On Saturday 19 December 2009, Dmitry Torokhov wrote: > On Fri, Dec 18, 2009 at 11:43:29PM +0100, Rafael J. Wysocki wrote: > > On Wednesday 16 December 2009, Dmitry Torokhov wrote: > > > 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.) > > > > The problem apparently is that the i8042 suspend/resume is synchronous. > > > > Do you think it's safe to mark it as asynchronous? > > > > Umm.. there lie dragons. There is an implicit relationship between i8042 > and PNP/ACPI devices representing keyboard and mouse ports, and I am not > sure how happy i8042 (and most importantly the BIOS) will be if they get > shut down before i8042. Also there is EC which is in theory independent > but in practice not so much. I see. Is this possible to identify ACPI devices that should wait for the i8042 suspend and that should be waited for by it on resume? Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
