Roman Puchkovskiy created IGNITE-16879:
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Summary: Estimate time-to-write-cp-page and time-to-fsync-cp-page
empirically
Key: IGNITE-16879
URL: https://issues.apache.org/jira/browse/IGNITE-16879
Project: Ignite
Issue Type: Improvement
Components: persistence
Reporter: Roman Puchkovskiy
The speed-based throttling (implemented in
SpeedBasedMemoryConsumptionThrottlingStrategy) tries to estimate how much time
is needed to fully write a checkpoint to disk. To write a page to disk, we not
only need to pass it to the OS for writing (which takes time), but also fsync
it to disk (which also takes some time).
When estimating the time needed to write a checkpoint, the speed-based throttle
needs an estimation of how much time it is needed to write a page and how much
time is needed to fsync it. Currently, a naive approximation is used: page
writing time is equal to page fsyncing time.
In reality, this is not true, so the speed estimations are off: the more the
ratio between writing and syncing time differs from 1, the worse our estimation
is.
The idea is to actually measure the average time to write a page and fsync a
page to disk and then use these measured values to obtain better estimations.
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