Context: I'm on a Toshiba 512 GB NVMe (Model: KXG50ZNV512G)
I'm seeing this weird behaviour while benchmarking Postgres on ZFS-on-Linux (via
pgbench), where the second and third runs of a benchmark are progressively slower than the first run.
Here is what is happening:
client=1 | 770 => 697 | 10% reduction in TPS client=4 | 2717 => 2180 | 24% reduction in TPS client=8 | 4579 => 3339 | 37% reduction in TPS client=12 | 4219 => 4175 | 01% reduction in TPS client=48 | 5902 => 5623 | 05% reduction in TPS client=96 | 7094 => 6739 | 05% reduction in TPS
I'm re-running these tests and the early numbers indicate that the 3rd run is slower than the 1st and 4th is slower than the 3rd.
Could the lack of TRIM support on ZFS-on-Linux causing this - https://github.com/zfsonlinux/zfs/pull/8255 ?