From: Russell King - ARM Linux <linux@arm.linux.org.uk> To: Mason <slash.tmp@free.fr> Cc: Viresh Kumar <viresh.kumar@linaro.org>, Daniel Lezcano <daniel.lezcano@linaro.org>, "Rafael J. Wysocki" <rjw@rjwysocki.net>, Mans Rullgard <mans@mansr.com>, Linux ARM <linux-arm-kernel@lists.infradead.org>, Linux PM <linux-pm@vger.kernel.org>, cpufreq <cpufreq@vger.kernel.org> Subject: Re: schedule_timeout sleeps too long after dividing CPU frequency Date: Fri, 15 May 2015 12:58:53 +0100 [thread overview] Message-ID: <20150515115852.GJ2067@n2100.arm.linux.org.uk> (raw) In-Reply-To: <5555CC1A.5040604@free.fr> On Fri, May 15, 2015 at 12:36:10PM +0200, Mason wrote: > On 15/05/2015 11:51, Russell King - ARM Linux wrote: > > > As you don't say which kernel version you're using, > > Sorry about that, I thought the patch-generating command > I posted conveyed the information. > > $ git diff v3.14.41 HEAD >tango.patch && xz tango.patch > > I'm using the 3.14.y branch from linux-stable. So you're using a kernel over a year old... > > for all we know, you might be using a version which omits some fixes > > in this area, such as this one which you really must have if your > > timer is operating in period mode: > > > > fe79a9ba1196 clockevents: Adjust timer interval when frequency changes > > Hmmm, according to git log, this patch was accepted during > the 3.14-rc2 merge window. Why didn't it make it for 3.14? No it wasn't: $ git describe --contains fe79a9ba1196 v3.15-rc1~123^2~12 It was merged during the merge window immediately preceding v3.15-rc1. > By any chance, is there a patch that would allow the platform > to get high-resolution timers when using smp_twd? I think you'll have to do the research for that yourself... what I can say is that TWD is capable of one-shot mode, and is capable of running as a high-res timer: Per CPU device: 0 Clock Event Device: local_timer max_delta_ns: 21691754031 min_delta_ns: 1000 mult: 425201762 shift: 31 mode: 3 <== CLOCK_EVT_MODE_ONESHOT next_event: 595603944000000 nsecs set_next_event: twd_set_next_event set_mode: twd_set_mode event_handler: hrtimer_interrupt <== indicates that it's switched to high-res mode retries: 0 -- FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net.
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From: linux@arm.linux.org.uk (Russell King - ARM Linux) To: linux-arm-kernel@lists.infradead.org Subject: schedule_timeout sleeps too long after dividing CPU frequency Date: Fri, 15 May 2015 12:58:53 +0100 [thread overview] Message-ID: <20150515115852.GJ2067@n2100.arm.linux.org.uk> (raw) In-Reply-To: <5555CC1A.5040604@free.fr> On Fri, May 15, 2015 at 12:36:10PM +0200, Mason wrote: > On 15/05/2015 11:51, Russell King - ARM Linux wrote: > > > As you don't say which kernel version you're using, > > Sorry about that, I thought the patch-generating command > I posted conveyed the information. > > $ git diff v3.14.41 HEAD >tango.patch && xz tango.patch > > I'm using the 3.14.y branch from linux-stable. So you're using a kernel over a year old... > > for all we know, you might be using a version which omits some fixes > > in this area, such as this one which you really must have if your > > timer is operating in period mode: > > > > fe79a9ba1196 clockevents: Adjust timer interval when frequency changes > > Hmmm, according to git log, this patch was accepted during > the 3.14-rc2 merge window. Why didn't it make it for 3.14? No it wasn't: $ git describe --contains fe79a9ba1196 v3.15-rc1~123^2~12 It was merged during the merge window immediately preceding v3.15-rc1. > By any chance, is there a patch that would allow the platform > to get high-resolution timers when using smp_twd? I think you'll have to do the research for that yourself... what I can say is that TWD is capable of one-shot mode, and is capable of running as a high-res timer: Per CPU device: 0 Clock Event Device: local_timer max_delta_ns: 21691754031 min_delta_ns: 1000 mult: 425201762 shift: 31 mode: 3 <== CLOCK_EVT_MODE_ONESHOT next_event: 595603944000000 nsecs set_next_event: twd_set_next_event set_mode: twd_set_mode event_handler: hrtimer_interrupt <== indicates that it's switched to high-res mode retries: 0 -- FTTC broadband for 0.8mile line: currently@10.5Mbps down 400kbps up according to speedtest.net.
next prev parent reply other threads:[~2015-05-15 11:58 UTC|newest] Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-05-12 14:32 schedule_timeout sleeps too long after dividing CPU frequency Mason 2015-05-12 14:32 ` Mason 2015-05-12 14:46 ` Viresh Kumar 2015-05-12 14:46 ` Viresh Kumar 2015-05-12 15:14 ` Mason 2015-05-12 15:14 ` Mason 2015-05-12 15:50 ` Russell King - ARM Linux 2015-05-12 15:50 ` Russell King - ARM Linux 2015-05-12 16:14 ` Mason 2015-05-12 16:14 ` Mason 2015-05-13 16:51 ` Mason 2015-05-13 16:51 ` Mason 2015-05-14 2:13 ` Viresh Kumar 2015-05-14 2:13 ` Viresh Kumar 2015-05-14 11:22 ` Mason 2015-05-14 11:22 ` Mason 2015-05-14 11:54 ` Viresh Kumar 2015-05-14 11:54 ` Viresh Kumar 2015-05-14 13:06 ` Mason 2015-05-14 13:06 ` Mason 2015-05-14 13:53 ` Russell King - ARM Linux 2015-05-14 13:53 ` Russell King - ARM Linux 2015-05-14 14:51 ` Mason 2015-05-14 14:51 ` Mason 2015-05-14 13:59 ` Viresh Kumar 2015-05-14 13:59 ` Viresh Kumar 2015-05-14 13:59 ` Viresh Kumar 2015-05-14 14:38 ` Viresh Kumar 2015-05-14 14:38 ` Viresh Kumar 2015-05-14 14:42 ` Russell King - ARM Linux 2015-05-14 14:42 ` Russell King - ARM Linux 2015-05-15 9:29 ` Mason 2015-05-15 9:29 ` Mason 2015-05-15 9:51 ` Russell King - ARM Linux 2015-05-15 9:51 ` Russell King - ARM Linux 2015-05-15 10:01 ` Viresh Kumar 2015-05-15 10:01 ` Viresh Kumar 2015-05-15 10:36 ` Mason 2015-05-15 10:36 ` Mason 2015-05-15 11:58 ` Russell King - ARM Linux [this message] 2015-05-15 11:58 ` Russell King - ARM Linux 2015-05-15 12:45 ` Mason 2015-05-15 12:45 ` Mason 2015-05-15 13:15 ` Russell King - ARM Linux 2015-05-15 13:15 ` Russell King - ARM Linux 2015-05-15 13:58 ` Mason 2015-05-15 18:35 ` Mason 2015-05-18 11:24 ` Mason 2015-05-18 11:54 ` Russell King - ARM Linux 2015-05-20 16:21 ` Mason 2015-05-20 18:50 ` Arnd Bergmann 2015-05-20 19:34 ` Mason 2015-05-20 20:14 ` Russell King - ARM Linux 2015-05-20 20:41 ` Mason 2015-05-20 20:52 ` Arnd Bergmann 2015-05-20 21:56 ` Mason 2015-05-20 22:18 ` Arnd Bergmann 2015-05-21 12:35 ` Mason 2015-05-20 23:14 ` Russell King - ARM Linux 2015-05-21 9:56 ` Mason 2015-05-21 10:20 ` Russell King - ARM Linux 2015-05-14 14:48 ` Mason 2015-05-14 14:48 ` Mason 2015-05-15 4:16 ` Viresh Kumar 2015-05-15 4:16 ` Viresh Kumar 2015-05-15 5:07 ` Viresh Kumar 2015-05-15 5:07 ` Viresh Kumar 2015-05-15 9:00 ` Russell King - ARM Linux 2015-05-15 9:00 ` Russell King - ARM Linux 2015-05-15 9:21 ` Mason 2015-05-15 9:21 ` Mason 2015-05-15 10:11 ` Mason 2015-05-15 10:11 ` Mason 2015-05-12 15:23 ` Russell King - ARM Linux 2015-05-12 15:23 ` Russell King - ARM Linux 2015-05-12 16:03 ` Mason 2015-05-12 16:03 ` Mason
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