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authorMichael S. Tsirkin <mst@redhat.com>2012-06-24 19:24:26 +0300
committerAvi Kivity <avi@redhat.com>2012-06-25 12:37:21 +0300
commit8680b94b0e6046af2644c17313287ec0cb5843dc (patch)
treef86463519e93140de7e113dc4dfa88a8cc348c6a /kernel/irq
parent5eadf916dfa04c3c51397dbcb803ce8735bf191a (diff)
downloadblackbird-op-linux-8680b94b0e6046af2644c17313287ec0cb5843dc.tar.gz
blackbird-op-linux-8680b94b0e6046af2644c17313287ec0cb5843dc.zip
KVM: optimize ISR lookups
We perform ISR lookups twice: during interrupt injection and on EOI. Typical workloads only have a single bit set there. So we can avoid ISR scans by 1. counting bits as we set/clear them in ISR 2. on set, caching the injected vector number 3. on clear, invalidating the cache The real purpose of this is enabling PV EOI which needs to quickly validate the vector. But non PV guests also benefit: with this patch, and without interrupt nesting, apic_find_highest_isr will always return immediately without scanning ISR. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
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