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Wysocki" To: Linux PM Cc: LKML , Daniel Lezcano , Christian Loehle , Artem Bityutskiy Subject: [PATCH v1 1/4] cpuidle: teo: Add polling flag check to early return path Date: Fri, 10 Jan 2025 13:53:57 +0100 Message-ID: <13679187.uLZWGnKmhe@rjwysocki.net> In-Reply-To: <4953183.GXAFRqVoOG@rjwysocki.net> References: <4953183.GXAFRqVoOG@rjwysocki.net> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CLIENT-IP: 195.136.19.94 X-CLIENT-HOSTNAME: 195.136.19.94 X-VADE-SPAMSTATE: clean X-VADE-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgeefuddrudegkedggeeiucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecujffqoffgrffnpdggtffipffknecuuegrihhlohhuthemucduhedtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefhvfevufffkfgjfhgggfgtsehtufertddttdejnecuhfhrohhmpedftfgrfhgrvghlucflrdcuhgihshhotghkihdfuceorhhjfiesrhhjfiihshhotghkihdrnhgvtheqnecuggftrfgrthhtvghrnhepvdffueeitdfgvddtudegueejtdffteetgeefkeffvdeftddttdeuhfegfedvjefhnecukfhppeduleehrddufeeirdduledrleegnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehinhgvthepudelhedrudefiedrudelrdelgedphhgvlhhopehkrhgvrggthhgvrhdrlhhotggrlhhnvghtpdhmrghilhhfrhhomheprhhjfiesrhhjfiihshhotghkihdrnhgvthdpnhgspghrtghpthhtohephedprhgtphhtthhopehlihhnuhigqdhpmhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehlihhnuhigqdhkvghrnhgvlhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopegurghnihgvlhdrlhgviigtrghnoheslhhinhgrrhhordhorhhgpdhrtghpthhtoheptghhrhhishhtihgrnhdrlhhovghhlhgvsegrrhhmrdgtohhmpdhrtghpthhtoheprghrthgvmhdrsghithihuhhtshhkihihsehlihh X-DCC--Metrics: v370.home.net.pl 1024; Body=5 Fuz1=5 Fuz2=5 From: Rafael J. Wysocki After commit 6da8f9ba5a87 ("cpuidle: teo: Skip tick_nohz_get_sleep_length() call in some cases") the teo governor behaves a bit differently on systems where idle state 0 is a "polling" state (that is, it is not really an idle state, but a loop continuously executed by the CPU). Namely, on such systems it skips the tick_nohz_get_sleep_length() call if the target residency of the current candidate idle state is small enough. However, if state 0 itself was to be returned, it would be returned right away without calling tick_nohz_get_sleep_length() even on systems where it was not a "polling" state until commit 4b20b07ce72f ("cpuidle: teo: Don't count non-existent intercepts") that attempted to fix this problem. Unfortunately, commit 4b20b07ce72f has made the governor always call tick_nohz_get_sleep_length() when about to return state 0 early, even if that state is a "polling" one, which is inconsistent and defeats the purpose of commit 6da8f9ba5a87 in that case. Address this by adding a CPUIDLE_FLAG_POLLING check to the path where state 0 is returned early to prevent tick_nohz_get_sleep_length() from being called if it is a "polling" state. Fixes: 4b20b07ce72f ("cpuidle: teo: Don't count non-existent intercepts") Signed-off-by: Rafael J. Wysocki --- drivers/cpuidle/governors/teo.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/cpuidle/governors/teo.c +++ b/drivers/cpuidle/governors/teo.c @@ -422,7 +422,8 @@ first_suitable_idx = i; } } - if (!idx && prev_intercept_idx) { + if (!idx && prev_intercept_idx && + !(drv->states[0].flags & CPUIDLE_FLAG_POLLING)) { /* * We have to query the sleep length here otherwise we don't * know after wakeup if our guess was correct.