Originally Posted by jakiiski
browsing the scores through and doing some trialling of my own as well, there's an issue I think with the Native disk write score. It seems to be all over the place and several devices report scores between 4-12 points or so. I do not think those devices are that slow. Could the benchmark be explained for that part, what does it do and how does it measure the performance?
I did some more trials on this and turns out it's depending on some of the tunables, most notably in my case it is highly dependent on the background dirty bytes. I.e. if I set that to be a of a high value I get good scores - so seems this benchmark is not doing a flush() on the file operations and thus it's really not measuring the true file system speed to the actual end memory/disk device. It's testing more of what happens in the filesystem caches.
You can try it out yourself, all you need is adb connection.
echo 5 >dirty_background_ratio
or you can also set the absolute byte value, too.
echo 10485760 >dirty_background_bytes
the original values depend on what your version of Linux/Android has written originally to those. You set either the ratio or bytes, not both at the same time.