On Tue, 31 May 2016, Michael Schaller wrote: > Is there anything else I can do to debug this issue further? > Are there any quirks I could try? You can try capturing a usbmon trace of a test transfer. That might provide a clue about where the bottleneck lies. Also, post the dmesg log showing what happens when you plug in the drive. Alan Stern > On Wed, May 18, 2016 at 3:41 PM, Michael Schaller <misch@xxxxxxxxxx> wrote: > > [1.] One line summary of the problem: > > Slow writes with dd on Lexar JumpDrive P20 64GB flash drives connected > > via Intel USB 3.0 host controllers. > > > > > > [2.] Full description of the problem/report: > > Writes on Lexar JumpDrive P20 64GB flash drives are unexpectedly slow. > > With dd we are seeing 45 MB/s while we get the expected 270 MB/s under > > Mac OS X and Windows. This issue is present on all tested flash drives > > of this type and on multiple machines with various Intel USB 3.0 host > > controllers (the data in this report is from a HP EliteBook 840). > > Furthermore the issue is present with kernel 4.6 and older kernels > > (tested with 4.4, 4.2, 3.19 and 3.13). The dmesg output doesn't > > contain any errors and other than the slow write speed there are no > > issues and no oops'. > > > > Write speed under Linux: > > $ sudo dd if=/dev/zero of=/dev/sdb bs=1M count=256 > > 256+0 records in > > 256+0 records out > > 268435456 bytes (268 MB) copied, 5.98705 s, 44.8 MB/s > > > > Write speed under Mac OS X: > > $ sudo dd if=/dev/zero of=/dev/rdisk2 bs=1048576 count=256 > > 256+0 records in > > 256+0 records out > > 268435456 bytes transferred in 0.941998 secs (284963933 bytes/sec) -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
