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Message-Id: <20230811170049.308866-10-frederic@kernel.org>
Date: Fri, 11 Aug 2023 19:00:48 +0200
From: Frederic Weisbecker <frederic@...nel.org>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Frederic Weisbecker <frederic@...nel.org>,
Len Brown <lenb@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
"Rafael J . Wysocki" <rafael@...nel.org>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Thomas Gleixner <tglx@...utronix.de>,
Anna-Maria Behnsen <anna-maria@...utronix.de>
Subject: [PATCH 09/10] x86: Remove the current_clr_polling() call upon mwait exit
mwait_idle_with_hints() is mostly called from cpuidle which already sets
back TIF_NR_POLLING and fold TIF_NEED_RESCHED if necessary.
The only non-cpuidle caller is power_saving_thread() which acts as an idle
loop and is the only reason why mwait_idle_with_hints() carries a costly
fully ordered atomic operation upon idle exit.
Make this overhead proper to power_saving_thread() instead which already
duplicates quite some cpuidle code.
Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
---
arch/x86/include/asm/mwait.h | 1 -
drivers/acpi/acpi_pad.c | 1 +
2 files changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h
index 920426d691ce..c1be3775b94a 100644
--- a/arch/x86/include/asm/mwait.h
+++ b/arch/x86/include/asm/mwait.h
@@ -134,7 +134,6 @@ static __always_inline void mwait_idle_with_hints(unsigned long eax, unsigned lo
}
}
}
- current_clr_polling();
}
/*
diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c
index 7a453c5ff303..5a44afafe185 100644
--- a/drivers/acpi/acpi_pad.c
+++ b/drivers/acpi/acpi_pad.c
@@ -174,6 +174,7 @@ static int power_saving_thread(void *data)
stop_critical_timings();
mwait_idle_with_hints(power_saving_mwait_eax, 1);
+ current_clr_polling();
start_critical_timings();
tick_broadcast_exit();
--
2.34.1
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