On 05/28/2013 04:49 PM, Mike Galbraith wrote: > On Tue, 2013-05-28 at 15:22 +0800, Michael Wang wrote: >> On 05/28/2013 02:29 PM, Mike Galbraith wrote: >>> On Tue, 2013-05-28 at 13:02 +0800, Michael Wang wrote: >>>> On 05/22/2013 10:55 PM, Mike Galbraith wrote: >>>>> On Wed, 2013-05-22 at 17:25 +0800, Michael Wang wrote: >>>>> >>>>>> 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 :) >>>>> >>>>> On a 4 socket 40 core (+SMT) box, hackbench wasn't too happy. >>>> >>>> I've done more test and now I got the reason of regression... >>>> >>>> The writer and reader in hackbench is N:N, prev writer will write all >>>> the fd then switch to next writer and repeat the same work, so it's >>>> impossible to setup the buddy relationship by just record the last one, >>>> and we have to record all the waker/wakee in history, but that means >>>> unacceptable memory overhead... >>> >>> Yeah, that's why I was thinking we'd need a dinky/fast as hell FIFO of >>> tokens or such to bind waker/wakee more or less reliably. Making such a >>> scheme cheap enough could be hard. >>> >>>> So this buddy idea seems to be bad... >>>> >>>> I think a better way may should be allowing pull in most time, but >>>> filter the very bad cases carefully. >>> >>> Any way that is cheap, and fairly accurately recognizes when we're being >>> stupid will help. First and foremost, it has to be dirt cheap :) >>> >>>> For workload like pgbench, we actually just need to avoid pull if that >>>> will damage the 'mother' thread, which is busy and be relied by many >>>> 'child'. >>> >>> Yeah, 'mom' is the key player. If we can cheaply recognize mom, that >>> should get us a generic improvement. Not as good as being able to >>> recognize the size of her+brood as size changes, but better anyway. >> >> That's right, I'm trying to rely on the frequency of a task switching >> it's wakee in the new idea, it's really cheap and somewhat reliable, I >> appreciate if you could pay an eye on the new patch and let me know you >> opinion :) > > I'll feed it to my 40 core box, hopefully soon.
Thanks for that, wish it taste delicious ;-) 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/
