On Thu, 2015-04-09 at 10:44 +0300, Purcareata Bogdan wrote:

So at this point I was getting kinda frustrated so I decided to measure
the time spend in kvm_mpic_write and kvm_mpic_read. I assumed these were
the main entry points in the in-kernel MPIC and were basically executed
while holding the spinlock. The scenario was the same - 24 VCPUs guest,
with 24 virtio+vhost interfaces, only this time I ran 24 ping flood
threads to another board instead of netperf. I assumed this would impose
a heavier stress.

The latencies look pretty ok, around 1-2 us on average, with the max
shown below:

.kvm_mpic_read	14.560
.kvm_mpic_write	12.608

Those are also microseconds. This was run for about 15 mins.

What about other entry points such as kvm_set_msi() and
kvmppc_mpic_set_epr()?

-Scott