On Wed, 28 Apr 2010, Hakan [iso-8859-9] Bayýndýr wrote: > Hello all, > > Anybody have any idea about why some USB flash disks show different writing > speeds under Linux and Windows? For example the Sandisk's 32GB Extreme Contour > drive can sustain ~17MB/second while copying big files under Windows but the > maximum speed under Linux is ~4MB/second for the exact file. On the contrary, > another disk I tested, a Corsair FlashVoyager GT 16GB can perform at its rated > speeds (writing) on both platforms. Reading speed on both devices on both > platforms is same and within their specs (25+ MB/second). > > My initial investigation pointed to queue depth difference of the Windows and > Linux. I'll be very happy if someone can enlighten me about the situation. It might be related to your choice of scheduler. Some people have claimed that the default CFQ scheduler tends to slow down transfers. You can get detailed timing information about the data transfers by using usbmon. See Documentation/usb/usbmon.txt for instructions. Alan Stern -- 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
