kvm: optimize out smp_mb after srcu_read_unlock
I noticed that srcu_read_lock/unlock both have a memory barrier, so just by moving srcu_read_unlock earlier we can get rid of one call to smp_mb() using smp_mb__after_srcu_read_unlock instead. Unsurprisingly, the gain is small but measureable using the unit test microbenchmark: before vmcall in the ballpark of 1410 cycles after vmcall in the ballpark of 1360 cycles Signed-off-by:Michael S. Tsirkin <mst@redhat.com> Signed-off-by:
Gleb Natapov <gleb@redhat.com>
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