On Wed, 7 Nov 2012, Chris Stankevitz wrote: > Hello, > > Background: I'm running an experiment that is sensitive to USB > latency of a few milliseconds. During a typical overnight run I > encounter a handful such "high latency events" and I am trying to > understand why they happen. If you can recommend kernel > settings/hacks that will decrease USB latency, please share! Run with non-USB interrupts disabled on a single-processor system. Seriously, any other interrupt can increase latency for what you're interested in. If you need latencies under a couple of ms, USB probably isn't a good choice. > === > > Question: How can I retrieve a count of USB transmissions that failed > or were retransmitted (similar to ifconfig on ethernet)? I am using > bulk transfers. The host controller drivers do not keep track of retransmission information. You would have to change the driver you are using. > If you do not answer this question, can you instead recommend > documentation that will shed light on the subject? Can you recommend > somewhere else for me to ask this question? The USB specifications are freely avaible at www.usb.org. The USB-2.0 spec has many sections that are quite readable. 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
