netbsd@geekrants.org wrote:

> Just did the same test on my Qube 2, tlp0, and get quite a bit more 
> performance than you.. weird.

TX (wd->tlp) speed may depend on the HDD xfer rate, how much memory
your qube has, and how much data is cached at that time etc.
RX (tlp->wd) speed may depend on the HDD performance and how your
file system is mounted, with or without softdep etc.

Specific benchmarks and dmesg might help to solve performance issue...
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Izumi Tsutsui