On Tuesday 02 December 2008, Joakim Tjernlund wrote: > > > Joakim> Won't polling for long periods starve user space? How to > > Joakim> overcome this? > > > > I guess it won't be any worse than the processor being overloaded with > > interrupts - In fact it's better, as there's more real work done. > > It gets the work done faster but will starve everyone else in the process. > The IRQ version doesn't do that.
I've not observed polling from a task context to starve anyone, when done sanely. The opposite is true for doing an order of magnitude more instructions in IRQ context ... > > Joakim> Why use a kernel thread(mpc83xx_spi.0) to do the work? Would > > Joakim> it not be better if the polling was in process context? > > > > I guess that's needed for the async stuff. > > hmm, yes that sounds reasonable. Doesn't sound so to me. Recall that if you have four chipselects, the driver using each chip can submit its own request ... *EVERY* request made to the controller driver is async, entering a queue and coming out when it's done. > One could detect if the operation is > async or not and use process context if it is synchronous. No you can't. ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ spi-devel-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/spi-devel-general
