The collect tool executes various Linux and system commands to gather
data into an archived collect bundle.
System administrators often need to run collect on busy, in-service
systems. During such operations, they have reported excessive CPU
usage, which can lead to undesirable CPU spikes caused by certain
collect operations.
While the collect tool already employs throttling for ssh and scp,
its data collection and archiving commands currently lack similar
safeguards.
This update introduces the following enhancements to mitigate CPU
spikes and improve performance on heavily loaded in-service servers:
- removed one unnecessary tar archive operation.
- add tar archive checkpoint option support with action handler
- removed one redundant kubelet api-resources call in the
containerization plugin.
- add --chunk-size=50 support to all in one kubelet get api-resources
command to help throttle this long running heavyweight command.
50 seems to yield the lowest k8s api latency as measured with the
k8smetrics tool.
- launch collect plugins with 'nice' and 'ionice' attributes.
- add 'nice' and 'ionice' attributes to select commands.
- add sleep delays after known cpu intensive data collection commands.
- remove unnecessary -v (verbose) option to all tar commands.
- add a run_command utility that times the execution of commands
and adaptively adds a small post execution delay based on how
long that command took to run.
- reduce the cpu impact of the containerization plugin by adding
periodic delays.
- added a few periodic delays in long running or cpu intensive plugins
- create a collect command timing log that is added to each the
host collect tarball.
- timing log file records how long it took for each plugin to run as
well as commands called with the new run_command function.
- fixed issue in networking plugin.
- added a 60 second timeout for the 'lsof' heavyweight command.
- fixed delimiter string hostname in all plugins.
- increase the default global timeout from 20 to 30 minutes.
- increase the default collect_host timeout from 600 to 900 seconds.
- incremented tool minor version.
These improvements aim to minimize the performance impact of running
collect on busy in-service systems.
Note: When a process is started with nice, its CPU priority is
inherited by all threads spawned by that process.
However, it does not restrict the total CPU time a process
or its threads can use when no contention exists.
Test Plan:
PASS: Verify build and install of collect package.
PASS: Verify collect runtime is not substantially longer.
PASS: Verify tar checkpoint handling on busy system where checkpoint
action handler detects and invokes system overload handling.
PASS: Verify some CPU spike reduction compared to before update.
Regression:
PASS: Compare collect bundle size and contents before and after update.
PASS: Soak collect on busy/overloaded AIO SX system.
PASS: Verify report tool reports the same data before/after update.
PASS: Verify multi-node collect
Closes-Bug: 2090923
Change-Id: If698d5f275f4482de205fa4a37e0398b19800777
Signed-off-by: Eric MacDonald <eric.macdonald@windriver.com>
94afab2a6b