed at early boot time, but not after the system has been running
for some time.

	Arnd <><

WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: linuxppc-dev@ozlabs.org
Cc: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>,
	Christoph Lameter <clameter@sgi.com>,
	linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Linux Kernel Development <linux-kernel@vger.kernel.org>
Subject: Re: Slab allocators: Define common size limitations
Date: Wed, 16 May 2007 23:42:07 +0200	[thread overview]
Message-ID: <200705162342.08601.arnd@arndb.de> (raw)
In-Reply-To: <Pine.LNX.4.62.0705160855470.24080@pademelon.sonytel.be>

On Wednesday 16 May 2007, Geert Uytterhoeven wrote:
> What are the changes a large allocation will actually succeed?
> Is there an alignment rule for large allocations?
> 
> E.g. for one of the PS3 drivers I need a physically contiguous 256 KiB-aligned
> block of 256 KiB. Currently I'm using __alloc_bootmem() for that, but maybe
> kmalloc() becomes a suitable alternative now?

kmalloc is limited to 128KiB on most architectures. Normally there is no
need to use it anyway, just use __get_free_pages(). It will generally
succeed at early boot time, but not after the system has been running
for some time.

	Arnd <><

WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: linuxppc-dev@ozlabs.org
Cc: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>,
	Christoph Lameter <clameter@sgi.com>,
	linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Linux Kernel Development <linux-kernel@vger.kernel.org>
Subject: Re: Slab allocators: Define common size limitations
Date: Wed, 16 May 2007 23:42:07 +0200	[thread overview]
Message-ID: <200705162342.08601.arnd@arndb.de> (raw)
In-Reply-To: <Pine.LNX.4.62.0705160855470.24080@pademelon.sonytel.be>

On Wednesday 16 May 2007, Geert Uytterhoeven wrote:
> What are the changes a large allocation will actually succeed?
> Is there an alignment rule for large allocations?
> 
> E.g. for one of the PS3 drivers I need a physically contiguous 256 KiB-aligned
> block of 256 KiB. Currently I'm using __alloc_bootmem() for that, but maybe
> kmalloc() becomes a suitable alternative now?

kmalloc is limited to 128KiB on most architectures. Normally there is no
need to use it anyway, just use __get_free_pages(). It will generally
succeed at early boot time, but not after the system has been running
for some time.

	Arnd <><

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  parent reply	other threads:[~2007-05-16 21:42 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-05-16  6:15 Slab allocators: Define common size limitations Christoph Lameter
2007-05-16  6:15 ` Christoph Lameter
2007-05-16  6:32 ` Andrew Morton
2007-05-16  6:32   ` Andrew Morton
2007-05-16  6:39   ` David Miller
2007-05-16  6:39     ` David Miller, Andrew Morton
2007-05-16  6:58 ` Geert Uytterhoeven
2007-05-16  6:58   ` Geert Uytterhoeven
2007-05-16  6:58   ` Geert Uytterhoeven
2007-05-16  7:02   ` David Miller
2007-05-16  7:02     ` David Miller, Geert Uytterhoeven
2007-05-16  7:02     ` David Miller
2007-05-16 17:41   ` Christoph Lameter
2007-05-16 17:41     ` Christoph Lameter
2007-05-16 17:41     ` Christoph Lameter
2007-05-16 21:42   ` Arnd Bergmann [this message]
2007-05-16 21:42     ` Arnd Bergmann
2007-05-16 21:42     ` Arnd Bergmann
2007-05-17  8:45     ` Geert Uytterhoeven
2007-05-17  8:45       ` Geert Uytterhoeven
2007-05-17  8:45       ` Geert Uytterhoeven

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