From: Andi Kleen <ak@suse.de>
To: Christoph Lameter <clameter@sgi.com>
Cc: pj@sgi.com, linux-mm@kvack.org, akpm@osdl.org
Subject: Re: Radical idea
Date: Sun, 17 Sep 2006 20:13:27 +0200 [thread overview]
Message-ID: <200609172013.27095.ak@suse.de> (raw)
In-Reply-To: <Pine.LNX.4.64.0609170543590.14541@schroedinger.engr.sgi.com>
>
> And yes it would only work the DMA32 problems mentioned by Andi could be
> addressed. Do we really need DMA32 in modern systems with IOMMUs?
We do.
In fact we still need DMA-without-32 on most systems (after all most users
still want to use their floppy occasionally and it is needed for a few other
devices too)
> Isnt this a transitionary problem that will go away?
Not any time soon.
> So lets say we have one of those systems without IOMMU. Then we only have
> a problem for a class of NUMA systems that have:
>
> 1. Memory beyond 4GB
>
> and
>
> 2. Per node memory less than 4GB. Otherwise DMA32 is only on node 0.
>
> Isnt this a fairly small group of systems?
I don't think so. e.g. a lot of quad opteron configurations come with 1 or 2GB per
socket (= node)
Anyways, even if it was uncommon we couldn't just break it. So i'm not sure what
the point of your "popularity contest" is?
-Andi
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prev parent reply other threads:[~2006-09-17 18:13 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-17 13:01 Radical idea Christoph Lameter
2006-09-17 13:20 ` Paul Jackson
2006-09-17 18:13 ` Andi Kleen [this message]
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