From 5ddcc03a07ae1ab5062f89a946d9495f1fd8eaa4 Mon Sep 17 00:00:00 2001 From: Aboorva Devarajan Date: Mon, 14 Nov 2022 20:26:11 +0530 Subject: powerpc/cpuidle: Set CPUIDLE_FLAG_POLLING for snooze state During the comparative study of cpuidle governors, it is noticed that the menu governor does not select CEDE state in some scenarios even though when the sleep duration of the CPU exceeds the target residency of the CEDE idle state this is because the CPU exits the snooze "polling" state when snooze time limit is reached in the snooze_loop(), which is not a real wake up and it just means that the polling state selection was not adequate. cpuidle governors rely on CPUIDLE_FLAG_POLLING flag to be set for the polling states to handle the condition mentioned above. Hence, set the CPUIDLE_FLAG_POLLING flag for snooze state (polling state) in powerpc arch to make the cpuidle governor work as expected. Reference Commits: - Timeout enabled for snooze state: commit 78eaa10f027c ("cpuidle: powernv/pseries: Auto-promotion of snooze to deeper idle state") - commit dc2251bf98c6 ("cpuidle: Eliminate the CPUIDLE_DRIVER_STATE_START symbol") - Fix wakeup stats in governor for polling states commit 5f26bdceb9c0 ("cpuidle: menu: Fix wakeup statistics updates for polling state") Signed-off-by: Aboorva Devarajan Tested-by: Vishal Chourasia Reviewed-by: Vaidyanathan Srinivasan Reviewed-by: Vishal Chourasia Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221114145611.37669-1-aboorvad@linux.vnet.ibm.com --- drivers/cpuidle/cpuidle-powernv.c | 5 ++++- drivers/cpuidle/cpuidle-pseries.c | 8 ++++++-- 2 files changed, 10 insertions(+), 3 deletions(-) (limited to 'drivers/cpuidle') diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c index 0b5461b3d7dd..9ebedd972df0 100644 --- a/drivers/cpuidle/cpuidle-powernv.c +++ b/drivers/cpuidle/cpuidle-powernv.c @@ -76,6 +76,7 @@ static int snooze_loop(struct cpuidle_device *dev, local_irq_enable(); snooze_exit_time = get_tb() + get_snooze_timeout(dev, drv, index); + dev->poll_time_limit = false; ppc64_runlatch_off(); HMT_very_low(); while (!need_resched()) { @@ -86,6 +87,7 @@ static int snooze_loop(struct cpuidle_device *dev, * cleared to order subsequent test of need_resched(). */ clear_thread_flag(TIF_POLLING_NRFLAG); + dev->poll_time_limit = true; smp_mb(); break; } @@ -155,7 +157,8 @@ static struct cpuidle_state powernv_states[CPUIDLE_STATE_MAX] = { .desc = "snooze", .exit_latency = 0, .target_residency = 0, - .enter = snooze_loop }, + .enter = snooze_loop, + .flags = CPUIDLE_FLAG_POLLING }, }; static int powernv_cpuidle_cpu_online(unsigned int cpu) diff --git a/drivers/cpuidle/cpuidle-pseries.c b/drivers/cpuidle/cpuidle-pseries.c index 7e7ab5597d7a..1bad4d2b7be3 100644 --- a/drivers/cpuidle/cpuidle-pseries.c +++ b/drivers/cpuidle/cpuidle-pseries.c @@ -44,6 +44,7 @@ static int snooze_loop(struct cpuidle_device *dev, pseries_idle_prolog(); local_irq_enable(); snooze_exit_time = get_tb() + snooze_timeout; + dev->poll_time_limit = false; while (!need_resched()) { HMT_low(); @@ -54,6 +55,7 @@ static int snooze_loop(struct cpuidle_device *dev, * loop anyway. Require a barrier after polling is * cleared to order subsequent test of need_resched(). */ + dev->poll_time_limit = true; clear_thread_flag(TIF_POLLING_NRFLAG); smp_mb(); break; @@ -268,7 +270,8 @@ static struct cpuidle_state dedicated_states[NR_DEDICATED_STATES] = { .desc = "snooze", .exit_latency = 0, .target_residency = 0, - .enter = &snooze_loop }, + .enter = &snooze_loop, + .flags = CPUIDLE_FLAG_POLLING }, { /* CEDE */ .name = "CEDE", .desc = "CEDE", @@ -286,7 +289,8 @@ static struct cpuidle_state shared_states[] = { .desc = "snooze", .exit_latency = 0, .target_residency = 0, - .enter = &snooze_loop }, + .enter = &snooze_loop, + .flags = CPUIDLE_FLAG_POLLING }, { /* Shared Cede */ .name = "Shared Cede", .desc = "Shared Cede", -- cgit v1.2.3