On Fri, Oct 27, 2017 at 07:14:31PM +0300, Michael S. Tsirkin wrote:
> The one difference between lock+add and mfence is that lock+addl does
> not affect clflush, previous patches converted all uses of clflush to
> call mb(), such that changes to smp_mb won't affect it.
>
> Update mb/rmb/wmb on 32
mfence appears to be way slower than a locked instruction - let's use
lock+add unconditionally, as we always did on old 32-bit.
Results:
perf stat -r 10 -- ./virtio_ring_0_9 --sleep --host-affinity 0 --guest-affinity 0
Before:
0.922565990 seconds time elapsed
