On 28 May 2014 12:58, Peter Zijlstra <pet...@infradead.org> wrote: > On Fri, May 23, 2014 at 05:53:03PM +0200, Vincent Guittot wrote: >> Currently the task always wakes affine on this_cpu if the latter is idle. >> Before waking up the task on this_cpu, we check that this_cpu capacity is not >> significantly reduced because of RT tasks or irq activity. >> >> Use case where the number of irq and the time spent under irq is important >> will take benefit of this because the task that is woken up by irq or softirq >> will not use the same CPU than irq (and softirq) but a idle one which share >> its LLC. > > OK, so I'm having a terrible time parsing the above. > > So looking at the patch you make balance false even when this_load==0 > when the effective power/capacity (nico's patches haven't fully sunk in > yet) of this cpu is less than that of the previous cpu. > > Is that right?
yes, > > Now I'm only struggling to understand the rationale for this, its got > LLC in there somewhere, but I'm failing to comprehend. Ah.. i have probably overestimated the fact that wake_affine was only done at MC or SMT level but after reading more deeply the glags configuration of all sched_domain level , my assumption is not true. So I need to test sd flag to make sure that their share their cache at this level -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
