Am Donnerstag, 7. Mai 2009 16:35:57 schrieb Alan Stern: > On Thu, 7 May 2009, Oliver Neukum wrote: > > On a fundamental note, thinking about this in terms of numbers of URBs > > is strictly speaking wrong. We need to limit data in flight. For > > efficiency we should make buffers as large as possible within that limit. > > But for latency you should submit URBs as soone as possible within that > limit, which generally means small buffers. This is true only if the device's buffer would run dry. But if no URB is in flight, a URB should be written right away. > How about setting the upper limit to URBs in flight based on the baud > rate? Faster transfers deserve more URBs, right? Assuming some > minimum number of bytes per URB (4? 8?), there should be enough URBs to > fill a pipeline whose length is around 5 ms or so (interrupt latency). Hm, you say many URBs can complete before an interrupt handler can react? Regards Oliver -- 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
