From: Beata Michalska <beata.michalska@arm.com> To: Ionela Voinescu <ionela.voinescu@arm.com> Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, sumitg@nvidia.com, sudeep.holla@arm.covm, will@kernel.org, catalin.marinas@arm.com, viresh.kumar@linaro.org, rafael@kernel.org, yang@os.amperecomputing.com, linux-tegra@vger.kernel.org Subject: Re: [PATCH v2 2/2] cpufreq: Wire-up arch-flavored freq info into cpufreq_verify_current_freq Date: Fri, 2 Feb 2024 10:14:47 +0100 [thread overview] Message-ID: <ZbyyhxYACe07vocu@e129154.nice.arm.com> (raw) In-Reply-To: <ZWXy0h/fFfQh+Rhy@arm.com> Hi Ionela, So sorry for relpying so late, lost if from my rader for a while ... On Tue, Nov 28, 2023 at 02:01:54PM +0000, Ionela Voinescu wrote: > Hi Beata, Sumit, > > On Monday 27 Nov 2023 at 16:08:38 (+0000), Beata Michalska wrote: > > From: Sumit Gupta <sumitg@nvidia.com> > > > > When available, use arch_freq_get_on_cpu to obtain current frequency > > (usually an average reported over given period of time) > > to better align the cpufreq's view on the current state of affairs. > > This also automatically pulls in the update for cpuinfo_cur_freq sysfs > > attribute, aligning it with the scaling_cur_freq one, and thus providing > > consistent view on relevant platforms. > > > > Signed-off-by: Sumit Gupta <sumitg@nvidia.com> > > [BM: Subject & commit msg] > > Signed-off-by: Beata Michalska <beata.michalska@arm.com> > > --- > > drivers/cpufreq/cpufreq.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > > index 8c4f9c2f9c44..109559438f45 100644 > > --- a/drivers/cpufreq/cpufreq.c > > +++ b/drivers/cpufreq/cpufreq.c > > @@ -1756,7 +1756,8 @@ static unsigned int cpufreq_verify_current_freq(struct cpufreq_policy *policy, b > > { > > unsigned int new_freq; > > > > - new_freq = cpufreq_driver->get(policy->cpu); > > + new_freq = arch_freq_get_on_cpu(policy->cpu); > > + new_freq = new_freq ?: cpufreq_driver->get(policy->cpu); > > Given that arch_freq_get_on_cpu() is an average frequency, it does not > seem right to me to trigger the sync & update process of > cpufreq_verify_current_freq() based on it. > > cpufreq_verify_current_freq() will at least modify the internal state of > the policy and send PRE and POST notifications, if not do a full frequency > update, based on this average frequency, which is likely different from > the current frequency, even beyond the 1MHz threshold. > Noted, will drop this change. --- BR Beata > While I believe it's okay to return this average frequency in > cpuinfo_cur_freq, I don't think it should be used as an indication of > an accurate current frequency, which is what > cpufreq_verify_current_freq() expects. > > Sumit, can you give more details on the issue at [1] and why this change > fixes it? > > [1] https://lore.kernel.org/lkml/6a5710f6-bfbb-5dfd-11cd-0cd02220cee7@nvidia.com/ > > Thank you, > Ionela. > > > if (!new_freq) > > return 0; > > > > -- > > 2.25.1 > >
WARNING: multiple messages have this Message-ID (diff)
From: Beata Michalska <beata.michalska@arm.com> To: Ionela Voinescu <ionela.voinescu@arm.com> Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, sumitg@nvidia.com, sudeep.holla@arm.covm, will@kernel.org, catalin.marinas@arm.com, viresh.kumar@linaro.org, rafael@kernel.org, yang@os.amperecomputing.com, linux-tegra@vger.kernel.org Subject: Re: [PATCH v2 2/2] cpufreq: Wire-up arch-flavored freq info into cpufreq_verify_current_freq Date: Fri, 2 Feb 2024 10:14:47 +0100 [thread overview] Message-ID: <ZbyyhxYACe07vocu@e129154.nice.arm.com> (raw) In-Reply-To: <ZWXy0h/fFfQh+Rhy@arm.com> Hi Ionela, So sorry for relpying so late, lost if from my rader for a while ... On Tue, Nov 28, 2023 at 02:01:54PM +0000, Ionela Voinescu wrote: > Hi Beata, Sumit, > > On Monday 27 Nov 2023 at 16:08:38 (+0000), Beata Michalska wrote: > > From: Sumit Gupta <sumitg@nvidia.com> > > > > When available, use arch_freq_get_on_cpu to obtain current frequency > > (usually an average reported over given period of time) > > to better align the cpufreq's view on the current state of affairs. > > This also automatically pulls in the update for cpuinfo_cur_freq sysfs > > attribute, aligning it with the scaling_cur_freq one, and thus providing > > consistent view on relevant platforms. > > > > Signed-off-by: Sumit Gupta <sumitg@nvidia.com> > > [BM: Subject & commit msg] > > Signed-off-by: Beata Michalska <beata.michalska@arm.com> > > --- > > drivers/cpufreq/cpufreq.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > > index 8c4f9c2f9c44..109559438f45 100644 > > --- a/drivers/cpufreq/cpufreq.c > > +++ b/drivers/cpufreq/cpufreq.c > > @@ -1756,7 +1756,8 @@ static unsigned int cpufreq_verify_current_freq(struct cpufreq_policy *policy, b > > { > > unsigned int new_freq; > > > > - new_freq = cpufreq_driver->get(policy->cpu); > > + new_freq = arch_freq_get_on_cpu(policy->cpu); > > + new_freq = new_freq ?: cpufreq_driver->get(policy->cpu); > > Given that arch_freq_get_on_cpu() is an average frequency, it does not > seem right to me to trigger the sync & update process of > cpufreq_verify_current_freq() based on it. > > cpufreq_verify_current_freq() will at least modify the internal state of > the policy and send PRE and POST notifications, if not do a full frequency > update, based on this average frequency, which is likely different from > the current frequency, even beyond the 1MHz threshold. > Noted, will drop this change. --- BR Beata > While I believe it's okay to return this average frequency in > cpuinfo_cur_freq, I don't think it should be used as an indication of > an accurate current frequency, which is what > cpufreq_verify_current_freq() expects. > > Sumit, can you give more details on the issue at [1] and why this change > fixes it? > > [1] https://lore.kernel.org/lkml/6a5710f6-bfbb-5dfd-11cd-0cd02220cee7@nvidia.com/ > > Thank you, > Ionela. > > > if (!new_freq) > > return 0; > > > > -- > > 2.25.1 > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2024-02-02 9:15 UTC|newest] Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-11-27 16:08 [PATCH v2 0/2] Add support for AArch64 AMUv1-based arch_freq_get_on_cpu Beata Michalska 2023-11-27 16:08 ` Beata Michalska 2023-11-27 16:08 ` [PATCH v2 1/2] arm64: Provide an AMU-based version of arch_freq_get_on_cpu Beata Michalska 2023-11-27 16:08 ` Beata Michalska 2023-11-28 15:13 ` Ionela Voinescu 2023-11-28 15:13 ` Ionela Voinescu 2024-02-02 9:20 ` Beata Michalska 2024-02-02 9:20 ` Beata Michalska 2024-02-22 19:55 ` Vanshidhar Konda 2024-02-22 19:55 ` Vanshidhar Konda 2023-11-27 16:08 ` [PATCH v2 2/2] cpufreq: Wire-up arch-flavored freq info into cpufreq_verify_current_freq Beata Michalska 2023-11-27 16:08 ` Beata Michalska 2023-11-28 14:01 ` Ionela Voinescu 2023-11-28 14:01 ` Ionela Voinescu 2023-12-01 13:02 ` Sumit Gupta 2023-12-01 13:02 ` Sumit Gupta 2023-12-05 11:05 ` Ionela Voinescu 2023-12-05 11:05 ` Ionela Voinescu 2023-12-06 13:28 ` Sumit Gupta 2023-12-06 13:28 ` Sumit Gupta 2023-12-07 9:22 ` Ionela Voinescu 2023-12-07 9:22 ` Ionela Voinescu 2023-12-08 15:34 ` Sumit Gupta 2023-12-08 15:34 ` Sumit Gupta 2024-02-02 9:14 ` Beata Michalska [this message] 2024-02-02 9:14 ` Beata Michalska 2023-12-06 20:41 ` Rafael J. Wysocki 2023-12-06 20:41 ` Rafael J. Wysocki 2024-02-02 9:05 ` Beata Michalska 2024-02-02 9:05 ` Beata Michalska
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