nvme performance

[Romain Kang]

Hi all,

> > dd if=/dev/zero of=tempfile bs=1m count=1024

If I understand, the sample dd command is *writing* to the drive, and
the OP is asking about *read* throughput.

To measure the read speed, I think you'd want to take the large file
thus created ("tempfile") and read it back.  E.g.,
# dd if=tempfile of=/dev/null bs=1m

However, tempfile is going to be 1 GB in this case, and might be entirely
buffered in kernel space.  So reading directly from the block device and
writing to /dev/null might be the better measurement for raw read speed,
if that's the actual question.
# dd if=/dev/... of=/dev/null bs=1m count=1024

Best,
Romain Kang                             Disclaimer: I speak for myself alone,
romain at kzsu.stanford.edu                except when indicated otherwise.