goschedstats: add cluster setting to always do short sampling #133459
+98
−6
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The adaptive sampling, with the long period equal to 250ms, can result in sluggish changes in the number of AC slots, resulting in unnecessary queueing. The 1ms sampling is cheap, even on an idle roachprod node.
Effect of enabling this on an idle node -- the CPU utilization does not change
A 15s cpu profile on this 8vCPU node shows only 20ms in goschedstats and callbacks.
Fixes #131766
Epic: none
Release note (ops change): The
goschedstats.always_use_short_sample_period.enabled setting should be set to true for any serious production cluster, to prevent unnecessary queuing in admission control CPU queues.