Messages in this thread | | | Date | Thu, 31 Oct 2013 12:14:15 +0100 | From | Paolo Bonzini <> | Subject | Re: [PATCH RFC] kvm: optimize out smp_mb using srcu_read_unlock |
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Il 30/10/2013 20:09, Michael S. Tsirkin ha scritto: > 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(). > > Unsurprisingly, the gain is small but measureable using the unit test > microbenchmark: > before > vmcall 1407 > after > vmcall 1357 > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Across how many runs? Best or average or "all runs were in that ballpark", :) and what's the minimum/maximum before and after the patch?
As you say the benefit is not surprising, but the experiments should be documented properly.
Paolo
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