-- On Tue, 2 Oct 2007, Clark Williams wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Steven Rostedt wrote: > > That last change (new Preempt RCU) is highly experimental!!! > > We are currently testing it now, although it has been through some > > minor tests already, we haven't declared it stable yet. > > > > This new implementation might shave your cat, eat your dog and > > make your children miss the bus and be late for school. > > You have been warned! As is said many times on this list > > "If it breaks, you get to keep the pieces". So don't come crying > > to us if something terrible happens, but please let us know > > so that we can try to fix what broke. > > > > That said, please test it as much as possible. We are happy with > > the new implementation, but it's still young, and we want to > > shake out the problems so it can be pushed up into mainline. > > > > Luckily, I'm currently catless, dogless and childless, so no harm done :) Great! So you are the perfect tester for us! > > I'm running this kernel on a Thinkpad T60 (Core2 Duo, x86_64). When I suspended to > RAM and then resumed, my syslog window started scrolling the following: > > Oct 2 19:45:46 localhost kernel: [<ffffffff8020ac90>] mwait_idle+0x0/0x5f > Oct 2 19:45:46 localhost kernel: [<ffffffff8020ac05>] cpu_idle+0xc7/0xee > Oct 2 19:45:46 localhost kernel: [<ffffffff8021c6f3>] start_secondary+0x2e4/0x2f5 > Oct 2 19:45:46 localhost kernel: > Oct 2 19:45:46 localhost kernel: WARNING: at include/linux/rcupreempt.h:91 > rcu_enter_nohz() > Oct 2 19:45:46 localhost kernel: > Oct 2 19:45:46 localhost kernel: Call Trace: > Oct 2 19:45:46 localhost kernel: [<ffffffff80254a0b>] > tick_nohz_stop_sched_tick+0x1c6/0x2aa > Oct 2 19:45:46 localhost kernel: [<ffffffff8020ac90>] mwait_idle+0x0/0x5f > Oct 2 19:45:46 localhost gpm[2095]: *** err [gpm.c(529)]: > Oct 2 19:45:46 localhost gpm[2095]: select(): Interrupted system call > Oct 2 19:45:46 localhost kernel: [<ffffffff8020ab80>] cpu_idle+0x42/0xee > Oct 2 19:45:46 localhost kernel: [<ffffffff8021c6f3>] start_secondary+0x2e4/0x2f5 > Oct 2 19:45:46 localhost kernel: > Oct 2 19:45:46 localhost kernel: WARNING: at include/linux/rcupreempt.h:99 > rcu_exit_nohz() grmbl grmbl!!! We are missing a match somewhere. Most likely in the suspend or resume code. It's expected that if a CPU is idle with no ticks then the dynticks_progress_counter is even, otherwise it is odd. This check tells us that, in your case, this isn't the case. Which _is_ bad, and I wouldn't run it too long that way. It means that you can be getting false RCU grace period ends, which is not a good thing. I could put a hack in that fixes the issue when detected, and still prints out a warning. I'll do that for now, until we find the problem area. I think the first warning probably had the want that corrupted us, and then we got flooded with warnings because we never fixed the situation. Patch coming soon. -- Steve > > Ad infinitum. Not sure what you're looking for to be cleared in the enter and exit > functions, but it doesn't look like it's happening after a resume. Didn't seem to > affect the behavior of the kernel, since the network came up and I was able to > function normally (or as normally as I can function). I'd reboot if I were you ;-) -- Steve - To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
