From: Andi Kleen <ak@suse.de>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: William Lee Irwin III <wli@holomorphy.com>,
Anton Blanchard <anton@samba.org>,
sfr@ozlabs.org,
linuxppc64-dev <linuxppc64-dev@lists.linuxppc.org>,
Linux Kernel list <linux-kernel@vger.kernel.org>,
linux-scsi@vger.kernel.org
Subject: Re: [PATCH] [ppc64] watch IOMMU virtual merging
Date: Tue, 3 Aug 2004 00:20:00 +0200 [thread overview]
Message-ID: <20040802222000.GM25951@wotan.suse.de> (raw)
In-Reply-To: <1091483151.7389.78.camel@gaston>
On Tue, Aug 03, 2004 at 07:45:51AM +1000, Benjamin Herrenschmidt wrote:
[adding linux-scsi with full quote]
>
> Actually, we could tune the ratio between large allocs and small allocs,
> the real problem is the failure case. We can't really afford to break
> down a physical segment at the iommu level because that would increase
> the size of the SG list which can't be dealt at the upper level (we don't
> know how much space has been allocated and the HW may have limitations on
> the number of entries).
>
> What we really need is a way for drivers to return the BIO upstream and
> ask for a split in case of iommu allocation error, but I've been told that
> would be horribly complex...
Not very, according to James B. It just needs driver changes.
I would like to have it too.
-Andi
prev parent reply other threads:[~2004-08-02 22:20 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-08-02 16:44 Anton Blanchard
2004-08-02 17:08 ` William Lee Irwin III
2004-08-02 21:32 ` Anton Blanchard
2004-08-02 21:45 ` Benjamin Herrenschmidt
2004-08-02 22:20 ` Andi Kleen [this message]
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