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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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