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memtier_benchmark rate-limiting oscillations on Amazon Linux 2023 #361

@kachkin43

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@kachkin43

Noticed a phenomenon on Amazon Linux 2023. It ships with CONFIG_HZ=100 (vs 250-1000 on other distributions). The following command shows ops rate oscillations:

memtier_benchmark -s 123.232.44.53 -p 14469 -c 10 -t 2 --pipeline=2 --test-time=3660 --data-size=1024 --ratio=1:10 --hide-histogram --key-pattern P:P --key-minimum=1 --key-maximum=5000000 -R --rate-limiting=1000 --key-prefix=<....>

Image

Wondering if rate-limiting timer resolution is affected by CONFIG_HZ.
Setting EVENT_PRECISE_TIMER=1 eliminates the oscillations:

Image

EVENT_PRECISE_TIMER=1 memtier_benchmark -s ...
Rebuilding the kernel with CONFIG_HZ=1000 also fixes it.

Edit: memtier version=2.2.1

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