From: Doug Smythies <dsmythies@telus.net>
To: Pratik Rajesh Sampat <psampat@linux.ibm.com>
Cc: rjw@rjwysocki.net, Daniel Lezcano <daniel.lezcano@linaro.org>,
shuah@kernel.org, ego@linux.vnet.ibm.com, svaidy@linux.ibm.com,
Linux PM list <linux-pm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-kselftest@vger.kernel.org, pratik.r.sampat@gmail.com,
dsmythies <dsmythies@telus.net>
Subject: Re: [RFC v4 2/2] selftest/cpuidle: Add support for cpuidle latency measurement
Date: Sun, 25 Apr 2021 13:49:32 -0700 [thread overview]
Message-ID: <CAAYoRsXhH3d8AwBgHD1kyWjw2GUvMQ42br72CfjHTx6NSYKp6w@mail.gmail.com> (raw)
In-Reply-To: <20210412074309.38484-3-psampat@linux.ibm.com>
Hi Pratik,
On Mon, Apr 12, 2021 at 12:43 AM Pratik Rajesh Sampat
<psampat@linux.ibm.com> wrote:
>
> The cpuidle latency selftest provides support to systematically extract,
> analyse and present IPI and timer based wakeup latencies for each CPU
> and each idle state available on the system.
>
> The selftest leverages test-cpuidle_latency module's debugfs interface
> to interact and extract latency information from the kernel.
>
> The selftest inserts the module if already not inserted, disables all
> the idle states and enables them one by one testing the following:
> 1. Keeping source CPU constant, iterate through all the CPUS measuring
> IPI latency for baseline (CPU is busy with cat /dev/random > /dev/null
> workload) and then when the CPU is allowed to be at rest
> 2. Iterating through all the CPUs, sending expected timer durations to
> be equivalent to the residency of the deepest idle state enabled
> and extracting the difference in time between the time of wakeup and
> the expected timer duration
>
> The timer based test produces run to run variance on some intel based
> systems that sport a mechansim "C-state pre-wake" which can
> pre-wake a CPU from an idle state when timers are armed. For systems and
> architectures that don't have this mechansim can leverage timer tests
> with the -i option.
>
> To run this test specifically:
> $ sudo make -C tools/testing/selftests TARGETS="cpuidle" run_tests
>
> There are a few optional arguments too that the script can take
> [-h <help>]
> [-i <run timer tests>]
> [-m <location of the module>]
> [-o <location of the output>]
> [-v <verbose> (run on all cpus)]
> Default Output location in: tools/testing/selftest/cpuidle/cpuidle.log
>
> To run the test without re-compiling:
> $ cd tools/testing/selftest/cpuidle/
> $ sudo ./cpuidle.sh
>
> Signed-off-by: Pratik Rajesh Sampat <psampat@linux.ibm.com>
Reviewed-by: Doug Smythies <dsmythies@telus.net>
...
next prev parent reply other threads:[~2021-04-25 20:49 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-12 7:43 [RFC v4 0/2] CPU-Idle latency selftest framework Pratik Rajesh Sampat
2021-04-12 7:43 ` [RFC v4 1/2] cpuidle: Extract IPI based and timer based wakeup latency from idle states Pratik Rajesh Sampat
2021-04-25 20:47 ` Doug Smythies
2021-04-12 7:43 ` [RFC v4 2/2] selftest/cpuidle: Add support for cpuidle latency measurement Pratik Rajesh Sampat
2021-04-25 20:49 ` Doug Smythies [this message]
2021-04-13 14:52 ` [RFC v4 0/2] CPU-Idle latency selftest framework Doug Smythies
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