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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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