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Date: Thu, 21 Jul 2011 18:51:48 +0200 From: Peter Zijlstra <peterz@...radead.org> To: Stephan Bärwolf <stephan.baerwolf@...ilmenau.de> Cc: linux-kernel@...r.kernel.org, Nikhil Rao <ncrao@...gle.com>, Ingo Molnar <mingo@...e.hu> Subject: Re: sched: fix/optimise some issues On Thu, 2011-07-21 at 18:36 +0200, Stephan Bärwolf wrote: > I also remember weak Linus had sth. against "priority inheritance" > (don't ask me what or why - I don't know), > but it would be an honour to me working with you guys to implement > this feature in future kernels. Look at kernel/rt_mutex.c, it as a complete tradition Priority Inheritance implementation :-) The trouble is that it only works for SCHED_FIFO/RR. Now you can extend PI to cover weighted fair queueing, or implement the much simpler proxy execution policy which generalizes to pretty much any scheduling algorithm, see for example the paper: "Timeslice donation in component-based systems" in: http://www.artist-embedded.org/docs/Events/2010/OSPERT/OSPERT2010-Proceedings.pdf Extending that to SMP is the 'interesting' bit.. However that will not solve the true idle thing since some synchronization primitives we have are fundamentally incompatible with any form of PI (including the various ceiling protocols) :-/, see for example the traditional semaphore and completions. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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