linux-kernel - Re: [PATCH v7 3/4] arm64: Provide an AMU-based version of arch_freq_avg_get_on

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Message-ID: <Zyh-uVSW-0d0r8oB@arm.com>
Date: Mon, 4 Nov 2024 08:58:49 +0100
From: Beata Michalska <beata.michalska@....com>
To: Viresh Kumar <viresh.kumar@...aro.org>
Cc: Vanshidhar Konda <vanshikonda@...amperecomputing.com>,
	Sumit Gupta <sumitg@...dia.com>, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
	ionela.voinescu@....com, sudeep.holla@....com, will@...nel.org,
	catalin.marinas@....com, rafael@...nel.org,
	yang@...amperecomputing.com, lihuisong@...wei.com,
	zhanjie9@...ilicon.com, linux-tegra <linux-tegra@...r.kernel.org>,
	Bibek Basu <bbasu@...dia.com>
Subject: Re: [PATCH v7 3/4] arm64: Provide an AMU-based version of
 arch_freq_avg_get_on_cpu

On Tue, Oct 29, 2024 at 12:23:19PM +0530, Viresh Kumar wrote:
> On 10-10-24, 13:08, Beata Michalska wrote:
> > That is a fair point but I am not entirely convinced using '0' instead makes
> > things any more clearer as this is in no way a valid CPU frequency.
> > As long as we document the expected behaviour keeping the interface well
> > defined,  both options should be fine I guess.
> > 
> > @Viresh: what is your opinion on that one ?
> 
> Failing to get frequency for the CPU shouldn't be represented by 0,
> even if it is confusing for the user.
We still need to decide  whether provide a more descriptive way of informing
about such cases (whether it be 'unknown' or 'idle' ) or to simply return
an appropriate error and leave the userspace with dealing with that.

---
Thanks
Beata
> 
> -- 
> viresh