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authorAlex Williamson <alex.williamson@redhat.com>2015-02-06 14:19:12 -0700
committerAlex Williamson <alex.williamson@redhat.com>2015-02-06 14:19:12 -0700
commitc5e6688752c25434d71920bc969f9fab60353c5e (patch)
tree176ad1355f26bc2542e320471ab1691400c0974c /Documentation/arm
parentbabbf1760970f141eb4021288ce0fb7196bc1a23 (diff)
downloadlinux-c5e6688752c25434d71920bc969f9fab60353c5e.tar.bz2
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>
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