meta-ibm: Add telemetry bbappend

Adding telemetry bbappend to customize telemetry meson options
for IBM. IBM has different needs than upstream for telemetry capacity
in terms of numbers of sensors readings and rate of requests.
bbappend file allows IBM to stay up to date with upstream Telemetry
while maintain custom build options more suited to IBM's usecases.

Increase meson option for total maximum Metrics/MetricProperties
limit from 200 to 300. For IBM management agent use cases (HMC), the max
number of Metrics needs to greater than 200.

Also for IBM management agent use cases, telemetry reports need a higher
append limit for metric readings. 32768 was determined as
1) a power of 2,
2) higher than HMC's current usage,
3) Ability to collect one hour of data for 250 sensors reading
once every 30 seconds ==> a general guess as to maximum readings
needed in one report.

Testing for maximum metrics increase:
- Monitored CPU usage of bmcweb for both rainier and
  everest systems. bmcweb usage spiked for around 2 seconds with 300
  MetricProperty MRD.
- MRD was periodic on 15 interval with 300 MetricProperties averaged
  over 30 seconds on everest system with 360 sensors. Max bmcweb usage
  was 9% for brief instant when MRD post call is made.

Testing for appendLimit increase:
- Set AppendLimit up to 11000 with 150 sensors on 400+ sensor system.
- Monitored 'top' CPU usage for telemetry binary and bmcweb binary
  which never ran above 5%. AppendLimit generated new metric entries
  for the report.
- Retrieve report did seem to take a little longer as report grew but
  not significantly.
- Tested various other lower limits and sensors

Signed-off-by: Ali Ahmed <ama213000@gmail.com>
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
Change-Id: I418c3e90c565770cd59b02c294754ff98df29a55
diff --git a/meta-ibm/recipes-phosphor/telemetry/telemetry_%.bbappend b/meta-ibm/recipes-phosphor/telemetry/telemetry_%.bbappend
new file mode 100644
index 0000000..089963c
--- /dev/null
+++ b/meta-ibm/recipes-phosphor/telemetry/telemetry_%.bbappend
@@ -0,0 +1,4 @@
+EXTRA_OEMESON:append:p10bmc = " \
+    -Dmax-append-limit=300 \
+    -Dmax-reading-parameters=32768 \
+"