Mike Larkin <mlar...@nested.page> writes: > On Sat, Jun 04, 2022 at 06:24:36PM -0700, Greg Steuck wrote: >> I observe ~90x difference in bandwidth between Linux and OpenBSD on the >> same hardware. The test case is reading big files from a USB-attached >> flash drive[0]. The drive is plugged into a sole USB-c port on the back >> of the motherboard. >> >> On Linux I get about 900MB/s. OpenBSD shows ~10MB/s: >> >> # dd if=/dev/sd1i of=/dev/null bs=1M count=1000 >> 1000+0 records in >> 1000+0 records out >> 1048576000 bytes transferred in 95.617 secs (10966340 bytes/sec) >> > > does /dev/rsd1i make any difference?
I was somehow sure I tried rsd1i before, but now I can see a 17x difference: # dd if=/dev/rsd1i of=/dev/null bs=1M count=1000 1000+0 records in 1000+0 records out 1048576000 bytes transferred in 6.038 secs (173,659,835 bytes/sec) Looking at iostat I see that using the "r" device causes transactions to go up to 64KB/t. Now, the real issue I had was with a slow ext2 file systems on the drive. I get 10MB/s reading the files and I observe 4KB/t in iostat. So, yeah, I can get faster transfers which means xhci and umass are capable of more than filesystems (at least ext2) extract out of them. Thanks Greg
