From: Daniel Wagner <daniel.wagner@bmw-carit.de> To: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: <linux-kernel@vger.kernel.org>, Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>, <linux-pm@vger.kernel.org> Subject: Re: [RFC v0 2/9] suspend: Add getter function to report if freezing is active Date: Mon, 7 Sep 2015 10:55:43 +0200 [thread overview] Message-ID: <55ED510F.7090702@bmw-carit.de> (raw) In-Reply-To: <1683655.HLd9k04Slu@vostro.rjw.lan> On 09/05/2015 04:11 AM, Rafael J. Wysocki wrote: > On Friday, September 04, 2015 03:34:55 PM Daniel Wagner wrote: >> Instead encode the FREEZE state via the CPU state we allow the >> interesting subsystems (MCE, microcode) to query the power >> subsystem directly. > > A use case, please. The motivation for this change is to reduce the complexity in the hotplug code. As tried to point out in the cover letter, the FROZEN bits have only a bunch of users after all those years (2007). So it is worth to have all the notifier users to handle the FROZEN state? Don't know if that counts as use case. >> Most notifiers are not interested at all >> in this information so rather have explicit calls to freeze_active() >> instead adding complexity to the rest of the users of the CPU >> notifiers. > > Why does it has anything to do with CPU notifiers? cpu_{down|up} will call the notifiers with the CPU_TASK_FROZEN bit set and so most notifiers are doing switch (actcion ~CPU_TASK_FROZEN) to filter it out because they don't need to handle the system wide ongoing freeze operations. > We don't offline CPUs for suspend-to-idle. Sure. As I said the motivation is to reduce the complexity in the hotplug code. Thanks, Daniel
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From: Daniel Wagner <daniel.wagner@bmw-carit.de> To: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: linux-kernel@vger.kernel.org, Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>, linux-pm@vger.kernel.org Subject: Re: [RFC v0 2/9] suspend: Add getter function to report if freezing is active Date: Mon, 7 Sep 2015 10:55:43 +0200 [thread overview] Message-ID: <55ED510F.7090702@bmw-carit.de> (raw) In-Reply-To: <1683655.HLd9k04Slu@vostro.rjw.lan> On 09/05/2015 04:11 AM, Rafael J. Wysocki wrote: > On Friday, September 04, 2015 03:34:55 PM Daniel Wagner wrote: >> Instead encode the FREEZE state via the CPU state we allow the >> interesting subsystems (MCE, microcode) to query the power >> subsystem directly. > > A use case, please. The motivation for this change is to reduce the complexity in the hotplug code. As tried to point out in the cover letter, the FROZEN bits have only a bunch of users after all those years (2007). So it is worth to have all the notifier users to handle the FROZEN state? Don't know if that counts as use case. >> Most notifiers are not interested at all >> in this information so rather have explicit calls to freeze_active() >> instead adding complexity to the rest of the users of the CPU >> notifiers. > > Why does it has anything to do with CPU notifiers? cpu_{down|up} will call the notifiers with the CPU_TASK_FROZEN bit set and so most notifiers are doing switch (actcion ~CPU_TASK_FROZEN) to filter it out because they don't need to handle the system wide ongoing freeze operations. > We don't offline CPUs for suspend-to-idle. Sure. As I said the motivation is to reduce the complexity in the hotplug code. Thanks, Daniel
next prev parent reply other threads:[~2015-09-07 8:55 UTC|newest] Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-09-04 13:34 [RFC v0 0/9] Remove CPU_*_FROZEN Daniel Wagner 2015-09-04 13:34 ` [RFC v0 1/9] smpboot: Add a separate CPU state when a surviving CPU times out Daniel Wagner 2015-09-04 13:34 ` Daniel Wagner 2015-09-04 13:34 ` [RFC v0 2/9] suspend: Add getter function to report if freezing is active Daniel Wagner 2015-09-05 2:11 ` Rafael J. Wysocki 2015-09-07 8:55 ` Daniel Wagner [this message] 2015-09-07 8:55 ` Daniel Wagner 2015-09-07 13:42 ` Rafael J. Wysocki 2015-09-07 21:44 ` Rafael J. Wysocki 2015-09-08 8:19 ` Daniel Wagner 2015-09-08 8:19 ` Daniel Wagner 2015-09-04 13:34 ` [RFC v0 3/9] x86: Use freeze_active() instead of CPU_*_FROZEN Daniel Wagner 2015-09-04 13:34 ` [RFC v0 4/9] smpboot: Use freeze_active() instead CPU_DEAD_FROZEN state information Daniel Wagner 2015-09-08 8:49 ` Daniel Wagner 2015-09-04 13:34 ` [RFC v0 5/9] sched: Use freeze_active() instead CPU_*_FROZEN " Daniel Wagner 2015-09-04 13:34 ` [RFC v0 6/9] cpu: Restructure FROZEN state handling Daniel Wagner 2015-09-04 13:35 ` [RFC v0 7/9] cpu: Remove unused CPU_*_FROZEN states Daniel Wagner 2015-09-04 13:35 ` [RFC v0 8/9] cpu: Do not set CPU_TASKS_FROZEN anymore Daniel Wagner 2015-09-04 13:35 ` [RFC v0 9/9] doc: Update cpu-hotplug documents on removal of CPU_TASKS_FROZEN Daniel Wagner
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