On Tue, 2011-06-07 at 13:02 +0200, Remy Bohmer wrote: > Hi All, > > 2011/6/7 Peter Zijlstra <peterz@xxxxxxxxxxxxx>: > > On Tue, 2011-06-07 at 11:40 +0200, Armin Steinhoff wrote: > >> Hi, > >> > >> when I read all these confusing statements here ( in german it looks > >> like an "Eiertanz") ... I can only say: > >> > >> - do the basic stuff in a minimal kernel driver > >> - use UIO (or VFIO for PCI devices) > > > > I see no requirement for any of those horrid things to be used. You can > > write a full on proper kernel driver, it just cannot set kernel thread > > priorities to a sane value (let them all default to 50 or so). > > > > Then have a user space script or whatever set the kthread priorities. > >> and you get clean control about your real-time priorities. > >> I think changing the priorities of "interrupt threads" inside the kernel > >> could lead to strange race conditions in the kernel. > > Well, I 100% agree that it must be under full userspace control to be > able to set the priorities. But, the kernel default assumption of > starting everything at 50 is wrong as well. > Imagine the following situation: > * Realtime application is running and has threads active in the range > of prios 20 - 90. > * Now bring up a network device, it immediately starts spamming the > system at prio 50 _before_ you have the chance to set it below 20 by > means of chrt. > * RT behaviour is gone! Good point I guess, Thomas should we default to 1 for everything? -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
