Hello, hm - interesting, the performance could be really increased. But only a little bit - its now around 60kb/sec (okay a factor of nearly 2) - the average delay is still around 1 msec. Well faster but not at a real USB limit. I played around with the count value and 10 seems to be one of the best.
Any other Ideas? The Windows XP shows me a pretty old USB Host adaptor, is there a way to change to a newer one? The chipset is now nearly 11 years old :-) Best regards, Erik Xin, Xiaohui wrote: > Erik, > Did you use uhci or ehci controller in qemu? If uhuci, then > Don’t know we are met the same issue or not. May you try the patch to see if > it has some effect or not? We observe it has effect on native qemu side. > > The patch is simple but experimental, you may try to modify the "count" > number as you need to see a effect. > > Thanks > Xiaohui > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf > Of Erik Rull > Sent: 2009年3月19日 5:42 > To: [email protected] > Subject: usb-linux.c - delay between USB URBs > > Hello, > > my problem is still the same - the USB key has only a transfer rate of ~ 2 > MB / min through the virtualization. > > So I did some debugging in usb-linux.c - first I switched on debugging. > The debug output was way to much so I added a timestamp calculation between > a) start and end of async transfer and b) end of one and start of the next > block (each block is 64 bytes large). > The transfer rate of the driver itself is ~ 200kByte / sec - quite fine and > much faster than the complete chain (only ~32kByte / sec). > The delay between one and the next packet is ~2msec (transfer of 2MByte > from USB key to HDD measured)! that means, 64 bytes are transferred then a > pause of nearly 2msec is placed and then the next 64 bytes are sent to the > driver. This fits nearly exactly my measured transfer rate of 32kByte /sec > (64 Bytes / 2msec => 32kByte / sec). > > Where do the 2 msec come from? I have no real other processes running that > could interfere here. In the Windows guest there is nothing else but the > windows explorer and some other standard processes running. > Any Idea where to continue searching for these 2msecs?? > > Best regards, > > Erik > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
