From: cody <mail.kai.huang@gmail.com>
To: David Woodhouse <dwmw2@infradead.org>
Cc: Chris Wright <chrisw@sous-sol.org>,
Roland Dreier <roland@purestorage.com>,
Alex Williamson <alex.williamson@redhat.com>,
iommu@lists.linux-foundation.org, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org, ddutile@redhat.com
Subject: Re: [PATCH] intel-iommu: Default to non-coherent for domains unattached to iommus
Date: Mon, 14 Nov 2011 23:12:11 -0800 [thread overview]
Message-ID: <4EC210CB.1010409@gmail.com> (raw)
In-Reply-To: <1321060841.2006.35.camel@shinybook.infradead.org>
On 11/11/2011 05:20 PM, David Woodhouse wrote:
> On Fri, 2011-11-11 at 17:08 -0800, Chris Wright wrote:
>
>> All the stale PTE issues I've encountered in the past have turned into
>> fixed sw bugs (perhaps it's since been fixed?). Also, I thought with
>> Coherency On/Off it's only effecting the use of clflush, not IOTLB or
>> Context Entry cache flushing (invalidations).
>>
> Yeah, it's supposed to be *just* clflush. Nevertheless, I can imagine it
> being screwed up and there actually being a buffer in the chipset too.
> We certainly made that mistake with the graphics engine in some cases...
>
>
>> On a slightly separate, but performance related note...have you ever
>> tried using the hw queue? Currently we only have a sw queue, but the
>> submission path for invalidations doesn't really queue (unless I missed
>> it). It seems to pull from the software queue and submit/wait,
>> submit/wait...Seems simple enough to submit the whole queue and then
>> issue the wait.
>>
> I have a feeling we trigger errata if we do that — although if we're
> only doing it for an emulated IOMMU that shouldn't be an issue.
>
>
What does the emulated IOMMU here? Does it mean the emulated IOMMU
exposed to guest VM?
next prev parent reply other threads:[~2011-11-14 15:12 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-11 22:49 [PATCH] intel-iommu: Default to non-coherent for domains unattached to iommus Alex Williamson
2011-11-12 0:17 ` Chris Wright
2011-11-12 0:37 ` David Woodhouse
2011-11-12 0:45 ` Chris Wright
2011-11-12 0:47 ` Chris Wright
2011-11-12 0:51 ` David Woodhouse
2011-11-12 0:58 ` Chris Wright
2011-11-12 1:03 ` David Woodhouse
2011-11-12 0:46 ` Roland Dreier
2011-11-12 0:51 ` Chris Wright
2011-11-12 0:55 ` David Woodhouse
2011-11-12 1:08 ` Chris Wright
2011-11-12 1:20 ` David Woodhouse
2011-11-15 7:12 ` cody [this message]
2011-11-15 4:54 ` Chris Wright
2011-11-15 5:55 ` Kai Huang
2011-11-12 1:30 ` Roland Dreier
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