[v4,0/9] examples/vm_power: 100% Busy Polling
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Message ID 20180713142302.34576-1-david.hunt@intel.com
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Hunt, David July 13, 2018, 2:22 p.m. UTC
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 ratio 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.

The guest_cli app has also been modified to allow sending of a
policy of type BRANCH_RATIO where all of the cores included in
the policy will be monitored by the vm_power_manager oob thread.

v2 changes:
   * Add the guest_cli patch into this patch set, including the
     ability to set the policy to BRANCH_RATIO.
     http://patches.dpdk.org/patch/40742/
   * When vm_power_manger receives a policy with type BRANCH_RATIO,
     add the relevant cores to the monitoring thread.

v3 changes:
   * Added a command line parameter to allow changing of the
     default branch ratio threshold. can now use -b 0.3 or
     --branch-ratio=0.3 to set the ratio for scaling up/down.

v4 changes:
   * Removed some un-needed header file includes

[1/9] examples/vm_power: add check for port count
[2/9] examples/vm_power: add core list parameter
[3/9] examples/vm_power: add oob monitoring functions
[4/9] examples/vm_power: allow greater than 64 cores
[5/9] examples/vm_power: add thread for oob core monitor
[6/9] examples/vm_power: add port-list to command line
[7/9] examples/vm_power: add branch ratio policy type
[8/9] examples/vm_power: add cli args to guest app
[9/9] examples/vm_power: make branch ratio configurable

Comments

Thomas Monjalon July 20, 2018, 10:06 p.m. UTC | #1
13/07/2018 16:22, David Hunt:
> [1/9] examples/vm_power: add check for port count
> [2/9] examples/vm_power: add core list parameter
> [3/9] examples/vm_power: add oob monitoring functions
> [4/9] examples/vm_power: allow greater than 64 cores
> [5/9] examples/vm_power: add thread for oob core monitor
> [6/9] examples/vm_power: add port-list to command line
> [7/9] examples/vm_power: add branch ratio policy type
> [8/9] examples/vm_power: add cli args to guest app
> [9/9] examples/vm_power: make branch ratio configurable

Applied, thanks

Some features could be hosted in a DPDK library.
It has been agreed in the technical board to use examples
as a staging area, but it must re-considered regularly
whether the code must stay, move or be removed.