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 10:51:59 +0100 [thread overview] Message-ID: <20150515095159.GF2067@n2100.arm.linux.org.uk> (raw) In-Reply-To: <5555BC7E.7010601@free.fr> On Fri, May 15, 2015 at 11:29:34AM +0200, Mason wrote: > On 14/05/2015 16:42, Russell King - ARM Linux wrote: > > > If it's in periodic mode, the update should still be propagated to the > > hardware, assuming the generic time keeping code doesn't produce an > > error. > > > > twd_update_frequency > > `-clockevents_update_freq > > `-__clockevents_update_freq > > `-__clockevents_set_state(, CLOCK_EVT_STATE_PERIODIC) > > `-dev->set_mode (twd_set_mode) > > > > That re-writes the TWD_TIMER_LOAD register based on twd_timer_rate, > > which would have been updated by twd_update_frequency(). > > > > The question I posed earlier remains: is clockevents_update_freq() > > failing? We don't know, because we never check its return value. > > > > Another thing to look at is whether we reach twd_set_mode(). > > > > Lastly, printing the values of the TWD_TIMER_LOAD and TWD_TIMER_COUNTER > > after twd_set_mode() has written TWD_TIMER_LOAD might provide some > > hints as to what's going on. > > I'll have access to the board on Monday. > > I'll add printk in strategic places, and report back ASAP. That would be good. > (I'm considering dropping TWD, and using platform timers.) As you don't say which kernel version you're using, 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 -- 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 10:51:59 +0100 [thread overview] Message-ID: <20150515095159.GF2067@n2100.arm.linux.org.uk> (raw) In-Reply-To: <5555BC7E.7010601@free.fr> On Fri, May 15, 2015 at 11:29:34AM +0200, Mason wrote: > On 14/05/2015 16:42, Russell King - ARM Linux wrote: > > > If it's in periodic mode, the update should still be propagated to the > > hardware, assuming the generic time keeping code doesn't produce an > > error. > > > > twd_update_frequency > > `-clockevents_update_freq > > `-__clockevents_update_freq > > `-__clockevents_set_state(, CLOCK_EVT_STATE_PERIODIC) > > `-dev->set_mode (twd_set_mode) > > > > That re-writes the TWD_TIMER_LOAD register based on twd_timer_rate, > > which would have been updated by twd_update_frequency(). > > > > The question I posed earlier remains: is clockevents_update_freq() > > failing? We don't know, because we never check its return value. > > > > Another thing to look at is whether we reach twd_set_mode(). > > > > Lastly, printing the values of the TWD_TIMER_LOAD and TWD_TIMER_COUNTER > > after twd_set_mode() has written TWD_TIMER_LOAD might provide some > > hints as to what's going on. > > I'll have access to the board on Monday. > > I'll add printk in strategic places, and report back ASAP. That would be good. > (I'm considering dropping TWD, and using platform timers.) As you don't say which kernel version you're using, 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 -- FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net.
next prev parent reply other threads:[~2015-05-15 9:51 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 [this message] 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 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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