On 2013-06-08 18:54, Rafael J. Wysocki wrote: > On Saturday, June 08, 2013 10:37:18 AM Yanmin Zhang wrote: >> On Sat, 2013-06-08 at 03:52 +0200, Rafael J. Wysocki wrote: >>> On Saturday, June 08, 2013 09:36:03 AM Yanmin Zhang wrote: >>>> On Sat, 2013-06-08 at 03:30 +0200, Rafael J. Wysocki wrote: >>>>> On Friday, June 07, 2013 06:16:25 PM Greg KH wrote: >>>>>> On Sat, Jun 08, 2013 at 08:42:12AM +0800, Yanmin Zhang wrote: >>>>>>> On Fri, 2013-06-07 at 12:36 +0200, Rafael J. Wysocki wrote: >>>>>>>> On Friday, June 07, 2013 04:20:30 PM shuox....@intel.com wrote: >>>>>>>>> dpm_run_callback is used in other stages of power states changing. >>>>>>>>> It provides debug info message and time measurement when call these >>>>>>>>> callback. We also want to benefit ->prepare and ->complete. >>>>>>>>> >>>>>>>>> [PATCH 1/2] PM: use dpm_run_callback in device_prepare >>>>>>>>> [PATCH 2/2] PM: add dpm_run_callback_void and use it in >>>>>>>>> device_complete >>>>>>>> >>>>>>>> Is this an "Oh, why don't we do that?" series, or is it useful for >>>>>>>> anything >>>>>>>> in practice? I'm asking, because we haven't added that stuff to start >>>>>>>> with >>>>>>>> since we didn't see why it would be useful to anyone. >>>>>>>> >>>>>>>> And while patch [1/2] reduces the code size (by 1 line), so I can see >>>>>>>> some >>>>>>>> (tiny) benefit from applying it, patch [2/2] adds more code and is >>>>>>>> there any >>>>>>>> paractical reason? >>>>>>> Sometimes, suspend-to-ram path spends too much time (either suspend >>>>>>> slowly >>>>>>> or wakeup slowly) and we need optimize it. >>>>>>> With the 2 patches, we could collect initcall_debug printk info and >>>>>>> manually >>>>>>> check what prepare/complete callbacks consume too much time. >>>>>> >>>>>> But initcall information is for initialization stuff, not suspend/resume >>>>>> things, right? Doesn't the existing tools for parsing this choke if it >>>>>> sees the information at suspend/resume time? >>>>> >>>>> We've been using that for suspend/resume for quite some time too, but not >>>>> for the prepare/complete phases (because we still believe that's not >>>>> really >>>>> useful for them). >>>>> >>>>> Well, I'll be handling patches changing code under drivers/base/power, >>>>> I promise. :-) >>>>> >>>>> I've been doing that for quite a few years now ... >>>> Yes, indeed. Power is one of the most important features on embedded >>>> devices. >>>> Lots of smart phones don't really go through the full cycles of >>>> suspend-to-ram. >>>> We are following the full steps of the suspend. >>> >>> But if you go through the code, you'll see that alomost no drivers actually >>> implemet .prepare() and .complete(). Some subsystems do, but they really >>> don't >>> take too much time to execute. Which means that your patches with >>> initcall_debug will add quite a pile of useless garbage to the kernel log >> Does that mean we need add more log levels around such info instead of just >> having or >> not having? > > Since we don't have any code in the tree that causes problems those patches > are > supposed to catch, I don't see why we need them in the tree. Would it be > viable to keep them out of the tree for the time being and re-submit once > there is real need?
It's OK with me. I will keep them in my debug tree. Thanks all. Shuo -- 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/
