On Tue, 2007-08-28 at 12:36 -0700, Christoph Lameter wrote: > On Tue, 28 Aug 2007, Peter Zijlstra wrote: > > > On Mon, 2007-08-27 at 15:15 -0700, Christoph Lameter wrote: > > > Hmmmm. One wild idea would be to use a priority futex for the slab lock? > > > That would make the slow paths interrupt safe without requiring interrupt > > > disable? Does a futex fit into the page struct? > > > > Very much puzzled at what you propose. in-kernel we use rt_mutex (has > > PI) or mutex, futexes are user-space. (on -rt spinlock_t == mutex == > > rt_mutex) > > > > Neither disable interrupts since they are sleeping locks. > > > > That said, on -rt we do not need to disable interrupts in the allocators > > because its a bug to call an allocator from raw irq context. > > Right so if a prioriuty futex
futex stands for Fast Userspace muTEX, please lets call it a rt_mutex. > would have been taken from a process > context and then an interrupt thread (or so no idea about RT) is scheduled > then the interrupt thread could switch to the process context and complete > the work there before doing the "interrupt" work. So disabling interrupts > is no longer necessary. -rt does all of the irq handler in thread (process) context, the hard irq handler just does something akin to a wakeup. These irq threads typically run fifo/50 or simething like that. [ note that this allows a form of irq priorisation even if the hardware doesn't. ] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
