From: Mihai Carabas <mihai.carabas@oracle.com> To: linux-arm-kernel@lists.infradead.org Cc: kvm@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, pbonzini@redhat.com, wanpengli@tencent.com, vkuznets@redhat.com, rafael@kernel.org, daniel.lezcano@linaro.org, akpm@linux-foundation.org, pmladek@suse.com, peterz@infradead.org, dianders@chromium.org, npiggin@gmail.com, rick.p.edgecombe@intel.com, joao.m.martins@oracle.com, juerg.haefliger@canonical.com, mic@digikod.net, mihai.carabas@oracle.com, arnd@arndb.de, ankur.a.arora@oracle.com Subject: [PATCH v4 7/8] cpuidle/poll_state: replace cpu_relax with smp_cond_load_relaxed Date: Thu, 15 Feb 2024 09:41:49 +0200 [thread overview] Message-ID: <1707982910-27680-8-git-send-email-mihai.carabas@oracle.com> (raw) In-Reply-To: <1707982910-27680-1-git-send-email-mihai.carabas@oracle.com> 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@infradead.org> Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com> --- drivers/cpuidle/poll_state.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/drivers/cpuidle/poll_state.c b/drivers/cpuidle/poll_state.c index 9b6d90a72601..1e45be906e72 100644 --- a/drivers/cpuidle/poll_state.c +++ b/drivers/cpuidle/poll_state.c @@ -13,6 +13,7 @@ static int __cpuidle poll_idle(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { + unsigned long ret; u64 time_start; time_start = local_clock_noinstr(); @@ -26,12 +27,16 @@ 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; + + ret = smp_cond_load_relaxed(¤t_thread_info()->flags, + VAL & _TIF_NEED_RESCHED || + loop_count++ >= POLL_IDLE_RELAX_COUNT); + + if (!(ret & _TIF_NEED_RESCHED)) + break; + if (local_clock_noinstr() - time_start > limit) { dev->poll_time_limit = true; break; -- 1.8.3.1
WARNING: multiple messages have this Message-ID (diff)
From: Mihai Carabas <mihai.carabas@oracle.com> To: linux-arm-kernel@lists.infradead.org Cc: kvm@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, pbonzini@redhat.com, wanpengli@tencent.com, vkuznets@redhat.com, rafael@kernel.org, daniel.lezcano@linaro.org, akpm@linux-foundation.org, pmladek@suse.com, peterz@infradead.org, dianders@chromium.org, npiggin@gmail.com, rick.p.edgecombe@intel.com, joao.m.martins@oracle.com, juerg.haefliger@canonical.com, mic@digikod.net, mihai.carabas@oracle.com, arnd@arndb.de, ankur.a.arora@oracle.com Subject: [PATCH v4 7/8] cpuidle/poll_state: replace cpu_relax with smp_cond_load_relaxed Date: Thu, 15 Feb 2024 09:41:49 +0200 [thread overview] Message-ID: <1707982910-27680-8-git-send-email-mihai.carabas@oracle.com> (raw) In-Reply-To: <1707982910-27680-1-git-send-email-mihai.carabas@oracle.com> 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@infradead.org> Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com> --- drivers/cpuidle/poll_state.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/drivers/cpuidle/poll_state.c b/drivers/cpuidle/poll_state.c index 9b6d90a72601..1e45be906e72 100644 --- a/drivers/cpuidle/poll_state.c +++ b/drivers/cpuidle/poll_state.c @@ -13,6 +13,7 @@ static int __cpuidle poll_idle(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { + unsigned long ret; u64 time_start; time_start = local_clock_noinstr(); @@ -26,12 +27,16 @@ 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; + + ret = smp_cond_load_relaxed(¤t_thread_info()->flags, + VAL & _TIF_NEED_RESCHED || + loop_count++ >= POLL_IDLE_RELAX_COUNT); + + if (!(ret & _TIF_NEED_RESCHED)) + break; + if (local_clock_noinstr() - time_start > limit) { dev->poll_time_limit = true; break; -- 1.8.3.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2024-02-15 8:58 UTC|newest] Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-02-15 7:41 [PATCH v4] Enable haltpoll for arm64 Mihai Carabas 2024-02-15 7:41 ` Mihai Carabas 2024-02-15 7:41 ` [PATCH v4 1/8] x86: Move ARCH_HAS_CPU_RELAX to arch Mihai Carabas 2024-02-15 7:41 ` Mihai Carabas 2024-02-15 7:41 ` [PATCH v4 2/8] x86/kvm: Move haltpoll_want() to be arch defined Mihai Carabas 2024-02-15 7:41 ` Mihai Carabas 2024-02-15 7:41 ` [PATCH v4 3/8] governors/haltpoll: Drop kvm_para_available() check Mihai Carabas 2024-02-15 7:41 ` Mihai Carabas 2024-02-15 7:41 ` [PATCH v4 4/8] arm64: Select ARCH_HAS_CPU_RELAX Mihai Carabas 2024-02-15 7:41 ` Mihai Carabas 2024-02-15 7:41 ` [PATCH v4 5/8] arm64: Define TIF_POLLING_NRFLAG Mihai Carabas 2024-02-15 7:41 ` Mihai Carabas 2024-02-15 7:41 ` [PATCH v4 6/8] cpuidle-haltpoll: ARM64 support Mihai Carabas 2024-02-15 7:41 ` Mihai Carabas 2024-02-26 8:30 ` Tomohiro Misono (Fujitsu) 2024-02-26 8:30 ` Tomohiro Misono (Fujitsu) 2024-02-15 7:41 ` Mihai Carabas [this message] 2024-02-15 7:41 ` [PATCH v4 7/8] cpuidle/poll_state: replace cpu_relax with smp_cond_load_relaxed Mihai Carabas 2024-02-26 8:36 ` Tomohiro Misono (Fujitsu) 2024-02-26 8:36 ` Tomohiro Misono (Fujitsu) 2024-02-28 4:36 ` Ankur Arora 2024-02-28 4:36 ` Ankur Arora 2024-04-05 21:51 ` Okanovic, Haris 2024-04-05 21:51 ` Okanovic, Haris 2024-04-05 23:14 ` Ankur Arora 2024-04-05 23:14 ` Ankur Arora 2024-04-06 18:42 ` Okanovic, Haris 2024-04-06 18:42 ` Okanovic, Haris 2024-04-08 18:46 ` Ankur Arora 2024-04-08 18:46 ` Ankur Arora 2024-04-08 20:04 ` Okanovic, Haris 2024-04-08 20:04 ` Okanovic, Haris 2024-02-15 7:41 ` [PATCH v4 8/8] cpuidle: replace with HAS_CPU_RELAX with HAS_WANTS_IDLE_POLL Mihai Carabas 2024-02-15 7:41 ` Mihai Carabas
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