[dpdk-dev,v1,0/6] examples/vm_power: 100% Busy Polling

Message ID 20180607073705.32895-1-david.hunt@intel.com (mailing list archive)


Hunt, David June 7, 2018, 7:36 a.m. UTC
  This patch set adds the capability to do out-of-band power
monitoring on a systemi by detecting when a core is doing 100%
busy polling, but not handling any packets.

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.

[1/6] examples/vm_power: add check for port count
[2/6] examples/vm_power: add core list parameter
[3/6] examples/vm_power: add oob monitoring functions
[4/6] examples/vm_power: allow greater than 64 cores
[5/6] examples/vm_power: add thread for oob core monitor
[6/6] examples/vm_power: add port-list to command line