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author | 2015-02-06 14:19:12 -0700 | |
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committer | 2015-02-06 14:19:12 -0700 | |
commit | c5e6688752c25434d71920bc969f9fab60353c5e (patch) | |
tree | 176ad1355f26bc2542e320471ab1691400c0974c /drivers/vfio/vfio_iommu_type1.c | |
parent | vfio/type1: Chunk contiguous reserved/invalid page mappings (diff) | |
download | linux-c5e6688752c25434d71920bc969f9fab60353c5e.tar.gz linux-c5e6688752c25434d71920bc969f9fab60353c5e.tar.bz2 linux-c5e6688752c25434d71920bc969f9fab60353c5e.zip |
vfio/type1: Add conditional rescheduling
IOMMU operations can be expensive and it's not very difficult for a
user to give us a lot of work to do for a map or unmap operation.
Killing a large VM will vfio assigned devices can result in soft
lockups and IOMMU tracing shows that we can easily spend 80% of our
time with need-resched set. A sprinkling of conf_resched() calls
after map and unmap calls has a very tiny affect on performance
while resulting in traces with <1% of calls overflowing into needs-
resched.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'drivers/vfio/vfio_iommu_type1.c')
-rw-r--r-- | drivers/vfio/vfio_iommu_type1.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 35c90089478e..57d8c37a002b 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -351,8 +351,10 @@ static void vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma) domain = d = list_first_entry(&iommu->domain_list, struct vfio_domain, next); - list_for_each_entry_continue(d, &iommu->domain_list, next) + list_for_each_entry_continue(d, &iommu->domain_list, next) { iommu_unmap(d->domain, dma->iova, dma->size); + cond_resched(); + } while (iova < end) { size_t unmapped, len; @@ -384,6 +386,8 @@ static void vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma) unmapped >> PAGE_SHIFT, dma->prot, false); iova += unmapped; + + cond_resched(); } vfio_lock_acct(-unlocked); @@ -528,6 +532,8 @@ static int vfio_iommu_map(struct vfio_iommu *iommu, dma_addr_t iova, map_try_harder(d, iova, pfn, npage, prot)) goto unwind; } + + cond_resched(); } return 0; |