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| author | Michael S. Tsirkin <mst@redhat.com> | 2013-11-04 21:36:25 +0100 |
|---|---|---|
| committer | Gleb Natapov <gleb@redhat.com> | 2013-11-06 08:32:31 +0100 |
| commit | 01b71917b55d28c09ade9fb8c683cf0d2aad1858 (patch) | |
| tree | 5ec0842876cd80c754c486dac1a810850d98ecd6 /arch/x86/include/asm/pvclock.h | |
| parent | srcu: API for barrier after srcu read unlock (diff) | |
| download | linux-01b71917b55d28c09ade9fb8c683cf0d2aad1858.tar.xz linux-01b71917b55d28c09ade9fb8c683cf0d2aad1858.zip | |
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>
Diffstat (limited to 'arch/x86/include/asm/pvclock.h')
0 files changed, 0 insertions, 0 deletions