On Wed, 23 Aug 2017, David Mosberger wrote: > Alan, > > On Wed, Aug 23, 2017 at 10:30 AM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > >> Does anybody know why HCD_BH is not enabled in ohci-hcd.c? > > > > Because it changes the semantics of isochronous and interrupt > > streaming. See for example commits 9118f9eb4f1e, 24f531371de1, and > > 46c73d1d3ebc. > > Cool, this is very helpful. So if one doesn't care about isochronous > transfers, worst case > would be that interrupt transfers might be handled less efficiently > than they should be, > but other than that, OHCI would work fine with HCD_BH? Basically, yes. > I did just try turning on the flag in ohci-hcd.c and it makes a > significant difference: > during a 1-minute test run, it reduces the number of missed deadlines in my > soft-realtime task from 757 to 49! Have you tried using the RT patch set? It may or may not be practical for you, but it could end up making an even larger difference. 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
