Ian Smith wrote:
afair, single usb 2.0 device can be as fast as 240 Mbits/sec, not 320 Mbits/sec:On Mon, 2 Jan 2017 11:27:49 +0300, Marat N.Afanasyev wrote: > I wonder is there a speed limit on usb 3.0? I've bought > > ugen0.4: <SanDisk> at usbus0 > umass2 on uhub7 > umass2: <SanDisk Extreme, class 0/0, rev 2.10/0.10, addr 4> on usbus0 > da2 at umass-sim2 bus 2 scbus9 target 0 lun 0 > da2: <SanDisk Extreme 0001> Removable Direct Access SPC-4 SCSI device > da2: Serial Number AA010808161609220143 > da2: 40.000MB/s transfers > da2: 59840MB (122552320 512 byte sectors) > da2: quirks=0x2<NO_6_BYTE> > > that claims 'Up to 245 MBytes/sec read speed' > > and dd shows: > > % dd if=/dev/da2 of=/dev/null bs=1m count=1000 > 1000+0 records in > 1000+0 records out > 1048576000 bytes transferred in 25.688997 secs (40818098 bytes/sec) > > why we have such a limit?Seems you've plugged it into a USB 2 port, not USB 3 At least you're getting full USB 2 performance (40MB/s) Check if you have one or more USB 3 ports with 'dmesg | grep xhci' cheers, Ian _______________________________________________ freebsd-stable@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
% dd if=/dev/da2 of=/dev/null bs=1m count=1000 1000+0 records in 1000+0 records out 1048576000 bytes transferred in 34.026227 secs (30816699 bytes/sec) it's the same drive in usb 2.0 port And I do have usb 3.0: % grep xhci /var/run/dmesg.bootxhci0: <XHCI (generic) USB 3.0 controller> mem 0xfeaf8000-0xfeafffff irq 17 at device 0.0 on pci5
xhci0: 64 bytes context size, 64-bit DMA usbus0 on xhci0xhci0: <XHCI (generic) USB 3.0 controller> mem 0xfeaf8000-0xfeafffff irq 17 at device 0.0 on pci5
xhci0: 64 bytes context size, 64-bit DMA usbus0 on xhci0 and I tried this thumb drive is in usb 3.0 port first, of course. -- SY, Marat
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