Date: | 28 Apr 2022 |
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Plugin_daos_sampler - man page for the LDMS DAOS sampler plugin
The daos_sampler plugin collects DAOS telemetry from local DAOS I/O Engine instances.
The daos_sampler plugin uses the sampler_base base class. This man page only covers the configuration attributes specific to this plugin; see ldms_sampler_base.man for the attributes of the base class.
- name=<plugin_name>
- This MUST be daos_sampler.
- producer=$HOSTNAME
- The $HOSTNAME variable provides a good unique producer ID.
- engine_count=2
- The default is 2; don't change it unless the number of per-server engines is different.
- target_count=8
- The default is 8; don't change it unless the number of targets per engine is different.
SAMPLE FORMAT
The DAOS telemetry is exposed as a set of trees, with the system name as the root:
$system/$rank/$target - Per-engine target metrics not associated with a pool $system/$rank/$pool - Per-engine top-level pool metrics $system/$rank/$pool/$target - Per-engine target metrics associated with a pool
Under each tree is a set of metrics in either counter or gauge format. Counters are monotonically-increasing uint64 values; gauges are instantaneous-read uint64 values that can vary up or down. Certain gauge metrics may have associated statistics in min/max/count/mean/stddev format.
EXAMPLE SAMPLER USAGE
Start ldmsd as usual, for example:
$ ldmsd -m1MB -x sock:10444 -F -c /path/to/sampler.conf
NOTE: The default memory size (512KB) may be too small for the number of metrics collected. Larger sizes may be specified for a large number of pools.
Once ldmsd is running, it is possible to check that the DAOS telemetry appears in the output of ldms_ls, for example:
$ ldms_ls -h localhost -x sock -p 10444 -l daos_server/0/0: consistent, last update: Wed Aug 25 18:40:25 2021 +0000 [653335us] M char[] system "daos_server" M u32 rank 0 M u32 target 0 D u64 io/latency/update/256B 0 D u64 io/latency/update/256B/min 0 D u64 io/latency/update/256B/max 0 D u64 io/latency/update/256B/samples 0 D d64 io/latency/update/256B/mean 0.000000 D d64 io/latency/update/256B/stddev 0.000000 D u64 io/latency/update/32KB 611 D u64 io/latency/update/32KB/min 611 D u64 io/latency/update/32KB/max 611 D u64 io/latency/update/32KB/samples 1 D d64 io/latency/update/32KB/mean 611.000000 D d64 io/latency/update/32KB/stddev 0.000000 D u64 io/latency/update/64KB 0 D u64 io/latency/update/64KB/min 0 D u64 io/latency/update/64KB/max 0 D u64 io/latency/update/64KB/samples 0 D d64 io/latency/update/64KB/mean 0.000000 D d64 io/latency/update/64KB/stddev 0.000000 D u64 io/latency/update/128KB 1018 D u64 io/latency/update/128KB/min 567 D u64 io/latency/update/128KB/max 1214 D u64 io/latency/update/128KB/samples 8 D d64 io/latency/update/128KB/mean 828.000000 D d64 io/latency/update/128KB/stddev 238.011404