On Mon, Jul 08, 2019 at 04:02:17PM +0300, Janne Blomqvist wrote: > > Good point. If you happen to have a USB stick handy, can you try the > simple C benchmark program at > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91030#c38 ? > > (the kernel will coalesce IO's by itself, so the granularity of IO > syscalls is not necessarily the same as the actual IO to devices. > Network filesystems like NFS/Lustre/GPFS may have less latitude here > due to coherency requirements etc.) >
Writing to USB is constrained be the speed of the bus. kernel: ugen6.3: <Kingston DataTraveler 3.0> at usbus6 kernel: umass1 on uhub0 kernel: umass1: <Kingston DataTraveler 3.0, class 0/0, rev 2.10/0.01, addr 3> on usbus6 kernel: da1 at umass-sim1 bus 1 scbus5 target 0 lun 0 kernel: da1: <Kingston DataTraveler 3.0 > Removable Direct Access SPC-4 SCSI device kernel: da1: Serial Number 0C9D927F0A77F330A89D1210 kernel: da1: 40.000MB/s transfers kernel: da1: 29510MB (60437492 512 byte sectors) kernel: da1: quirks=0x2<NO_6_BYTE> Mounting the thumb drive as a MSDOSFS on FreeBSD. Test using 100000000 bytes Block size of file system: 16384 bs = 1024, 8.86 MiB/s bs = 2048, 7.52 MiB/s bs = 4096, 7.32 MiB/s bs = 8192, 7.32 MiB/s bs = 16384, 7.40 MiB/s bs = 32768, 7.40 MiB/s bs = 65536, 5.57 MiB/s bs = 131072, 7.43 MiB/s bs = 262144, 5.55 MiB/s bs = 524288, 7.43 MiB/s bs = 1048576, 5.56 MiB/s bs = 2097152, 7.39 MiB/s bs = 4194304, 7.62 MiB/s bs = 8388608, 5.58 MiB/s bs = 16777216, 7.42 MiB/s bs = 33554432, 5.59 MiB/s bs = 67108864, 4.77 MiB/s For the same binary, writing to a UFS2 on a SATAII SSD Test using 100000000 bytes Block size of file system: 32768 bs = 1024, 123.09 MiB/s bs = 2048, 210.30 MiB/s bs = 4096, 184.75 MiB/s bs = 8192, 237.28 MiB/s bs = 16384, 244.42 MiB/s bs = 32768, 243.20 MiB/s bs = 65536, 253.77 MiB/s bs = 131072, 243.32 MiB/s bs = 262144, 238.81 MiB/s bs = 524288, 243.87 MiB/s bs = 1048576, 246.55 MiB/s bs = 2097152, 242.39 MiB/s bs = 4194304, 243.68 MiB/s bs = 8388608, 243.88 MiB/s bs = 16777216, 242.21 MiB/s bs = 33554432, 253.19 MiB/s bs = 67108864, 178.29 MiB/s -- Steve
