On Tue, 10 Oct 2017 17:11:09 +1000
Nicholas Piggin <npiggin@xxxxxxxxx> wrote:
> For shared processor guests (e.g., KVM), add an idle polling mode rather
> than immediately returning to the hypervisor when the guest CPU goes
> idle.
>
> Test setup is a 2 socket POWER9 with 4 guests running, each with vCPUs
> equal to 1/2 of real of CPUs. Saturated each guest with tbench. Using
> polling idle gives about 1.4x throughput.
>
> Kernel compile speed was not changed significantly.
>
> Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
What should we do about this one?
> ---
> drivers/cpuidle/cpuidle-pseries.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/cpuidle/cpuidle-pseries.c b/drivers/cpuidle/cpuidle-pseries.c
> index e9b3853d93ea..16be7ad30fe1 100644
> --- a/drivers/cpuidle/cpuidle-pseries.c
> +++ b/drivers/cpuidle/cpuidle-pseries.c
> @@ -171,11 +171,17 @@ static struct cpuidle_state dedicated_states[] = {
> * States for shared partition case.
> */
> static struct cpuidle_state shared_states[] = {
> + { /* Snooze */
> + .name = "snooze",
> + .desc = "snooze",
> + .exit_latency = 0,
> + .target_residency = 0,
> + .enter = &snooze_loop },
> { /* Shared Cede */
> .name = "Shared Cede",
> .desc = "Shared Cede",
> - .exit_latency = 0,
> - .target_residency = 0,
> + .exit_latency = 10,
> + .target_residency = 100,
> .enter = &shared_cede_loop },
> };
>
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