From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Benjamin Gaignard <benjamin.gaignard@st.com>
Cc: viresh.kumar@linaro.org, hugues.fruchet@st.com,
mchehab@kernel.org, mcoquelin.stm32@gmail.com,
alexandre.torgue@st.com, pavel@ucw.cz, len.brown@intel.com,
linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-media@vger.kernel.org,
linux-stm32@st-md-mailman.stormreply.com,
linux-arm-kernel@lists.infradead.org,
Patrick Bellasi <patrick.bellasi@arm.com>
Subject: Re: [RFC 0/3] Introduce cpufreq minimum load QoS
Date: Wed, 29 Apr 2020 17:50:04 +0200 [thread overview]
Message-ID: <7657495.QyJl4BcWH5@kreacher> (raw)
In-Reply-To: <20200424114058.21199-1-benjamin.gaignard@st.com>
On Friday, April 24, 2020 1:40:55 PM CEST Benjamin Gaignard wrote:
> When start streaming from the sensor the CPU load could remain very low
> because almost all the capture pipeline is done in hardware (i.e. without
> using the CPU) and let believe to cpufreq governor that it could use lower
> frequencies. If the governor decides to use a too low frequency that
> becomes a problem when we need to acknowledge the interrupt during the
> blanking time.
> The delay to ack the interrupt and perform all the other actions before
> the next frame is very short and doesn't allow to the cpufreq governor to
> provide the required burst of power. That led to drop the half of the frames.
>
> To avoid this problem, DCMI driver informs the cpufreq governors by adding
> a cpufreq minimum load QoS resquest.
This seems to be addressing a use case that can be addressed with the help of
utilization clamps with less power overhead.
Thanks!
next prev parent reply other threads:[~2020-04-29 15:50 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-24 11:40 [RFC 0/3] Introduce cpufreq minimum load QoS Benjamin Gaignard
2020-04-24 11:40 ` [RFC 1/3] PM: QoS: " Benjamin Gaignard
2020-04-24 11:40 ` [RFC 2/3] cpufreq: governor: Use " Benjamin Gaignard
2020-04-24 11:40 ` [RFC 3/3] media: stm32-dcmi: Inform cpufreq governors about cpu load needs Benjamin Gaignard
2020-04-29 15:50 ` Rafael J. Wysocki [this message]
2020-04-29 15:57 ` [RFC 0/3] Introduce cpufreq minimum load QoS Benjamin GAIGNARD
2020-04-29 16:12 ` Valentin Schneider
2020-04-30 7:52 ` Benjamin GAIGNARD
2020-04-30 9:03 ` Rafael J. Wysocki
2020-04-30 13:46 ` Benjamin GAIGNARD
2020-04-30 14:33 ` Valentin Schneider
2020-04-30 15:37 ` Benjamin GAIGNARD
2020-04-30 15:50 ` Valentin Schneider
2020-05-04 9:17 ` Benjamin GAIGNARD
2020-05-20 7:29 ` [Linux-stm32] " Benjamin GAIGNARD
2020-04-29 17:08 ` Vincent Guittot
2020-04-30 9:00 ` Rafael J. Wysocki
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