Messages in this thread | | | Date | Mon, 27 Feb 2012 09:05:27 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH] Extend mwait idle to optimize away CAL and RES interrupts to an idle CPU -v1 |
| |
On Mon, Feb 27, 2012 at 05:06:46PM +0800, Yong Zhang wrote: > On Sat, Feb 25, 2012 at 05:32:53PM -0800, Paul E. McKenney wrote: > > On Fri, Feb 24, 2012 at 01:41:50PM +0800, Yong Zhang wrote: > > > On Thu, Feb 23, 2012 at 11:34:11AM -0800, Venki Pallipadi wrote: > > > > On Thu, Feb 23, 2012 at 1:30 AM, Peter Zijlstra <peterz@infradead.org> wrote: > > > > > Why not scheduler_ipi()? > > > > > > > > Was trying to avoid irq_enter/exit. As the work here is done in idle > > > > thread context, I though we could avoid enter/exit. > > > > > > It seems we could not. > > > At least RCU need it, see commit c5d753a55, otherwise we will get > > > warning like 'RCU used illegally from extended quiescent state!' > > > > If the use is tracing, then Steven Rostedt's patchset plus use of his > > _rcuidle() tracing variants handles this: > > > > https://lkml.org/lkml/2012/2/7/231 > > > > If this is instead algorithmic use of RCU, a set of patches I have queued > > up for 3.4 will be required. > > scheduler_ipi() doing more than tracing. Will look at your patches :)
Ah! The key question is whether or not the code in question is called both from idle and from non-idle. This will be easiest if the code is called only from idle, in which case you should only need this one:
https://lkml.org/lkml/2012/2/3/498
Thanx, Paul
| |