From: Beata Michalska <beata.michalska@arm.com>
To: Sumit Gupta <sumitg@nvidia.com>
Cc: Ionela Voinescu <ionela.voinescu@arm.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
vanshikonda@os.amperecomputing.com, sudeep.holla@arm.com,
will@kernel.org, catalin.marinas@arm.com,
vincent.guittot@linaro.org, yang@os.amperecomputing.com,
lihuisong@huawei.com, linux-tegra <linux-tegra@vger.kernel.org>
Subject: Re: [PATCH v3 0/3] Add support for AArch64 AMUv1-based arch_freq_get_on_cpu
Date: Wed, 3 Apr 2024 23:30:33 +0200 [thread overview]
Message-ID: <Zg3KeYoIozB01fJp@arm.com> (raw)
In-Reply-To: <21a78951-2d4a-1d6e-0cd8-6a4a75ccb142@nvidia.com>
On Wed, Mar 20, 2024 at 10:22:22PM +0530, Sumit Gupta wrote:
> Hi Beata,
>
> > > On Tuesday 12 Mar 2024 at 08:34:28 (+0000), Beata Michalska wrote:
> > > > Introducing arm64 specific version of arch_freq_get_on_cpu, cashing on
> > > > existing implementation for FIE and AMUv1 support: the frequency scale
> > > > factor, updated on each sched tick, serves as a base for retrieving
> > > > the frequency for a given CPU, representing an average frequency
> > > > reported between the ticks - thus its accuracy is limited.
> > > >
> > > > The changes have been rather lightly (due to some limitations) tested on
> > > > an FVP model.
> > > >
> > > > Relevant discussions:
> > > > [1] https://lore.kernel.org/all/20240229162520.970986-1-vanshikonda@os.amperecomputing.com/
> > > > [2] https://lore.kernel.org/all/7eozim2xnepacnnkzxlbx34hib4otycnbn4dqymfziqou5lw5u@5xzpv3t7sxo3/
> > > > [3] https://lore.kernel.org/all/20231212072617.14756-1-lihuisong@huawei.com/
> > > > [4] https://lore.kernel.org/lkml/ZIHpd6unkOtYVEqP@e120325.cambridge.arm.com/T/#m4e74cb5a0aaa353c60fedc6cfb95ab7a6e381e3c
> > > >
> > > > v3:
> > > > - dropping changes to cpufreq_verify_current_freq
> > > > - pulling in changes from Ionela initializing capacity_freq_ref to 0
> > > > (thanks for that!) and applying suggestions made by her during last review:
> > > > - switching to arch_scale_freq_capacity and arch_scale_freq_ref when
> > > > reversing freq scale factor computation
> > > > - swapping shift with multiplication
> > > > - adding time limit for considering last scale update as valid
> > > > - updating frequency scale factor upon entering idle
> > > >
> > > > v2:
> > > > - Splitting the patches
> > > > - Adding comment for full dyntick mode
> > > > - Plugging arch_freq_get_on_cpu into cpufreq_verify_current_freq instead
> > > > of in show_cpuinfo_cur_freq to allow the framework to stay more in sync
> > > > with potential freq changes
> > > >
> > > > Beata Michalska (2):
> > > > arm64: Provide an AMU-based version of arch_freq_get_on_cpu
> > > > arm64: Update AMU-based frequency scale factor on entering idle
> > > >
> > > > Ionela Voinescu (1):
> > > > arch_topology: init capacity_freq_ref to 0
> > > >
> > >
> > > Should there have been a patch that adds a call to
> > > arch_freq_get_on_cpu() from show_cpuinfo_cur_freq() as well?
> > >
> > > My understanding from this [1] thread and others referenced there is
> > > that was something we wanted.
> > >
> > Right, so I must have missunderstood that, as the way I did read it was that
> > it is acceptable to keep things as they are wrt cpufreq sysfs entries.
> >
> > ---
> > BR
> > Beata
> > > [1] https://lore.kernel.org/lkml/2cfbc633-1e94-d741-2337-e1b0cf48b81b@nvidia.com/
> > >
> > > Thanks,
> > > Ionela.
> > >
>
> Yes, the change to show_cpuinfo_cur_freq from [1] is needed.
>
Noted. Will send an update including fixes and this requested change.
---
BR
Beata
> [1]
> https://lore.kernel.org/lkml/20230606155754.245998-1-beata.michalska@arm.com/
>
> Thank you,
> Sumit Gupta
prev parent reply other threads:[~2024-04-03 21:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240312083431.3239989-1-beata.michalska@arm.com>
[not found] ` <20240312083431.3239989-3-beata.michalska@arm.com>
2024-03-20 16:43 ` [PATCH v3 2/3] arm64: Provide an AMU-based version of arch_freq_get_on_cpu Sumit Gupta
2024-04-03 21:28 ` Beata Michalska
[not found] ` <ZfGbyfBl35cyACAc@arm.com>
[not found] ` <ZfI7pQtXgXAG7RBH@arm.com>
2024-03-20 16:52 ` [PATCH v3 0/3] Add support for AArch64 AMUv1-based arch_freq_get_on_cpu Sumit Gupta
2024-04-03 21:30 ` Beata Michalska [this message]
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