From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Andi Kleen <ak@suse.de>
Cc: Jeff Garzik <jgarzik@pobox.com>,
Andrew Grover <andrew.grover@intel.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
john.ronciak@intel.com, christopher.leech@intel.com
Subject: Re: [RFC] [PATCH 0/3] ioat: DMA engine support
Date: Thu, 24 Nov 2005 00:05:40 +0000 [thread overview]
Message-ID: <1132790740.13095.53.camel@localhost.localdomain> (raw)
In-Reply-To: <20051123223007.GA5921@wotan.suse.de>
On Mer, 2005-11-23 at 23:30 +0100, Andi Kleen wrote:
> Another proposal was swiotlb.
I was hoping Intel might have rediscovered the IOMMU by then and be back
on feature parity with the VAX 11/750
>
> But it's not clear it's a good idea: a lot of these applications prefer to
> have the target in cache. And IOAT will force it out of cache.
This is true for some cases but not all for iotlb
CPU generated data going out that won't be rewritten immediately should
be a cheap path not needing the cache. Incoming data would invalidate
the cache anyway if it arrives by DMA so the ioat would move it
asynchronously of the CPU without cache harm
Might also be interesting to use one half of a hypedthread CPU as a
copier using the streaming instructions, might be better than turning it
off to improve performance ?
Alan
next prev parent reply other threads:[~2005-11-24 0:05 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-23 20:26 [RFC] [PATCH 0/3] ioat: DMA engine support Andrew Grover
2005-11-23 22:06 ` Jeff Garzik
2005-11-23 22:30 ` Andi Kleen
2005-11-23 23:02 ` Jeff Garzik
2005-11-24 0:05 ` Alan Cox [this message]
2005-11-23 23:36 ` Jeff Garzik
2005-11-24 0:17 ` Benjamin LaHaise
2005-11-24 0:50 ` David S. Miller
2005-11-24 6:50 ` Andi Kleen
2005-11-24 15:24 ` Avi Kivity
2005-11-24 15:29 ` Andi Kleen
2005-11-24 15:35 ` Avi Kivity
2005-11-24 15:37 ` Andi Kleen
2005-11-23 22:54 ` Alan Cox
2005-11-23 22:56 ` Jeff Garzik
2005-12-08 22:13 ` Kumar Gala
2005-12-08 22:23 ` Roland Dreier
2005-12-08 22:42 ` Alan Cox
2005-12-09 7:12 ` Evgeniy Polyakov
2005-11-23 22:45 ` Jeff Garzik
2005-12-02 17:06 ` Jon Mason
2005-11-23 22:53 ` Jeff Garzik
2005-11-23 23:02 ` Alan Cox
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