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    Subject[PATCH 2/7] Intel pci: Speed up processing of the identity_mapping function
        When there are a large count of PCI devices, and the pass
    through option for iommu is set, much time is spent in the
    identity_mapping function hunting though the iommu domains to
    check if a specific device is "identity mapped".

    Speed up the function by checking the cached info to see if
    it's mapped to the static identity domain.

    Signed-off-by: Mike Travis <travis@sgi.com>
    ---
    drivers/pci/intel-iommu.c | 6 +++---
    1 file changed, 3 insertions(+), 3 deletions(-)

    --- linux.orig/drivers/pci/intel-iommu.c
    +++ linux/drivers/pci/intel-iommu.c
    @@ -2106,10 +2106,10 @@ static int identity_mapping(struct pci_d
    if (likely(!iommu_identity_mapping))
    return 0;

    + info = pdev->dev.archdata.iommu;
    + if (info && info != DUMMY_DEVICE_DOMAIN_INFO)
    + return (info->domain == si_domain);

    - list_for_each_entry(info, &si_domain->devices, link)
    - if (info->dev == pdev)
    - return 1;
    return 0;
    }

    --


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