Re: [PATCHv2 2/3] cpupower: mperf_monitor: Introduce per_cpu_schedule flag

[shuah <shuah@kernel.org>]

On 10/25/19 4:39 AM, Thomas Renninger wrote:
> Hi Natarajan,
> 
> sorry for answering that late.
> I post on top as it doesn't fit to the patch context:
> 
> While I like the 2 other patches, especially the first preparing for
> a generic "ensure to always run on the measured CPU at measure time"
> interface..., this patch does make use of it in a very static manner.
> 
> I then tried to get this more generic..., without any outcome for now.
> 
> If someone likes to play with this, my idea would be:
> 
> - the monitors need cpu_start() and cpu_stop() callbacks to register
> - either start(), stop() and/or cpu_start(), cpu_stop() callbacks have to
>    be provided by a monitor.
> - current behavior is only start/stop which means the whole per_cpu logic
>    resides inside the monitor
> - if cpu_start/cpu_stop is provided, iterating over all cpus is done in
>    fork_it and general start/stop functions are an optionally entry point
>    before and after the per_cpu calls.
> 
> Then the cpu binding can be done from outside.
> Another enhancement could be then to fork as many processes as there are CPUs
> in case of per_cpu_schedule (or an extra param/flag) and then:
> 
> - Bind these forked processes to each cpu.
> - Execute start measures via the forked processes on each cpu
> - Execute test executable (which runs in yet another fork as done already)
> - Execute stop measures via the forked processes on each cpu
> 
> This should be ideal environment to not interfere with the tested executable.
> It would also allow a nicer program structure.
> 

It will be good to capture these ideas in the ToDo file.

Natarajan! WOuld you like to send a patch updating the ToDo file with
these ideas?

thanks,
-- Shuah