On Wed, Dec 16, 2009 at 03:11:05AM +0100, Rafael J. Wysocki wrote: > On Tuesday 15 December 2009, Linus Torvalds wrote: > > > > On Tue, 15 Dec 2009, Rafael J. Wysocki wrote: > > > > > > > > Give a real example that matters. > > > > > > I'll try. Let -> denote child-parent relationships and assume dpm_list looks > > > like this: > > > > No. > > > > I mean something real - something like > > > > - if you run on a non-PC with two USB buses behind non-PCI controllers. > > > > - device xyz. > > > > > If this applies to _resume_ only, then I agree, but the Arjan's data clearly > > > show that serio devices take much more time to suspend than USB. > > > > I mean in general - something where you actually have hard data that some > > device really needs anythign more than my one-liner, and really _needs_ > > some complex infrastructure. > > > > Not "let's imagine a case like xyz". > > As I said I would, I made some measurements. > > I measured the total time of suspending and resuming devices as shown by the > code added by this patch: > http://git.kernel.org/?p=linux/kernel/git/rafael/suspend-2.6.git;a=commitdiff_plain;h=c1b8fc0a8bff7707c10f31f3d26bfa88e18ccd94;hp=087dbf5f079f1b55cbd3964c9ce71268473d5b67 > on two boxes, HP nx6325 and MSI Wind U100 (hardware-wise they are quite > different and the HP was running 64-bit kernel and user space). > > I took four cases into consideration: > (1) synchronous suspend and resume (/sys/power/pm_async = 0) > (2) asynchronous suspend and resume as introduced by the async branch at: > http://git.kernel.org/?p=linux/kernel/git/rafael/suspend-2.6.git;a=shortlog;h=refs/heads/async > (3) asynchronous suspend and resume like in (2), but with your one-liner setting > the power.async_suspend flag for PCI bridges on top > (4) asynchronous suspend and resume like in (2), but with an extra patch that > is appended on top > > For those tests I set power.async_suspend for all USB devices, all serio input > devices, the ACPI battery and the USB PCI controllers (to see the impact of the > one-liner, if any). > > I carried out 5 consecutive suspend-resume cycles (started from under X) on > each box in each case, and the raw data are here (all times in milliseconds): > http://www.sisk.pl/kernel/data/async-suspend.pdf > > The summarized data are below (the "big" numbers are averages and the +/- > numbers are standard deviations, all in milliseconds): > > HP nx6325 MSI Wind U100 > > sync suspend 1482 (+/- 40) 1180 (+/- 24) > sync resume 2955 (+/- 2) 3597 (+/- 25) > > async suspend 1553 (+/- 49) 1177 (+/- 32) > async resume 2692 (+/- 326) 3556 (+/- 33) > > async+one-liner suspend 1600 (+/- 39) 1212 (+/- 41) > async+one-liner resume 2692 (+/- 324) 3579 (+/- 24) > > async+extra suspend 1496 (+/- 37) 1217 (+/- 38) > async+extra resume 1859 (+/- 114) 1923 (+/- 35) > > So, in my opinion, with the above set of "async" devices, it doesn't > make sense to do async suspend at all, because the sync suspend is actually > the fastest on both machines. I think the async suspend is not asynchronous enough then - what kind of time do you get if you simply comment out call to psmouse_reset() in drivers/input/mouse/psmouse-base.c:psmouse_cleanup()? (Just for testing purposes only, I don't think we want to do that by default.) -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html