From: Doug Smythies <dsmythies@telus.net>
To: Pratik 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 v3 0/2] CPU-Idle latency selftest framework
Date: Fri, 9 Apr 2021 07:26:38 -0700 [thread overview]
Message-ID: <CAAYoRsXqUpkVxDuRUoapBJ__EUPbMBSWJ7QigVcKbr6ApRxzbg@mail.gmail.com> (raw)
In-Reply-To: <0a4b32e0-426e-4886-ae37-6d0bdafdea7f@linux.ibm.com>
On Fri, Apr 9, 2021 at 12:43 AM Pratik Sampat <psampat@linux.ibm.com> wrote:
> On 09/04/21 10:53 am, Doug Smythies wrote:
> > I tried V3 on a Intel i5-10600K processor with 6 cores and 12 CPUs.
> > The core to cpu mappings are:
> > core 0 has cpus 0 and 6
> > core 1 has cpus 1 and 7
> > core 2 has cpus 2 and 8
> > core 3 has cpus 3 and 9
> > core 4 has cpus 4 and 10
> > core 5 has cpus 5 and 11
> >
> > By default, it will test CPUs 0,2,4,6,10 on cores 0,2,4,0,2,4.
> > wouldn't it make more sense to test each core once?
>
> Ideally it would be better to run on all the CPUs, however on larger systems
> that I'm testing on with hundreds of cores and a high a thread count, the
> execution time increases while not particularly bringing any additional
> information to the table.
>
> That is why it made sense only run on one of the threads of each core to make
> the experiment faster while preserving accuracy.
>
> To handle various thread topologies it maybe worthwhile if we parse
> /sys/devices/system/cpu/cpuX/topology/thread_siblings_list for each core and
> use this information to run only once per physical core, rather than
> assuming the topology.
>
> What are your thoughts on a mechanism like this?
Yes, seems like a good solution.
... Doug
next prev parent reply other threads:[~2021-04-09 14:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-04 8:33 [RFC v3 0/2] CPU-Idle latency selftest framework Pratik Rajesh Sampat
2021-04-04 8:33 ` [RFC v3 1/2] cpuidle: Extract IPI based and timer based wakeup latency from idle states Pratik Rajesh Sampat
2021-04-04 8:33 ` [RFC v3 2/2] selftest/cpuidle: Add support for cpuidle latency measurement Pratik Rajesh Sampat
2021-04-09 5:23 ` [RFC v3 0/2] CPU-Idle latency selftest framework Doug Smythies
2021-04-09 7:43 ` Pratik Sampat
2021-04-09 14:26 ` Doug Smythies [this message]
2023-09-11 5:36 Aboorva Devarajan
2023-09-25 5:06 ` Aboorva Devarajan
2023-10-12 4:48 ` Aboorva Devarajan
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