[patrakov]

> Is there an experiment you'd recommend to reliably show this behavior on such a SSD?

  fio --name 4k-write --rw=write --bs=4k --size=1G --filename=fio.file --ioengine=libaio --sync=1 --time_based --runtime=60 --write_iops_log=ssd --log_avg_msec=1000 --randrepeat=0 --refill_buffers=1

Then examine ssd_iops.1.log.

Results from Apacer AS350 1TB: https://pastebin.com/F6pr5g29 - the first field is the timestamp in milliseconds, the second one is the write IOs completed since the previous line.

EDIT: I was told that the test above is invalid and that I should add --direct=1. OK, here is the new log, showing the same: https://pastebin.com/Wyw6r9TC - note that some timestamps are completely missing, indicating that the SSD performed zero IOs in that second.

You may want to repeat the experiment a few times.