Fix excessive memory allocation for sched_times (#320)#389
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florianl
approved these changes
Mar 18, 2025
gnurizen
approved these changes
Mar 18, 2025
rockdaboot
reviewed
Mar 19, 2025
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| // second (1000hz) multiplied by an average time a task remains off CPU (3s), | ||
| // scaled by the probability of capturing a trace. | ||
| adaption["sched_times"] = (4096 * cfg.OffCPUThreshold) / support.OffCPUThresholdMax |
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Not a blocker, but it is not obvious to me how 4096 reflects the mentioned "average time a task remains off CPU (3s)". How exactly has the number 4096 been determined and is this the the best value or does it need further refinement?
rockdaboot
approved these changes
Mar 19, 2025
This was referenced Apr 4, 2025
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Summary
On my 16 core local system (VM, possibleCPUs:128, onlineCPUs:16), the previous logic allocated more than 5GB of kernel memory as worst-case (with
off-cpu-thresholdset to 1000) and the agent took ~20 seconds to start due to swapping.This PR reduces the worst-case down to 5MB.
Fixes #320.
Also see #320 (comment).