Re: [dpdk-dev] [0/9] examples/vm_power: 100% Busy Polling

[Thomas Monjalon <thomas@monjalon.net>]

26/06/2018 11:23, David Hunt:
> This patch set adds the capability to do out-of-band power
> monitoring on a system. It uses a thread to monitor the branch
> counters in the targeted cores, and calculates the branch ratio
> if the running code.
> 
> If the branch ratop is low (0.01), then
> the code is most likely running in a tight poll loop and doing
> nothing, i.e. receiving no packets. In this case we scale down
> the frequency of that core.
> 
> If the branch ratio is higher (>0.01), then it is likely that
> the code is receiving and processing packets. In this case, we
> scale up the frequency of that core.
> 
> The cpu counters are read via /dev/cpu/x/msr, so requires the
> msr kernel module to be loaded. Because this method is used,
> the patch set is implemented with one file for x86 systems, and
> another for non-x86 systems, with conditional compilation in
> the Makefile. The non-x86 functions are stubs, and do not
> currently implement any functionality.
> 
> The vm_power_manager app has been modified to take a new parameter
>    --core-list or -l
> which takes a list of cores in a comma-separated list format,
> e.g. 1,3,5-7,9, which resolvest to a core list of 1,3,5,6,7,9
> These cores will then be enabled for oob monitoring. When the
> OOB monitoring thread starts, it reads the branch hits/miss
> counters of each monitored core, and scales up/down accordingly.

It looks to be a feature which could be integrated in DPDK libs.
Why choosing to implement it fully in an example?