On 04/11/2014 04:33 PM, David Miller wrote: > From: Rik van Riel <[email protected]> > Date: Thu, 10 Apr 2014 11:57:06 -0400 > >> @@ -330,7 +334,11 @@ void irq_enter(void) >> >> static inline void invoke_softirq(void) >> { >> - if (!force_irqthreads) { >> + /* >> + * If force_irqthreads is set, or if we looped in __do_softirq this >> + * jiffie, punt to ksoftirqd to prevent userland starvation. >> + */ >> + if (!force_irqthreads && this_cpu_read(softirq_looped) != jiffies) { > > If we do this, which I'm not convinced of yet, I think we should use two > jiffies as the cutoff.
I am not fully convinced, either. This patch mostly just illustrates the problem, and gives something that solves Jiri's immediate problem. It is quite likely that there is a better way to solve the problem of: 1) softirq handling starving out userspace processing, 2) which could be solved by moving the userspace process elsewhere, and 3) shifting softirq processing to ksoftirqd A working patch seems to be one of the better ways to start a discussion, though. If anybody has a nicer idea on how to solve the problem, I'd even be willing to implement your idea, and give Jiri another patch to test :) -- All rights reversed -- 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/
