Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-10-01 Thread Paul E. McKenney
On Mon, Oct 01, 2012 at 10:55:11AM +0200, Linus Walleij wrote: > On Sat, Sep 22, 2012 at 11:59 PM, Paul E. McKenney > wrote: > > > rcu: Fix day-one dyntick-idle stall-warning bug > > As mentioned in another thread this solves the same problem for ux500. > Reported/Tested-by: Linus Walleij > >

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-10-01 Thread Linus Walleij
On Sat, Sep 22, 2012 at 11:59 PM, Paul E. McKenney wrote: > rcu: Fix day-one dyntick-idle stall-warning bug As mentioned in another thread this solves the same problem for ux500. Reported/Tested-by: Linus Walleij But now it appears that this commit didn't make it into v3.6 so it definately nee

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-24 Thread Paul E. McKenney
On Mon, Sep 24, 2012 at 09:54:00PM +, Paul Walmsley wrote: > On Sat, 22 Sep 2012, Paul E. McKenney wrote: > > > On Sat, Sep 22, 2012 at 10:20:19PM +, Paul Walmsley wrote: > > > On Sat, 22 Sep 2012, Paul E. McKenney wrote: > > > > > > > This thing has been in the kernel since about 2004, no

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-24 Thread Paul Walmsley
On Sat, 22 Sep 2012, Paul E. McKenney wrote: > On Sat, Sep 22, 2012 at 10:20:19PM +, Paul Walmsley wrote: > > On Sat, 22 Sep 2012, Paul E. McKenney wrote: > > > > > This thing has been in the kernel since about 2004, not sure why you > > > didn't hit it earlier. > > > > One other data point

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-24 Thread Paul E. McKenney
On Mon, Sep 24, 2012 at 03:11:34PM +0530, Shilimkar, Santosh wrote: > On Sun, Sep 23, 2012 at 3:29 AM, Paul E. McKenney > wrote: > > On Sat, Sep 22, 2012 at 01:10:43PM -0700, Paul E. McKenney wrote: > >> On Sat, Sep 22, 2012 at 06:42:08PM +, Paul Walmsley wrote: > >> > On Fri, 21 Sep 2012, Pau

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-24 Thread Shilimkar, Santosh
On Sun, Sep 23, 2012 at 3:29 AM, Paul E. McKenney wrote: > On Sat, Sep 22, 2012 at 01:10:43PM -0700, Paul E. McKenney wrote: >> On Sat, Sep 22, 2012 at 06:42:08PM +, Paul Walmsley wrote: >> > On Fri, 21 Sep 2012, Paul E. McKenney wrote: [...] > > And here is a patch. I am still having troub

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-23 Thread Paul E. McKenney
On Sun, Sep 23, 2012 at 07:55:50AM +, Paul Walmsley wrote: > On Sat, 22 Sep 2012, Paul E. McKenney wrote: > > > On Sat, Sep 22, 2012 at 10:25:59PM +, Paul Walmsley wrote: > > > > > The recent tests here have been on Pandaboard, which is dual-CPU, but my > > > recollection is that I also

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-23 Thread Paul Walmsley
On Sat, 22 Sep 2012, Paul E. McKenney wrote: > On Sat, Sep 22, 2012 at 10:25:59PM +, Paul Walmsley wrote: > > > The recent tests here have been on Pandaboard, which is dual-CPU, but my > > recollection is that I also observed the warnings on a single-core > > Beagleboard. Will re-test. >

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-22 Thread Paul Walmsley
On Sat, 22 Sep 2012, Paul E. McKenney wrote: > Very cool, thank you for your testing efforts!!! You're welcome. > May I apply your Tested-by to this patch? Please do: Tested-by: Paul Walmsley # OMAP4430 Am testing on OMAP3730 (single-core) now. - Paul -- To unsubscribe from this list: sen

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-22 Thread Paul E. McKenney
On Sun, Sep 23, 2012 at 01:42:10AM +, Paul Walmsley wrote: > Hi Paul > > On Sat, 22 Sep 2012, Paul Walmsley wrote: > > > On Sat, 22 Sep 2012, Paul E. McKenney wrote: > > > > > And here is a patch. I am still having trouble reproducing the problem, > > > but figured that I should avoid seria

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-22 Thread Paul Walmsley
Hi Paul On Sat, 22 Sep 2012, Paul Walmsley wrote: > On Sat, 22 Sep 2012, Paul E. McKenney wrote: > > > And here is a patch. I am still having trouble reproducing the problem, > > but figured that I should avoid serializing things. > > Thanks, testing this now on v3.6-rc6. Looks like you solve

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-22 Thread Paul E. McKenney
On Sat, Sep 22, 2012 at 10:20:19PM +, Paul Walmsley wrote: > Hi Paul > > On Sat, 22 Sep 2012, Paul E. McKenney wrote: > > > Strangely enough, I believe that I have inadvertently fixed this in > > my -rcu tree: > > > > git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/ne

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-22 Thread Paul E. McKenney
On Sat, Sep 22, 2012 at 10:25:59PM +, Paul Walmsley wrote: > On Sat, 22 Sep 2012, Paul E. McKenney wrote: > > > And here is a patch. I am still having trouble reproducing the problem, > > but figured that I should avoid serializing things. > > Thanks, testing this now on v3.6-rc6. Very cool

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-22 Thread Paul Walmsley
On Sat, 22 Sep 2012, Paul E. McKenney wrote: > And here is a patch. I am still having trouble reproducing the problem, > but figured that I should avoid serializing things. Thanks, testing this now on v3.6-rc6. One question though about the patch description: > All this begs the question of e

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-22 Thread Paul Walmsley
Hi Paul On Sat, 22 Sep 2012, Paul E. McKenney wrote: > Strangely enough, I believe that I have inadvertently fixed this in > my -rcu tree: > > git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/next > > Nevertheless, if you get a chance to try it, I would be interested to >

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-22 Thread Paul E. McKenney
On Sat, Sep 22, 2012 at 01:10:43PM -0700, Paul E. McKenney wrote: > On Sat, Sep 22, 2012 at 06:42:08PM +, Paul Walmsley wrote: > > On Fri, 21 Sep 2012, Paul E. McKenney wrote: > > > > > Could you please point me to a recipe for creating a minimal userspace? > > > Just in case it is the userspa

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-22 Thread Paul E. McKenney
On Sat, Sep 22, 2012 at 06:16:15PM +, Paul Walmsley wrote: > Hi Paul > > On Fri, 21 Sep 2012, Paul E. McKenney wrote: > > > I am wondering if your system somehow figured out how to start a grace > > period that had no RCU callbacks waiting for it. If that happened, > > then a CONFIG_NO_HZ=y

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-22 Thread Paul E. McKenney
On Sat, Sep 22, 2012 at 06:42:08PM +, Paul Walmsley wrote: > On Fri, 21 Sep 2012, Paul E. McKenney wrote: > > > Could you please point me to a recipe for creating a minimal userspace? > > Just in case it is the userspac erather than the architecture/hardware > > that makes the difference. > >

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-22 Thread Paul Walmsley
On Fri, 21 Sep 2012, Paul E. McKenney wrote: > Could you please point me to a recipe for creating a minimal userspace? > Just in case it is the userspac erather than the architecture/hardware > that makes the difference. Tony's suggestion is pretty good. Note that there may also be differences

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-22 Thread Paul Walmsley
Hi Paul On Fri, 21 Sep 2012, Paul E. McKenney wrote: > I am wondering if your system somehow figured out how to start a grace > period that had no RCU callbacks waiting for it. If that happened, > then a CONFIG_NO_HZ=y system could in theory get into a state where all > CPUs are in dyntick-idle

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-22 Thread Paul E. McKenney
On Sat, Sep 22, 2012 at 05:45:12PM +0200, Frederic Weisbecker wrote: > 2012/9/22 Paul E. McKenney : > > On Fri, Sep 21, 2012 at 01:31:49PM -0700, Tony Lindgren wrote: > >> * Paul E. McKenney [120921 12:58]: > >> > > >> > Just to make sure I understand the combinations: > >> > > >> > o All stalls

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-22 Thread Frederic Weisbecker
2012/9/22 Paul E. McKenney : > On Fri, Sep 21, 2012 at 01:31:49PM -0700, Tony Lindgren wrote: >> * Paul E. McKenney [120921 12:58]: >> > >> > Just to make sure I understand the combinations: >> > >> > o All stalls have happened when running a minimal userspace. >> > o CONFIG_NO_HZ=n suppresses

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-21 Thread Paul E. McKenney
On Fri, Sep 21, 2012 at 10:41:14PM +, Paul Walmsley wrote: > On Fri, 21 Sep 2012, Paul E. McKenney wrote: > > > On Fri, Sep 21, 2012 at 05:47:31PM +, Paul Walmsley wrote: > > > > > I built an OMAP kernel from Linus' commit > > > 4651afbbae968772efd6dc4ba461cba9b49bb9d8 ("Merge branch 'for

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-21 Thread Paul Walmsley
On Fri, 21 Sep 2012, Paul E. McKenney wrote: > On Fri, Sep 21, 2012 at 05:47:31PM +, Paul Walmsley wrote: > > > I built an OMAP kernel from Linus' commit > > 4651afbbae968772efd6dc4ba461cba9b49bb9d8 ("Merge branch 'for-3.6-fixes' of > > git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq").

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-21 Thread Paul E. McKenney
On Fri, Sep 21, 2012 at 12:57:17PM -0700, Paul E. McKenney wrote: > On Fri, Sep 21, 2012 at 07:11:14PM +, Paul Walmsley wrote: > > On Fri, 21 Sep 2012, Paul E. McKenney wrote: [ . . . ] > > > I may take your advice of remote access to a Panda board, though that > > > is likely to take a bit o

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-21 Thread Paul E. McKenney
On Fri, Sep 21, 2012 at 01:31:49PM -0700, Tony Lindgren wrote: > * Paul E. McKenney [120921 12:58]: > > > > Just to make sure I understand the combinations: > > > > o All stalls have happened when running a minimal userspace. > > o CONFIG_NO_HZ=n suppresses the stalls. > > o CONFIG_RCU_FAS

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-21 Thread Paul E. McKenney
On Fri, Sep 21, 2012 at 05:47:31PM +, Paul Walmsley wrote: > Hi Paul > > On Thu, 20 Sep 2012, Paul Walmsley wrote: > > > On Thu, 20 Sep 2012, Paul E. McKenney wrote: > > > > > Paul Walmsley, please let me know if the config below doesn't clear things > > > up for you or if there is some reaso

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-21 Thread Tony Lindgren
* Paul E. McKenney [120921 12:58]: > > Just to make sure I understand the combinations: > > o All stalls have happened when running a minimal userspace. > o CONFIG_NO_HZ=n suppresses the stalls. > o CONFIG_RCU_FAST_NO_HZ (which depends on CONFIG_NO_HZ=y) has > no observable eff

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-21 Thread Paul E. McKenney
On Fri, Sep 21, 2012 at 07:11:14PM +, Paul Walmsley wrote: > On Fri, 21 Sep 2012, Paul E. McKenney wrote: > > > On Fri, Sep 21, 2012 at 06:08:59PM +, Paul Walmsley wrote: > > > > > As far as I know, our only idle entry point is in > > > arch/arm/common/process.c:cpu_idle(). > > > > In m

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-21 Thread Paul Walmsley
On Fri, 21 Sep 2012, Paul E. McKenney wrote: > On Fri, Sep 21, 2012 at 06:08:59PM +, Paul Walmsley wrote: > > > As far as I know, our only idle entry point is in > > arch/arm/common/process.c:cpu_idle(). > > In mainline, this is arch/arm/kernel/process.c, correct? Indeed; sorry about that,

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-21 Thread Paul Walmsley
Hi Just did a test with CONFIG_NO_HZ=n, and no rcu_sched stall messages appeared for 60 minutes. Following is the diff from omap2plus_defconfig. - Paul --- .config 2012-09-21 12:51:19.114938954 -0600 +++ .testconfig 2012-09-21 12:51:15.686926318 -0600 @@ -69,7 +69,7 @@ # Timers subsystem

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-21 Thread Paul E. McKenney
On Fri, Sep 21, 2012 at 06:08:59PM +, Paul Walmsley wrote: > cc Frederic Weisbecker - context is here: > >http://marc.info/?l=linux-kernel&m=134749030206016&w=2 > > On Thu, 20 Sep 2012, Paul E. McKenney wrote: > > > Fair point. I am wondering whether there is some path into the idle >

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-21 Thread Paul Walmsley
cc Frederic Weisbecker - context is here: http://marc.info/?l=linux-kernel&m=134749030206016&w=2 On Thu, 20 Sep 2012, Paul E. McKenney wrote: > Fair point. I am wondering whether there is some path into the idle > loop that somehow avoids telling RCU that the CPU has in face entered > idle.

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-21 Thread Paul Walmsley
On Fri, 21 Sep 2012, Paul Walmsley wrote: > The config used was 'omap2plus_defconfig', and enabled CONFIG_CPU_IDLE > by hand. One other thing I forgot to mention - CONFIG_RCU_CPU_STALL_INFO was enabled by hand also. Below is the diff between omap2plus_defconfig and the config that was used h

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-21 Thread Paul Walmsley
Hi Paul On Thu, 20 Sep 2012, Paul Walmsley wrote: > On Thu, 20 Sep 2012, Paul E. McKenney wrote: > > > Paul Walmsley, please let me know if the config below doesn't clear things > > up for you or if there is some reason why this config is infeasible. > > Will certainly test it here once things s

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-20 Thread Paul E. McKenney
On Thu, Sep 20, 2012 at 10:47:25PM +, Paul Walmsley wrote: > On Thu, 20 Sep 2012, Paul E. McKenney wrote: > > > On Thu, Sep 20, 2012 at 09:49:13PM +, Bruce, Becky wrote: > > > > > OK, people, you can stop heckling me about "sent from my iPhone" - I'm in > > > the wilds of rural Louisiana

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-20 Thread Paul Walmsley
On Thu, 20 Sep 2012, Paul E. McKenney wrote: > On Thu, Sep 20, 2012 at 09:49:13PM +, Bruce, Becky wrote: > > > OK, people, you can stop heckling me about "sent from my iPhone" - I'm in > > the wilds of rural Louisiana with really bad internet service and was > > trying to work on my phone (b

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-20 Thread Paul E. McKenney
On Thu, Sep 20, 2012 at 09:49:13PM +, Bruce, Becky wrote: > > On Sep 20, 2012, at 2:56 AM, Paul Walmsley wrote: > > > Hi, > > > > On Wed, 19 Sep 2012, Paul E. McKenney wrote: > > > >> On Thu, Sep 13, 2012 at 06:52:10PM +, Paul Walmsley wrote: > >> > >>> On Wed, 12 Sep 2012, Paul E. McK

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-20 Thread Bruce, Becky
On Sep 20, 2012, at 2:56 AM, Paul Walmsley wrote: > Hi, > > On Wed, 19 Sep 2012, Paul E. McKenney wrote: > >> On Thu, Sep 13, 2012 at 06:52:10PM +, Paul Walmsley wrote: >> >>> On Wed, 12 Sep 2012, Paul E. McKenney wrote: >> Subodh Nijsure (also CCed) reported something that might be

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-20 Thread Bruce, Becky
I'll give it a try on my panda later today. B Sent from my iPhone On Sep 20, 2012, at 2:56 AM, "Paul Walmsley" wrote: > Hi, > > On Wed, 19 Sep 2012, Paul E. McKenney wrote: > >> On Thu, Sep 13, 2012 at 06:52:10PM +, Paul Walmsley wrote: >> >>> On Wed, 12 Sep 2012, Paul E. McKenney wrote

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-20 Thread Paul Walmsley
Hi, On Wed, 19 Sep 2012, Paul E. McKenney wrote: > On Thu, Sep 13, 2012 at 06:52:10PM +, Paul Walmsley wrote: > > > On Wed, 12 Sep 2012, Paul E. McKenney wrote: > > > > Subodh Nijsure (also CCed) reported something that might be similar on > > > ARM, and also reported that setting the foll

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-19 Thread Paul E. McKenney
On Thu, Sep 13, 2012 at 06:52:10PM +, Paul Walmsley wrote: > Hi Paul, > > thanks for the reply, > > On Wed, 12 Sep 2012, Paul E. McKenney wrote: > > > Interesting. I am assuming that the interrupt in the stack below came > > from idle, if not, please let me know what. > > According to the

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-13 Thread Paul Walmsley
Hi Paul, thanks for the reply, On Wed, 12 Sep 2012, Paul E. McKenney wrote: > Interesting. I am assuming that the interrupt in the stack below came > from idle, if not, please let me know what. According to the exception stack section in the original traceback, it appears that the serial inter

Re: rcu self-detected stall messages on OMAP3, 4 boards

2012-09-12 Thread Paul E. McKenney
On Wed, Sep 12, 2012 at 10:51:30PM +, Paul Walmsley wrote: > > Hi Paul > > Recently several of us have been seeing "INFO: rcu_sched self-detected > stall on CPU { 0} (t=20611 jiffies)" stack tracebacks on various OMAP3 > and 4 board. > > I only noticed it during v3.6-rc3, but I suspect it's

rcu self-detected stall messages on OMAP3, 4 boards

2012-09-12 Thread Paul Walmsley
Hi Paul Recently several of us have been seeing "INFO: rcu_sched self-detected stall on CPU { 0} (t=20611 jiffies)" stack tracebacks on various OMAP3 and 4 board. I only noticed it during v3.6-rc3, but I suspect it's been happening for users at least since May: http://www.mail-archive.com/linu