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From: Anton Blanchard <anton@samba.org>
To: "David S. Miller" <davem@redhat.com>
Cc: davidm@hpl.hp.com, davidm@napali.hpl.hp.com,
	manfred@colorfullife.com, axboe@suse.de,
	linux-kernel@vger.kernel.org
Subject: Re: problem with blk_queue_bounce_limit()
Date: Sun, 15 Jun 2003 17:06:11 +1000	[thread overview]
Message-ID: <20030615070611.GE31148@krispykreme> (raw)
In-Reply-To: <20030607.001140.08328499.davem@redhat.com>

 
>    But you're creating a new mapping for the old buffer.  What if you had
>    a DMA API implementation which consolidates multiple mapping attempts
>    of the same buffer into a single mapping entry (along with a reference
>    count)?  That would break the workaround.
>    
> I hope nobody is doing this, it would probably break other things
> we haven't considered yet.

Dave, we talked about this ages ago as a possible alternative to skb
recycling and persistent IOMMU mappings for those skbs.

Unfortunately you need a hash to map from all of memory to a pci bus
address for each host bridge (well IOMMU), and so far I cant think of
anything that wouldnt chew gobs of RAM.

Anton

  parent reply	other threads:[~2003-06-15  6:53 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-06-05  6:42 problem with blk_queue_bounce_limit() David Mosberger
2003-06-05  7:20 ` David S. Miller
2003-06-06  6:42   ` David Mosberger
2003-06-06  6:45     ` David S. Miller
2003-06-06  6:54       ` David Mosberger
2003-06-06  7:08         ` David S. Miller
2003-06-06  6:52     ` David S. Miller
2003-06-06  7:19       ` David Mosberger
2003-06-06  7:32         ` David S. Miller
2003-06-06  7:44           ` Christoph Hellwig
2003-06-06  7:43             ` David S. Miller
2003-06-06  7:51               ` Christoph Hellwig
2003-06-06 20:13           ` David Mosberger
2003-06-07  6:44             ` David S. Miller
2003-06-07  7:05               ` David Mosberger
2003-06-07  7:11                 ` David S. Miller
2003-06-10 20:01                   ` David Mosberger
2003-06-12  6:47                     ` David S. Miller
2003-06-15  7:06                   ` Anton Blanchard [this message]
2003-06-15  7:11                     ` David S. Miller
2003-06-15  8:04                       ` Anton Blanchard
2003-06-15  8:18                         ` David S. Miller
2003-06-07  7:20               ` David Mosberger
2003-06-07  7:19                 ` David S. Miller
2003-06-07  9:44                 ` Russell King
2003-06-07  9:47                   ` David S. Miller
2003-06-07 13:23                     ` Christoph Hellwig
2003-06-10 20:24                 ` David Mosberger
2003-06-06 18:06 James Bottomley

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