On Tue, Aug 11, 2009 at 10:06 PM, Alan Stern<stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 11 Aug 2009, cihan öztürk wrote: > >> Thank you very much for advising the tool usbmon. >> I have implemented a parser that converts its outputs to the format suitable, >> to our requirements, and it all helped us very much for analysing the >> USB traffic. >> We realized that connecting two devices doesn't increase the throughput >> to the numbers I have mentioned before. I think we lose most of the packets >> that we thought were transferred, actually that's what usbmon outputs. >> Anyway, I will write a more detailed explanation when we complete our tests. >> I just wonder if usbmon is a tool that successfully captures ALL USB traffic >> between the custom usb driver and the host controller driver, along the >> bus we are sniffing. Can we trust the results of usbmon without doubt? >> I want to make sure about this because we will base tha analysis of our >> studies on this tool if we can trust its outputs are completely full, >> without any packets missing.. > > It is possible for usbmon to lose events. You can tell if this happens > because the Bs file (where B is the bus number) contains a count of > lost events. > > Oddly, this fact doesn't seem to be mentioned explicitly in > Documentation/usb/usbmon.txt. > > Alan Stern > > I am not sure how to obtain Bs file. I tried #cat /sys/kernel/debug/usbmon/1u > logs1.txt in one shell to sniff 1st bus (which works perfectly) and # cat /sys/kernel/debug/usbmon/1s > events1.txt in another shell to capture events of 1st bus, but this command immediately returned, outputting a file with the text "nreaders 0 events 8626 text_lost" What am i doing wrong? -- 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
