Messages in this thread Patch in this message | | | From | Lu Baolu <> | Subject | [PATCH 2/4] iommu/vt-d: Avoid superfluous IOTLB tracking in lazy mode | Date | Thu, 16 Feb 2023 21:08:14 +0800 |
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From: Jacob Pan <jacob.jun.pan@linux.intel.com>
Intel IOMMU driver implements IOTLB flush queue with domain selective or PASID selective invalidations. In this case there's no need to track IOVA page range and sync IOTLBs, which may cause significant performance hit.
This patch adds a check to avoid IOVA gather page and IOTLB sync for the lazy path.
The performance difference on Sapphire Rapids 100Gb NIC is improved by the following (as measured by iperf send):
w/o this fix~48 Gbits/s. with this fix ~54 Gbits/s
Cc: <stable@vger.kernel.org> Fixes: 2a2b8eaa5b25 ("iommu: Handle freelists when using deferred flushing in iommu drivers") Reviewed-by: Robin Murphy <robin.murphy@arm.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Tested-by: Sanjay Kumar <sanjay.k.kumar@intel.com> Signed-off-by: Sanjay Kumar <sanjay.k.kumar@intel.com> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> Link: https://lore.kernel.org/r/20230209175330.1783556-1-jacob.jun.pan@linux.intel.com Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> --- drivers/iommu/intel/iommu.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 994dffa1db57..ce36a16efc97 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -4346,7 +4346,12 @@ static size_t intel_iommu_unmap(struct iommu_domain *domain, if (dmar_domain->max_addr == iova + size) dmar_domain->max_addr = iova; - iommu_iotlb_gather_add_page(domain, gather, iova, size); + /* + * We do not use page-selective IOTLB invalidation in flush queue, + * so there is no need to track page and sync iotlb. + */ + if (!iommu_iotlb_gather_queued(gather)) + iommu_iotlb_gather_add_page(domain, gather, iova, size); return size; } -- 2.34.1
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