Hi, Mike Thanks for your reply.
On 02/28/2013 03:18 PM, Mike Galbraith wrote: > On Thu, 2013-02-28 at 14:38 +0800, Michael Wang wrote: > >> + /* >> + * current is the only task on rq and it is >> + * going to sleep, current cpu will be a nice >> + * candidate for p to run on. >> + */ > > The sync hint only means it might be going to sleep soon, and even then, > there can still be enough execution overlap to be a win to schedule > cross core. Sched pipe numbers will always be much prettier if you do > wakeup cpu affine, as it's ~100% scheduler and ~100% sync. Hmm.. so it's the comparison between 'cache benefit - execution overlap' and 'latency - execution overlap'? I could not estimate how many latency will be added to wait for current going to sleep (it should be faster than access cold data, isn't it?), but I really like the cache benefit, unless sync doesn't means current is going to sleep every time, but that's the promise of WF_SYNC, isn't it? You may lose > a lot on other stuff if you interpret the hint as gospel truth. Could you please give more details on this point? > > IMHO, sched pipe is a "how fat have I become" benchmark, not "how well > do I perform". The scheduler performs well when it makes more work > happen. Playing ping-pong with yourself is _exercise_, not a job :) That's right, may be I'm using the wrong description, it's the ops/sec which has been doubled, that means 'fat', correct? Regards, Michael Wang > > -Mike > > -- > 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/
