From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
To: Hillf Danton <hdanton@sina.com>
Cc: Andy Gross <agross@kernel.org>,
Bjorn Andersson <andersson@kernel.org>,
Konrad Dybcio <konrad.dybcio@linaro.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
linux-arm-msm@vger.kernel.org, linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org,
Adrien Thierry <athierry@redhat.com>,
Brian Masney <bmasney@redhat.com>,
linux-rt-users@vger.kernel.org
Subject: Re: [RFC PATCH] cpufreq: qcom-cpufreq-hw: allow work to be done on other CPU for PREEMPT_RT
Date: Fri, 17 Mar 2023 09:13:42 +0100 [thread overview]
Message-ID: <a0e1b3b9-b333-e0ac-ac46-c15a01b356e6@linaro.org> (raw)
In-Reply-To: <20230316235705.2235-1-hdanton@sina.com>
On 17/03/2023 00:57, Hillf Danton wrote:
> On 16 Mar 2023 13:28:18 +0100 Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>> On 15/03/2023 17:49, Krzysztof Kozlowski wrote:
>>> Qualcomm cpufreq driver configures interrupts with affinity to each
>>> cluster, e.g. dcvsh-irq-0, dcvsh-irq-4 and dcvsh-irq-7 on SM8250.
>>> Triggered interrupt will schedule delayed work, but, since workqueue
>>> prefers local CPUs, it might get executed on a CPU dedicated to realtime
>>> tasks causing unexpected latencies in realtime workload.
>>>
>>> Use unbound workqueue for such case. This might come with performance
>>> or energy penalty, e.g. because of cache miss or when other CPU is
>>> sleeping.
>>>
>>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>> ---
>>> drivers/cpufreq/qcom-cpufreq-hw.c | 11 ++++++++++-
>>
>> Let me also paste impact of this patch - rtla osnoise on entirely idle
>> system (cores 2-7 isolated for Realtime):
>
> Are cores 2-7 the non-housekeeping CPUs[1]?
Yes, since their are isolated for Realtime this is synonymous.
>
> [1] https://lore.kernel.org/lkml/20230223150624.GA29739@lst.de/
Best regards,
Krzysztof
next prev parent reply other threads:[~2023-03-17 8:14 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-15 16:49 [RFC PATCH] cpufreq: qcom-cpufreq-hw: allow work to be done on other CPU for PREEMPT_RT Krzysztof Kozlowski
2023-03-16 12:28 ` Krzysztof Kozlowski
[not found] ` <20230316235705.2235-1-hdanton@sina.com>
2023-03-17 8:13 ` Krzysztof Kozlowski [this message]
2023-03-21 10:04 ` Sebastian Andrzej Siewior
2023-03-21 10:24 ` Krzysztof Kozlowski
2023-03-21 10:57 ` Sebastian Andrzej Siewior
2023-03-21 11:27 ` Krzysztof Kozlowski
2023-03-21 13:39 ` Sebastian Andrzej Siewior
2023-03-23 8:16 ` Krzysztof Kozlowski
2023-03-23 11:37 ` Sebastian Andrzej Siewior
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