From: Artem Bityutskiy <dedekind1@gmail.com>
To: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
lenb@kernel.org, rafael@kernel.org, viresh.kumar@linaro.org
Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] cpufreq: intel_pstate: Update EPP for AlderLake mobile
Date: Wed, 29 Dec 2021 12:22:28 +0200 [thread overview]
Message-ID: <2e5cd069996b1abb477eb4e817391db6f9bfa097.camel@gmail.com> (raw)
In-Reply-To: <20211216183305.3152807-1-srinivas.pandruvada@linux.intel.com>
On Thu, 2021-12-16 at 10:33 -0800, Srinivas Pandruvada wrote:
> There is an expectation from users that they can get frequency specified
> by cpufreq/cpuinfo_max_freq when conditions permit. But with AlderLake
> mobile it may not be possible. This is possible that frequency is clipped
> based on the system power-up EPP value. In this case users can update
> cpufreq/energy_performance_preference to some performance oriented EPP to
> limit clipping of frequencies.
>
> To get out of box behavior as the prior generations of CPUs, update EPP
> for AlderLake mobile CPUs on boot. On prior generations of CPUs EPP = 128
> was enough to get maximum frequency, but with AlderLake mobile the
> equivalent EPP is 102. Since EPP is model specific, this is possible that
> they have different meaning on each generation of CPU.
>
> The current EPP string "balance_performance" corresponds to EPP = 128.
> Change the EPP corresponding to "balance_performance" to 102 for only
> AlderLake mobile CPUs and update this on each CPU during boot.
>
> To implement reuse epp_values[] array and update the modified EPP at the
> index for BALANCE_PERFORMANCE. Add a dummy EPP_INDEX_DEFAULT to
> epp_values[] to match indexes in the energy_perf_strings[].
>
> After HWP PM is enabled also update EPP when "balance_performance" is
> redefined for the very first time after the boot on each CPU. On
> subsequent suspend/resume or offline/online the old EPP is restored,
> so no specific action is needed.
>
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
I think this patch alone makes things a bit inconsistent, because the
'x86_energy_perf_policy' does not get adjusted.
Ideally, constants like HWP_EPP_BALANCE_PERFORMANCE should go away from
arch/x86/include/asm/msr-index.h, along with all users.
Artem.
prev parent reply other threads:[~2021-12-29 10:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-16 18:33 [PATCH] cpufreq: intel_pstate: Update EPP for AlderLake mobile Srinivas Pandruvada
2021-12-17 15:45 ` Rafael J. Wysocki
2021-12-29 10:22 ` Artem Bityutskiy [this message]
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