From: Mason <slash.tmp@free.fr> To: Viresh Kumar <viresh.kumar@linaro.org> Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>, 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: Thu, 14 May 2015 16:48:33 +0200 [thread overview] Message-ID: <5554B5C1.2070402@free.fr> (raw) In-Reply-To: <CAKohpon4AV-7nq=Qm7PpDbbW9ti98avY9zz82htzyHWi5_K7fA@mail.gmail.com> On 14/05/2015 15:59, Viresh Kumar wrote: > On 14 May 2015 at 18:36, Mason wrote: >> When I execute "echo 18500 > scaling_max_freq" >> the system is supposed to change the CPU frequency to 18.5 MHz >> (I might have a bug lurking there) and PERIPHCLK is 1/2 of that, >> i.e 9.25 MHz. > > So at least we are on the right path. But it looks to me that this > call is not getting propagated well. > > From the attachment you gave initially, the event handler for > twd-timers is: tick_handle_periodic(). i.e. you are running in > periodic mode and not one-shot... why ? I don't know. Is it not obvious (to someone who knows what to look for) from reading the smp_twd.c source? How do I run the TWD in one-shot mode? >> Yes, I do, but I was trying to use as much generic code as >> possible to limit the chances of introducing bugs. > > Hmm.. > >> I'll take a fresh look at the ARM GLOBAL TIMER, but last I >> checked, it didn't seem to handle frequency scaling. > > why is that required? Why will you change its freq ? http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0407g/CIHGECHJ.html "The global timer is clocked by PERIPHCLK." PERIPHCLK = CPUCLK/2 Change the CPUCLK, change the PERIPHCLK. > The same timer is probably used for SPEAr (the platform > I used to work on): > > http://lxr.free-electrons.com/source/arch/arm/mach-spear/time.c?v=3.14 Did that platform use cpufreq DFS? Regards.
WARNING: multiple messages have this Message-ID (diff)
From: slash.tmp@free.fr (Mason) To: linux-arm-kernel@lists.infradead.org Subject: schedule_timeout sleeps too long after dividing CPU frequency Date: Thu, 14 May 2015 16:48:33 +0200 [thread overview] Message-ID: <5554B5C1.2070402@free.fr> (raw) In-Reply-To: <CAKohpon4AV-7nq=Qm7PpDbbW9ti98avY9zz82htzyHWi5_K7fA@mail.gmail.com> On 14/05/2015 15:59, Viresh Kumar wrote: > On 14 May 2015 at 18:36, Mason wrote: >> When I execute "echo 18500 > scaling_max_freq" >> the system is supposed to change the CPU frequency to 18.5 MHz >> (I might have a bug lurking there) and PERIPHCLK is 1/2 of that, >> i.e 9.25 MHz. > > So at least we are on the right path. But it looks to me that this > call is not getting propagated well. > > From the attachment you gave initially, the event handler for > twd-timers is: tick_handle_periodic(). i.e. you are running in > periodic mode and not one-shot... why ? I don't know. Is it not obvious (to someone who knows what to look for) from reading the smp_twd.c source? How do I run the TWD in one-shot mode? >> Yes, I do, but I was trying to use as much generic code as >> possible to limit the chances of introducing bugs. > > Hmm.. > >> I'll take a fresh look at the ARM GLOBAL TIMER, but last I >> checked, it didn't seem to handle frequency scaling. > > why is that required? Why will you change its freq ? http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0407g/CIHGECHJ.html "The global timer is clocked by PERIPHCLK." PERIPHCLK = CPUCLK/2 Change the CPUCLK, change the PERIPHCLK. > The same timer is probably used for SPEAr (the platform > I used to work on): > > http://lxr.free-electrons.com/source/arch/arm/mach-spear/time.c?v=3.14 Did that platform use cpufreq DFS? Regards.
next prev parent reply other threads:[~2015-05-14 14:48 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 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 [this message] 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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