On Mon 2015-07-06 15:59:15, Rafael J. Wysocki wrote: > On Monday, July 06, 2015 01:06:45 PM Pavel Machek wrote: > > On Mon 2015-07-06 01:28:20, Rafael J. Wysocki wrote: > > > On Saturday, July 04, 2015 10:19:55 AM Alan Stern wrote: > > > > On Sat, 4 Jul 2015, Rafael J. Wysocki wrote: > > > > > > > > > The only argument against dropping sys_sync() from the suspend code > > > > > path > > > > > I've seen in this thread that I entirely agree with is that it may > > > > > lead to > > > > > regressions, because we've done it practically forever and it may > > > > > hide latent > > > > > bugs somewhere in block drivers etc. Dropping it, though, is the > > > > > only way > > > > > to see those bugs, if any, and if we want to ever fix them, we need > > > > > to see > > > > > them. That's why I think that it may be a good idea to allow people > > > > > to > > > > > drop it if they are willing to accept some extra risk (via the kernel > > > > > command line, for example). > > > > > > > > I'd be perfectly happy to have the sync selectable at runtime, one way > > > > or another. The three most reasonable options seem to be: > > > > > > > > kernel command line > > > > > > > > sysfs file > > > > > > > > sysctl setting > > > > > > > > The command line is less flexible (it can't be changed after booting). > > > > Either of the other two would be fine with me. > > > > > > We'll probably use a sysfs file (possibly plus a Kconfig option to set the > > > boot time default). > > > > Android people can already do sync-less s2ram using existing > > interface. IMO they should just do it. > > > > In any case, sysfs file + Kconfig is an overkill. We already have too > > many Kconfig options. > > I don't think we can reach a general agreement on what's the *right* approach > with respect to the sys_sync() in the suspend code path, so the only way out > of this situation I can see is to make it configurable.
So first: not having general agreement does not mean we should introduce Kconfig + sysfs file. Second: your proposal of "lets sync if runtime was shorter than xxx" is over complex, but at least should not need Kconfig support... Third: we have ioctl() based interface, and I guess android should use that one; it already has "s2ram without sync" method. > > There's not a single Android phone supported by mainline > > kernel. I'm sure they have bigger problems than Android setting > > default sysfs values... > > But perhaps we'd like to change that? We'd like to, but lets start with the real hard stuff (merging support for Qualcomm chipsets) that is 1000000 LoC+, not with trivial tweaks that would be 1-line change, but we pollute code with Kconfig+sysfs making it 100.. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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/