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From: nicolas.ferre@atmel.com (Nicolas Ferre)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] net/macb: Use dmapool to align descriptors on 64bits
Date: Tue, 4 Dec 2012 18:18:54 +0100	[thread overview]
Message-ID: <50BE307E.9090904@atmel.com> (raw)
In-Reply-To: <1354543290.7030.26.camel@deadeye.wl.decadent.org.uk>

On 12/03/2012 03:01 PM, Ben Hutchings :
> On Mon, 2012-12-03 at 13:15 +0100, Nicolas Ferre wrote:
>> Depending on datapath, some revisions of GEM need
>> 64bits aligned descriptors. Use dmapool to allocate
>> these descriptors.
>> Note that different size between RX and TX rings
>> leads to the creation of two pools.
>>
>> Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
> [...]
> 
> dma_alloc_coherent() allocates whole pages, which I think is quite
> enough alignment.  You can't save memory by doing this, since each pool
> needs at least one page.  So what is this change meant to achieve?

Well... I guess we can forget this patch then ;-)

Thanks, best regards,
-- 
Nicolas Ferre

WARNING: multiple messages have this Message-ID (diff)
From: Nicolas Ferre <nicolas.ferre@atmel.com>
To: Ben Hutchings <bhutchings@solarflare.com>
Cc: "David S. Miller" <davem@davemloft.net>, <netdev@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>,
	Joachim Eastwood <manabian@gmail.com>,
	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Subject: Re: [PATCH] net/macb: Use dmapool to align descriptors on 64bits
Date: Tue, 4 Dec 2012 18:18:54 +0100	[thread overview]
Message-ID: <50BE307E.9090904@atmel.com> (raw)
In-Reply-To: <1354543290.7030.26.camel@deadeye.wl.decadent.org.uk>

On 12/03/2012 03:01 PM, Ben Hutchings :
> On Mon, 2012-12-03 at 13:15 +0100, Nicolas Ferre wrote:
>> Depending on datapath, some revisions of GEM need
>> 64bits aligned descriptors. Use dmapool to allocate
>> these descriptors.
>> Note that different size between RX and TX rings
>> leads to the creation of two pools.
>>
>> Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
> [...]
> 
> dma_alloc_coherent() allocates whole pages, which I think is quite
> enough alignment.  You can't save memory by doing this, since each pool
> needs at least one page.  So what is this change meant to achieve?

Well... I guess we can forget this patch then ;-)

Thanks, best regards,
-- 
Nicolas Ferre

  reply	other threads:[~2012-12-04 17:18 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-12-03 12:15 [PATCH] net/macb: Use dmapool to align descriptors on 64bits Nicolas Ferre
2012-12-03 12:15 ` Nicolas Ferre
2012-12-03 14:01 ` Ben Hutchings
2012-12-03 14:01   ` Ben Hutchings
2012-12-04 17:18   ` Nicolas Ferre [this message]
2012-12-04 17:18     ` Nicolas Ferre

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