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SubjectRe: [PATCH v3 0/6] ATS capability support for Intel IOMMU
On Thu, Feb 12, 2009 at 08:50:32PM +0800, Yu Zhao wrote:
> 2, avoid using pci_find_ext_capability every time when reading ATS
> Invalidate Queue Depth (Matthew Wilcox)

er ... I didn't say it was a problem. I said I couldn't tell if it was a
problem. There's no point in taking up an extra 4 bytes per pci_dev if
it's not a performance problem. How often do we query the queue depth?
Is this something a device driver will call once per device and then
remember for itself, or only use at setup? Or is it something we call
every millisecond?

--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."


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