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Message-Id: <1706524834-11275-8-git-send-email-mihai.carabas@oracle.com>
Date: Mon, 29 Jan 2024 12:40:34 +0200
From: Mihai Carabas <mihai.carabas@...cle.com>
To: linux-arm-kernel@...ts.infradead.org
Cc: kvm@...r.kernel.org, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org, catalin.marinas@....com, will@...nel.org,
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vkuznets@...hat.com, rafael@...nel.org, daniel.lezcano@...aro.org,
akpm@...ux-foundation.org, pmladek@...e.com, peterz@...radead.org,
dianders@...omium.org, npiggin@...il.com, rick.p.edgecombe@...el.com,
joao.m.martins@...cle.com, juerg.haefliger@...onical.com,
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ankur.a.arora@...cle.com
Subject: [PATCH v3 7/7] cpuidle/poll_state: replace cpu_relax with smp_cond_load_relaxed
cpu_relax on ARM64 does a simple "yield". Thus we replace it with
smp_cond_load_relaxed which basically does a "wfe".
Suggested-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Mihai Carabas <mihai.carabas@...cle.com>
---
drivers/cpuidle/poll_state.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/drivers/cpuidle/poll_state.c b/drivers/cpuidle/poll_state.c
index 9b6d90a72601..440cd713e39a 100644
--- a/drivers/cpuidle/poll_state.c
+++ b/drivers/cpuidle/poll_state.c
@@ -26,12 +26,16 @@ static int __cpuidle poll_idle(struct cpuidle_device *dev,
limit = cpuidle_poll_time(drv, dev);
- while (!need_resched()) {
- cpu_relax();
- if (loop_count++ < POLL_IDLE_RELAX_COUNT)
- continue;
-
+ for (;;) {
loop_count = 0;
+
+ smp_cond_load_relaxed(¤t_thread_info()->flags,
+ (VAL & _TIF_NEED_RESCHED) ||
+ (loop_count++ >= POLL_IDLE_RELAX_COUNT));
+
+ if (loop_count < POLL_IDLE_RELAX_COUNT)
+ break;
+
if (local_clock_noinstr() - time_start > limit) {
dev->poll_time_limit = true;
break;
--
1.8.3.1
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