On 05/22/2013 04:49 PM, Peter Zijlstra wrote: [snip] >> >> CC: Ingo Molnar <mi...@kernel.org> >> CC: Peter Zijlstra <pet...@infradead.org> >> CC: Mike Galbraith <efa...@gmx.de> >> CC: Alex Shi <alex....@intel.com> >> Suggested-by: Peter Zijlstra <pet...@infradead.org> >> Signed-off-by: Michael Wang <wang...@linux.vnet.ibm.com>
Thanks for your reply, I've looking forward it for a long time... > > So I utterly hate this patch. I hate it worse than your initial buddy > patch :/ Then we nuke it, and figure out the better one ;-) > > And I know its got a Suggested-by there; but that was when you led me to > believe that wake_affine() itself was expensive to run; its not, its the > result of those runs you don't like. Both are the reason, it's just the game between gain & lost & cost, your suggestion definitely is a good choice, otherwise I won't pay time on it, and I will call it's the best one if we are searching for a quick fix. > > While we have a ton (too many to be sure) scheduler tunables, users > shouldn't ever need to actually touch those. Its just that every time we > have to make a random choice its as easy to make it a debug knob as to > hardcode it. > > The problem with this patch is that users _have_ to frob knobs and while > doing so potentially wreck other workloads. > > To make it worse, the knob isn't anything fundamental, its a random > hack. So we discard. > > So I would really either improve the smarts of wake_affine, with for > example your wake buddy relation thing (and simply exempt [Soft]IRQs) or > kill wake_affine and be done with it. No kill...we show mercy, I will back to the wakeup-buddy and let's forgot the IRQ case temporarily unless some regression report appear. > > Either avenue has the risk of regressing some workload, but at least > when that happens (and people report it) we'll have a counter-example to > learn from and incorporate. I've not test the hackbench with wakeup-buddy before, will do it this time, I suppose the 15% illegal income will suffered, anyway, it's illegal :) Regards, Michael Wang > -- > 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/ > -- 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/
