From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Linux PM <linux-pm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Lukasz Luba <lukasz.luba@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
Pierre Gondois <pierre.gondois@arm.com>,
Christian Loehle <christian.loehle@arm.com>,
Tim Chen <tim.c.chen@linux.intel.com>
Subject: Re: [RFT][PATCH v1 7/8] cpufreq: intel_pstate: Align perf domains with L2 cache
Date: Thu, 1 May 2025 14:30:32 +0200 [thread overview]
Message-ID: <c8ea80f0-66ee-4c13-ae52-eefab161faf4@arm.com> (raw)
In-Reply-To: <CAJZ5v0g+pRw4H39-BNKKD9KhtRm78y9Q9a3K+yjjK1jskcbJnw@mail.gmail.com>
On 30/04/2025 21:29, Rafael J. Wysocki wrote:
> On Sun, Apr 27, 2025 at 6:23 PM Dietmar Eggemann
> <dietmar.eggemann@arm.com> wrote:
>>
>> On 16/04/2025 20:10, Rafael J. Wysocki wrote:
>>> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
[...]
>> There seems to be an issue with late CPU-hotplug-in and this alignment
>> on L2 cache boundaries.
[...]
> I see.
>
> What happens is that cpu_cacheinfo hides information on offline CPUs,
> so when CPU20 goes online, it doesn't see any other CPUs sharing the
> L2 with it. Accordingly, a PD is created just for itself.
>
> When CPU21 goes online, it sees that CPU20 shares the L2 with it, so
> the code attempts to create a PD for them both which fails.
>
> This could be addressed, but the code would need to be a bit more
> complex and the current hardware seems to do better with a PD per CPU,
> so I'll drop the $subject patch for now.
Ah OK, thanks!
next prev parent reply other threads:[~2025-05-01 12:30 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-16 17:44 [RFT][PATCH v1 0/8] cpufreq: intel_pstate: Enable EAS on hybrid platforms without SMT Rafael J. Wysocki
2025-04-16 17:48 ` [RFT][PATCH v1 1/8] cpufreq/sched: schedutil: Add helper for governor checks Rafael J. Wysocki
2025-04-17 12:23 ` Christian Loehle
2025-04-16 17:59 ` [RFT][PATCH v1 2/8] cpufreq/sched: Move cpufreq-specific EAS checks to cpufreq Rafael J. Wysocki
2025-04-17 12:28 ` Christian Loehle
2025-04-16 18:01 ` [RFT][PATCH v1 3/8] cpufreq/sched: Allow .setpolicy() cpufreq drivers to enable EAS Rafael J. Wysocki
2025-04-17 12:19 ` Christian Loehle
2025-04-17 13:01 ` Rafael J. Wysocki
2025-04-17 13:03 ` Christian Loehle
2025-04-16 18:04 ` [RFT][PATCH v1 4/8] PM: EM: Move CPU capacity check to em_adjust_new_capacity() Rafael J. Wysocki
2025-04-16 18:06 ` [RFT][PATCH v1 5/8] PM: EM: Introduce em_adjust_cpu_capacity() Rafael J. Wysocki
2025-04-27 14:01 ` Dietmar Eggemann
2025-04-30 19:23 ` Rafael J. Wysocki
2025-05-01 12:30 ` Dietmar Eggemann
2025-05-06 19:46 ` Rafael J. Wysocki
2025-04-16 18:09 ` [RFT][PATCH v1 6/8] cpufreq: intel_pstate: EAS support for hybrid platforms Rafael J. Wysocki
2025-04-16 18:10 ` [RFT][PATCH v1 7/8] cpufreq: intel_pstate: Align perf domains with L2 cache Rafael J. Wysocki
2025-04-17 12:42 ` Christian Loehle
2025-04-27 16:23 ` Dietmar Eggemann
2025-04-30 19:29 ` Rafael J. Wysocki
2025-05-01 12:30 ` Dietmar Eggemann [this message]
2025-04-16 18:12 ` [RFT][PATCH v1 8/8] cpufreq: intel_pstate: EAS: Increase cost for CPUs using L3 cache Rafael J. Wysocki
2025-04-25 21:32 ` Christian Loehle
2025-04-25 21:39 ` Rafael J. Wysocki
2025-04-18 9:58 ` [RFT][PATCH v1 0/8] cpufreq: intel_pstate: Enable EAS on hybrid platforms without SMT Christian Loehle
2025-04-18 19:52 ` Rafael J. Wysocki
2025-05-12 13:23 ` [PATCH v1] cpufreq: Drop policy locking from cpufreq_policy_is_good_for_eas() Rafael J. Wysocki
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