Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Wed, Aug 27, 2014 at 12:43:01PM -0400, Pranith Kumar wrote: > On Wed, Aug 27, 2014 at 12:21 PM, Paul E. McKenney > wrote: > > On Wed, Aug 27, 2014 at 10:13:50AM +0530, Amit Shah wrote: > > >> > >> Yes, this patch helps my case as well. > > > > Very good!!! > > > > Pranith, I can take this

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Wed, Aug 27, 2014 at 12:21 PM, Paul E. McKenney wrote: > On Wed, Aug 27, 2014 at 10:13:50AM +0530, Amit Shah wrote: >> >> Yes, this patch helps my case as well. > > Very good!!! > > Pranith, I can take this patch, but would you be willing to invert > the sense of ->nocb_leader_wake (e.g.,

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Wed, Aug 27, 2014 at 10:13:50AM +0530, Amit Shah wrote: > On (Sat) 23 Aug 2014 [03:43:38], Pranith Kumar wrote: > > On Fri, Aug 22, 2014 at 5:53 PM, Paul E. McKenney > > wrote: > > > > > > Hmmm... Please try replacing the synchronize_rcu() in > > > __sysrq_swap_key_ops() with (say)

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Wed, Aug 27, 2014 at 10:13:50AM +0530, Amit Shah wrote: On (Sat) 23 Aug 2014 [03:43:38], Pranith Kumar wrote: On Fri, Aug 22, 2014 at 5:53 PM, Paul E. McKenney paul...@linux.vnet.ibm.com wrote: Hmmm... Please try replacing the synchronize_rcu() in __sysrq_swap_key_ops() with

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Wed, Aug 27, 2014 at 12:21 PM, Paul E. McKenney paul...@linux.vnet.ibm.com wrote: On Wed, Aug 27, 2014 at 10:13:50AM +0530, Amit Shah wrote: Yes, this patch helps my case as well. Very good!!! Pranith, I can take this patch, but would you be willing to invert the sense of

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Wed, Aug 27, 2014 at 12:43:01PM -0400, Pranith Kumar wrote: On Wed, Aug 27, 2014 at 12:21 PM, Paul E. McKenney paul...@linux.vnet.ibm.com wrote: On Wed, Aug 27, 2014 at 10:13:50AM +0530, Amit Shah wrote: Yes, this patch helps my case as well. Very good!!! Pranith, I can take

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Sat) 23 Aug 2014 [03:43:38], Pranith Kumar wrote: > On Fri, Aug 22, 2014 at 5:53 PM, Paul E. McKenney > wrote: > > > > Hmmm... Please try replacing the synchronize_rcu() in > > __sysrq_swap_key_ops() with (say) schedule_timeout_interruptible(HZ / 10). > > I bet that gets rid of the hang.

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Sat) 23 Aug 2014 [03:43:38], Pranith Kumar wrote: On Fri, Aug 22, 2014 at 5:53 PM, Paul E. McKenney paul...@linux.vnet.ibm.com wrote: Hmmm... Please try replacing the synchronize_rcu() in __sysrq_swap_key_ops() with (say) schedule_timeout_interruptible(HZ / 10). I bet that gets rid

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Sat, Aug 23, 2014 at 11:39:39PM -0400, Pranith Kumar wrote: > On Sat, Aug 23, 2014 at 11:23 PM, Paul E. McKenney > wrote: > > On Sat, Aug 23, 2014 at 08:26:10PM -0400, Pranith Kumar wrote: > >> On Sat, Aug 23, 2014 at 12:51 PM, Paul E. McKenney > >> wrote: > >> > >> > It might well! Another

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Sat, Aug 23, 2014 at 11:39:39PM -0400, Pranith Kumar wrote: On Sat, Aug 23, 2014 at 11:23 PM, Paul E. McKenney paul...@linux.vnet.ibm.com wrote: On Sat, Aug 23, 2014 at 08:26:10PM -0400, Pranith Kumar wrote: On Sat, Aug 23, 2014 at 12:51 PM, Paul E. McKenney paul...@linux.vnet.ibm.com

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Sat, Aug 23, 2014 at 11:23 PM, Paul E. McKenney wrote: > On Sat, Aug 23, 2014 at 08:26:10PM -0400, Pranith Kumar wrote: >> On Sat, Aug 23, 2014 at 12:51 PM, Paul E. McKenney >> wrote: >> >> > It might well! Another possibility is that the early_initcall function >> > doing the

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Sat, Aug 23, 2014 at 08:26:10PM -0400, Pranith Kumar wrote: > On Sat, Aug 23, 2014 at 12:51 PM, Paul E. McKenney > wrote: > > > It might well! Another possibility is that the early_initcall function > > doing the synchronize_rcu() is happening before the early_initcall > > creating the RCU

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Sat, Aug 23, 2014 at 12:51 PM, Paul E. McKenney wrote: > It might well! Another possibility is that the early_initcall function > doing the synchronize_rcu() is happening before the early_initcall > creating the RCU grace-period kthreads. > > Seems like we need to close both holes. Let's

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Sat, Aug 23, 2014 at 03:43:38AM -0400, Pranith Kumar wrote: > On Fri, Aug 22, 2014 at 5:53 PM, Paul E. McKenney > wrote: > > > > Hmmm... Please try replacing the synchronize_rcu() in > > __sysrq_swap_key_ops() with (say) schedule_timeout_interruptible(HZ / 10). > > I bet that gets rid of the

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 22, 2014 at 5:53 PM, Paul E. McKenney wrote: > > Hmmm... Please try replacing the synchronize_rcu() in > __sysrq_swap_key_ops() with (say) schedule_timeout_interruptible(HZ / 10). > I bet that gets rid of the hang. (And also introduces a low-probability > bug, but should be OK for

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 22, 2014 at 5:53 PM, Paul E. McKenney paul...@linux.vnet.ibm.com wrote: Hmmm... Please try replacing the synchronize_rcu() in __sysrq_swap_key_ops() with (say) schedule_timeout_interruptible(HZ / 10). I bet that gets rid of the hang. (And also introduces a low-probability bug,

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Sat, Aug 23, 2014 at 03:43:38AM -0400, Pranith Kumar wrote: On Fri, Aug 22, 2014 at 5:53 PM, Paul E. McKenney paul...@linux.vnet.ibm.com wrote: Hmmm... Please try replacing the synchronize_rcu() in __sysrq_swap_key_ops() with (say) schedule_timeout_interruptible(HZ / 10). I bet that

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Sat, Aug 23, 2014 at 12:51 PM, Paul E. McKenney paul...@linux.vnet.ibm.com wrote: It might well! Another possibility is that the early_initcall function doing the synchronize_rcu() is happening before the early_initcall creating the RCU grace-period kthreads. Seems like we need to close

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Sat, Aug 23, 2014 at 08:26:10PM -0400, Pranith Kumar wrote: On Sat, Aug 23, 2014 at 12:51 PM, Paul E. McKenney paul...@linux.vnet.ibm.com wrote: It might well! Another possibility is that the early_initcall function doing the synchronize_rcu() is happening before the early_initcall

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Sat, Aug 23, 2014 at 11:23 PM, Paul E. McKenney paul...@linux.vnet.ibm.com wrote: On Sat, Aug 23, 2014 at 08:26:10PM -0400, Pranith Kumar wrote: On Sat, Aug 23, 2014 at 12:51 PM, Paul E. McKenney paul...@linux.vnet.ibm.com wrote: It might well! Another possibility is that the

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 22, 2014 at 02:53:44PM -0700, Paul E. McKenney wrote: > On Fri, Aug 22, 2014 at 10:44:05PM +0530, Amit Shah wrote: > > On (Fri) 22 Aug 2014 [07:48:19], Paul E. McKenney wrote: > > > On Fri, Aug 22, 2014 at 06:26:49PM +0530, Amit Shah wrote: > > > > On (Fri) 22 Aug 2014 [18:06:51], Amit

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 22, 2014 at 10:44:05PM +0530, Amit Shah wrote: > On (Fri) 22 Aug 2014 [07:48:19], Paul E. McKenney wrote: > > On Fri, Aug 22, 2014 at 06:26:49PM +0530, Amit Shah wrote: > > > On (Fri) 22 Aug 2014 [18:06:51], Amit Shah wrote: > > > > On (Fri) 22 Aug 2014 [17:54:53], Amit Shah wrote: > >

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 22 Aug 2014 [22:44:05], Amit Shah wrote: > Hm, found it: > > The stall happens in do_initcalls(). > > pm_sysrq_init() is the function that causes the hang. When I #if 0 > the line > > register_sysrq_key('o', _poweroff_op); > > in pm_sysrq_init(), the boot proceeds normally. > >

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 22 Aug 2014 [07:48:19], Paul E. McKenney wrote: > On Fri, Aug 22, 2014 at 06:26:49PM +0530, Amit Shah wrote: > > On (Fri) 22 Aug 2014 [18:06:51], Amit Shah wrote: > > > On (Fri) 22 Aug 2014 [17:54:53], Amit Shah wrote: > > > > On (Mon) 18 Aug 2014 [21:01:49], Paul E. McKenney wrote: > > >

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 22, 2014 at 06:26:49PM +0530, Amit Shah wrote: > On (Fri) 22 Aug 2014 [18:06:51], Amit Shah wrote: > > On (Fri) 22 Aug 2014 [17:54:53], Amit Shah wrote: > > > On (Mon) 18 Aug 2014 [21:01:49], Paul E. McKenney wrote: > > > > > > > The odds are low over the next few days. I am adding

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 22 Aug 2014 [18:06:51], Amit Shah wrote: > On (Fri) 22 Aug 2014 [17:54:53], Amit Shah wrote: > > On (Mon) 18 Aug 2014 [21:01:49], Paul E. McKenney wrote: > > > > > The odds are low over the next few days. I am adding nastier rcutorture > > > testing, however. It would still be very

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 22 Aug 2014 [17:54:53], Amit Shah wrote: > On (Mon) 18 Aug 2014 [21:01:49], Paul E. McKenney wrote: > > > The odds are low over the next few days. I am adding nastier rcutorture > > testing, however. It would still be very good to get debug information > > from your setup. One

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 22 Aug 2014 [17:54:53], Amit Shah wrote: On (Mon) 18 Aug 2014 [21:01:49], Paul E. McKenney wrote: The odds are low over the next few days. I am adding nastier rcutorture testing, however. It would still be very good to get debug information from your setup. One approach would

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 22 Aug 2014 [18:06:51], Amit Shah wrote: On (Fri) 22 Aug 2014 [17:54:53], Amit Shah wrote: On (Mon) 18 Aug 2014 [21:01:49], Paul E. McKenney wrote: The odds are low over the next few days. I am adding nastier rcutorture testing, however. It would still be very good to get

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 22, 2014 at 06:26:49PM +0530, Amit Shah wrote: On (Fri) 22 Aug 2014 [18:06:51], Amit Shah wrote: On (Fri) 22 Aug 2014 [17:54:53], Amit Shah wrote: On (Mon) 18 Aug 2014 [21:01:49], Paul E. McKenney wrote: The odds are low over the next few days. I am adding nastier

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 22 Aug 2014 [07:48:19], Paul E. McKenney wrote: On Fri, Aug 22, 2014 at 06:26:49PM +0530, Amit Shah wrote: On (Fri) 22 Aug 2014 [18:06:51], Amit Shah wrote: On (Fri) 22 Aug 2014 [17:54:53], Amit Shah wrote: On (Mon) 18 Aug 2014 [21:01:49], Paul E. McKenney wrote: The

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 22 Aug 2014 [22:44:05], Amit Shah wrote: Hm, found it: The stall happens in do_initcalls(). pm_sysrq_init() is the function that causes the hang. When I #if 0 the line register_sysrq_key('o', sysrq_poweroff_op); in pm_sysrq_init(), the boot proceeds normally. Now

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 22, 2014 at 10:44:05PM +0530, Amit Shah wrote: On (Fri) 22 Aug 2014 [07:48:19], Paul E. McKenney wrote: On Fri, Aug 22, 2014 at 06:26:49PM +0530, Amit Shah wrote: On (Fri) 22 Aug 2014 [18:06:51], Amit Shah wrote: On (Fri) 22 Aug 2014 [17:54:53], Amit Shah wrote: On (Mon)

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 22, 2014 at 02:53:44PM -0700, Paul E. McKenney wrote: On Fri, Aug 22, 2014 at 10:44:05PM +0530, Amit Shah wrote: On (Fri) 22 Aug 2014 [07:48:19], Paul E. McKenney wrote: On Fri, Aug 22, 2014 at 06:26:49PM +0530, Amit Shah wrote: On (Fri) 22 Aug 2014 [18:06:51], Amit Shah

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Mon, Aug 18, 2014 at 11:23:45PM +0530, Amit Shah wrote: > On (Fri) 15 Aug 2014 [08:04:05], Paul E. McKenney wrote: > > On Fri, Aug 15, 2014 at 10:54:11AM +0530, Amit Shah wrote: > > > On (Wed) 13 Aug 2014 [06:00:49], Paul E. McKenney wrote: > > > > On Wed, Aug 13, 2014 at 11:14:39AM +0530, Amit

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 15 Aug 2014 [08:04:05], Paul E. McKenney wrote: > On Fri, Aug 15, 2014 at 10:54:11AM +0530, Amit Shah wrote: > > On (Wed) 13 Aug 2014 [06:00:49], Paul E. McKenney wrote: > > > On Wed, Aug 13, 2014 at 11:14:39AM +0530, Amit Shah wrote: > > > > On (Tue) 12 Aug 2014 [14:41:51], Paul E.

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 15 Aug 2014 [08:04:05], Paul E. McKenney wrote: On Fri, Aug 15, 2014 at 10:54:11AM +0530, Amit Shah wrote: On (Wed) 13 Aug 2014 [06:00:49], Paul E. McKenney wrote: On Wed, Aug 13, 2014 at 11:14:39AM +0530, Amit Shah wrote: On (Tue) 12 Aug 2014 [14:41:51], Paul E. McKenney wrote:

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Mon, Aug 18, 2014 at 11:23:45PM +0530, Amit Shah wrote: On (Fri) 15 Aug 2014 [08:04:05], Paul E. McKenney wrote: On Fri, Aug 15, 2014 at 10:54:11AM +0530, Amit Shah wrote: On (Wed) 13 Aug 2014 [06:00:49], Paul E. McKenney wrote: On Wed, Aug 13, 2014 at 11:14:39AM +0530, Amit Shah

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 15, 2014 at 10:54:11AM +0530, Amit Shah wrote: > On (Wed) 13 Aug 2014 [06:00:49], Paul E. McKenney wrote: > > On Wed, Aug 13, 2014 at 11:14:39AM +0530, Amit Shah wrote: > > > On (Tue) 12 Aug 2014 [14:41:51], Paul E. McKenney wrote: > > > > On Tue, Aug 12, 2014 at 02:39:36PM -0700, Paul

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 15, 2014 at 10:54:11AM +0530, Amit Shah wrote: On (Wed) 13 Aug 2014 [06:00:49], Paul E. McKenney wrote: On Wed, Aug 13, 2014 at 11:14:39AM +0530, Amit Shah wrote: On (Tue) 12 Aug 2014 [14:41:51], Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 02:39:36PM -0700, Paul E.

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Wed) 13 Aug 2014 [06:00:49], Paul E. McKenney wrote: > On Wed, Aug 13, 2014 at 11:14:39AM +0530, Amit Shah wrote: > > On (Tue) 12 Aug 2014 [14:41:51], Paul E. McKenney wrote: > > > On Tue, Aug 12, 2014 at 02:39:36PM -0700, Paul E. McKenney wrote: > > > > On Tue, Aug 12, 2014 at 09:06:21AM

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Wed) 13 Aug 2014 [06:00:49], Paul E. McKenney wrote: On Wed, Aug 13, 2014 at 11:14:39AM +0530, Amit Shah wrote: On (Tue) 12 Aug 2014 [14:41:51], Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 02:39:36PM -0700, Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 09:06:21AM -0700, Paul E.

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Wed, Aug 13, 2014 at 06:00:49AM -0700, Paul E. McKenney wrote: > On Wed, Aug 13, 2014 at 11:14:39AM +0530, Amit Shah wrote: > > On (Tue) 12 Aug 2014 [14:41:51], Paul E. McKenney wrote: > > > On Tue, Aug 12, 2014 at 02:39:36PM -0700, Paul E. McKenney wrote: > > > > On Tue, Aug 12, 2014 at

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Wed, Aug 13, 2014 at 11:14:39AM +0530, Amit Shah wrote: > On (Tue) 12 Aug 2014 [14:41:51], Paul E. McKenney wrote: > > On Tue, Aug 12, 2014 at 02:39:36PM -0700, Paul E. McKenney wrote: > > > On Tue, Aug 12, 2014 at 09:06:21AM -0700, Paul E. McKenney wrote: > > > > On Tue, Aug 12, 2014 at

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Wed, Aug 13, 2014 at 11:14:39AM +0530, Amit Shah wrote: On (Tue) 12 Aug 2014 [14:41:51], Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 02:39:36PM -0700, Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 09:06:21AM -0700, Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 11:03:21AM

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Wed, Aug 13, 2014 at 06:00:49AM -0700, Paul E. McKenney wrote: On Wed, Aug 13, 2014 at 11:14:39AM +0530, Amit Shah wrote: On (Tue) 12 Aug 2014 [14:41:51], Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 02:39:36PM -0700, Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 09:06:21AM

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Tue) 12 Aug 2014 [14:41:51], Paul E. McKenney wrote: > On Tue, Aug 12, 2014 at 02:39:36PM -0700, Paul E. McKenney wrote: > > On Tue, Aug 12, 2014 at 09:06:21AM -0700, Paul E. McKenney wrote: > > > On Tue, Aug 12, 2014 at 11:03:21AM +0530, Amit Shah wrote: > > > > [ . . . ] > > > > > > I know

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Tue, Aug 12, 2014 at 02:41:51PM -0700, Paul E. McKenney wrote: > On Tue, Aug 12, 2014 at 02:39:36PM -0700, Paul E. McKenney wrote: > > On Tue, Aug 12, 2014 at 09:06:21AM -0700, Paul E. McKenney wrote: > > > On Tue, Aug 12, 2014 at 11:03:21AM +0530, Amit Shah wrote: > > > > [ . . . ] > > > > >

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Tue, Aug 12, 2014 at 02:39:36PM -0700, Paul E. McKenney wrote: > On Tue, Aug 12, 2014 at 09:06:21AM -0700, Paul E. McKenney wrote: > > On Tue, Aug 12, 2014 at 11:03:21AM +0530, Amit Shah wrote: > > [ . . . ] > > > > I know of only virtio-console doing this (via userspace only, > > > though).

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Tue, Aug 12, 2014 at 09:06:21AM -0700, Paul E. McKenney wrote: > On Tue, Aug 12, 2014 at 11:03:21AM +0530, Amit Shah wrote: [ . . . ] > > I know of only virtio-console doing this (via userspace only, > > though). > > As in userspace within the guest? That would not work. The userspace >

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Tue, Aug 12, 2014 at 10:57:26AM +0530, Amit Shah wrote: > On (Mon) 11 Aug 2014 [13:34:21], Paul E. McKenney wrote: > > On Tue, Aug 12, 2014 at 01:48:45AM +0530, Amit Shah wrote: [ . . . ] > > > > In addition "sendkey alt-sysrq-t" at the "(qemu)" prompt dumps all > > > > tasks' > > > >

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Tue, Aug 12, 2014 at 11:03:21AM +0530, Amit Shah wrote: > On (Mon) 11 Aug 2014 [20:45:31], Paul E. McKenney wrote: [ . . . ] > > > That is a bit surprising. Is it possible that the system is OOMing > > > quickly due to grace periods not proceeding? If so, maybe giving the > > > VM more

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Tue, Aug 12, 2014 at 11:03:21AM +0530, Amit Shah wrote: On (Mon) 11 Aug 2014 [20:45:31], Paul E. McKenney wrote: [ . . . ] That is a bit surprising. Is it possible that the system is OOMing quickly due to grace periods not proceeding? If so, maybe giving the VM more memory would

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Tue, Aug 12, 2014 at 10:57:26AM +0530, Amit Shah wrote: On (Mon) 11 Aug 2014 [13:34:21], Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 01:48:45AM +0530, Amit Shah wrote: [ . . . ] In addition sendkey alt-sysrq-t at the (qemu) prompt dumps all tasks' stacks, which would also

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Tue, Aug 12, 2014 at 09:06:21AM -0700, Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 11:03:21AM +0530, Amit Shah wrote: [ . . . ] I know of only virtio-console doing this (via userspace only, though). As in userspace within the guest? That would not work. The userspace that the

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Tue, Aug 12, 2014 at 02:39:36PM -0700, Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 09:06:21AM -0700, Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 11:03:21AM +0530, Amit Shah wrote: [ . . . ] I know of only virtio-console doing this (via userspace only, though). As in

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Tue, Aug 12, 2014 at 02:41:51PM -0700, Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 02:39:36PM -0700, Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 09:06:21AM -0700, Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 11:03:21AM +0530, Amit Shah wrote: [ . . . ] I know of

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Tue) 12 Aug 2014 [14:41:51], Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 02:39:36PM -0700, Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 09:06:21AM -0700, Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 11:03:21AM +0530, Amit Shah wrote: [ . . . ] I know of only

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Mon) 11 Aug 2014 [20:45:31], Paul E. McKenney wrote: > On Mon, Aug 11, 2014 at 01:34:21PM -0700, Paul E. McKenney wrote: > > On Tue, Aug 12, 2014 at 01:48:45AM +0530, Amit Shah wrote: > > > On (Mon) 11 Aug 2014 [13:11:02], Paul E. McKenney wrote: > > > > On Tue, Aug 12, 2014 at 01:11:26AM

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Mon) 11 Aug 2014 [13:34:21], Paul E. McKenney wrote: > On Tue, Aug 12, 2014 at 01:48:45AM +0530, Amit Shah wrote: > > On (Mon) 11 Aug 2014 [13:11:02], Paul E. McKenney wrote: > > > On Tue, Aug 12, 2014 at 01:11:26AM +0530, Amit Shah wrote: > > > > On (Mon) 11 Aug 2014 [09:28:07], Paul E.

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Mon, Aug 11, 2014 at 01:34:21PM -0700, Paul E. McKenney wrote: > On Tue, Aug 12, 2014 at 01:48:45AM +0530, Amit Shah wrote: > > On (Mon) 11 Aug 2014 [13:11:02], Paul E. McKenney wrote: > > > On Tue, Aug 12, 2014 at 01:11:26AM +0530, Amit Shah wrote: > > > > On (Mon) 11 Aug 2014 [09:28:07], Paul

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Tue, Aug 12, 2014 at 01:48:45AM +0530, Amit Shah wrote: > On (Mon) 11 Aug 2014 [13:11:02], Paul E. McKenney wrote: > > On Tue, Aug 12, 2014 at 01:11:26AM +0530, Amit Shah wrote: > > > On (Mon) 11 Aug 2014 [09:28:07], Paul E. McKenney wrote: > > > > On Mon, Aug 11, 2014 at 12:43:08PM +0530, Amit

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Mon) 11 Aug 2014 [13:11:02], Paul E. McKenney wrote: > On Tue, Aug 12, 2014 at 01:11:26AM +0530, Amit Shah wrote: > > On (Mon) 11 Aug 2014 [09:28:07], Paul E. McKenney wrote: > > > On Mon, Aug 11, 2014 at 12:43:08PM +0530, Amit Shah wrote: > > > > On (Fri) 08 Aug 2014 [14:46:48], Paul E.

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Tue, Aug 12, 2014 at 01:11:26AM +0530, Amit Shah wrote: > On (Mon) 11 Aug 2014 [09:28:07], Paul E. McKenney wrote: > > On Mon, Aug 11, 2014 at 12:43:08PM +0530, Amit Shah wrote: > > > On (Fri) 08 Aug 2014 [14:46:48], Paul E. McKenney wrote: > > > > On Fri, Aug 08, 2014 at 02:43:47PM -0700, Paul

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Mon) 11 Aug 2014 [09:28:07], Paul E. McKenney wrote: > On Mon, Aug 11, 2014 at 12:43:08PM +0530, Amit Shah wrote: > > On (Fri) 08 Aug 2014 [14:46:48], Paul E. McKenney wrote: > > > On Fri, Aug 08, 2014 at 02:43:47PM -0700, Paul E. McKenney wrote: > > > > On Sat, Aug 09, 2014 at 12:04:24AM

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Mon, Aug 11, 2014 at 12:43:08PM +0530, Amit Shah wrote: > On (Fri) 08 Aug 2014 [14:46:48], Paul E. McKenney wrote: > > On Fri, Aug 08, 2014 at 02:43:47PM -0700, Paul E. McKenney wrote: > > > On Sat, Aug 09, 2014 at 12:04:24AM +0530, Amit Shah wrote: > > > > On (Fri) 08 Aug 2014 [11:18:35], Paul

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 08 Aug 2014 [14:46:48], Paul E. McKenney wrote: > On Fri, Aug 08, 2014 at 02:43:47PM -0700, Paul E. McKenney wrote: > > On Sat, Aug 09, 2014 at 12:04:24AM +0530, Amit Shah wrote: > > > On (Fri) 08 Aug 2014 [11:18:35], Paul E. McKenney wrote: > > > > [ . . . ] > > > > > > Hmmm... What

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Mon) 11 Aug 2014 [09:28:07], Paul E. McKenney wrote: On Mon, Aug 11, 2014 at 12:43:08PM +0530, Amit Shah wrote: On (Fri) 08 Aug 2014 [14:46:48], Paul E. McKenney wrote: On Fri, Aug 08, 2014 at 02:43:47PM -0700, Paul E. McKenney wrote: On Sat, Aug 09, 2014 at 12:04:24AM +0530, Amit

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Tue, Aug 12, 2014 at 01:11:26AM +0530, Amit Shah wrote: On (Mon) 11 Aug 2014 [09:28:07], Paul E. McKenney wrote: On Mon, Aug 11, 2014 at 12:43:08PM +0530, Amit Shah wrote: On (Fri) 08 Aug 2014 [14:46:48], Paul E. McKenney wrote: On Fri, Aug 08, 2014 at 02:43:47PM -0700, Paul E.

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Mon) 11 Aug 2014 [13:11:02], Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 01:11:26AM +0530, Amit Shah wrote: On (Mon) 11 Aug 2014 [09:28:07], Paul E. McKenney wrote: On Mon, Aug 11, 2014 at 12:43:08PM +0530, Amit Shah wrote: On (Fri) 08 Aug 2014 [14:46:48], Paul E. McKenney wrote:

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Tue, Aug 12, 2014 at 01:48:45AM +0530, Amit Shah wrote: On (Mon) 11 Aug 2014 [13:11:02], Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 01:11:26AM +0530, Amit Shah wrote: On (Mon) 11 Aug 2014 [09:28:07], Paul E. McKenney wrote: On Mon, Aug 11, 2014 at 12:43:08PM +0530, Amit Shah

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Mon, Aug 11, 2014 at 01:34:21PM -0700, Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 01:48:45AM +0530, Amit Shah wrote: On (Mon) 11 Aug 2014 [13:11:02], Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 01:11:26AM +0530, Amit Shah wrote: On (Mon) 11 Aug 2014 [09:28:07], Paul E.

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Mon) 11 Aug 2014 [13:34:21], Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 01:48:45AM +0530, Amit Shah wrote: On (Mon) 11 Aug 2014 [13:11:02], Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 01:11:26AM +0530, Amit Shah wrote: On (Mon) 11 Aug 2014 [09:28:07], Paul E. McKenney wrote:

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Mon) 11 Aug 2014 [20:45:31], Paul E. McKenney wrote: On Mon, Aug 11, 2014 at 01:34:21PM -0700, Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 01:48:45AM +0530, Amit Shah wrote: On (Mon) 11 Aug 2014 [13:11:02], Paul E. McKenney wrote: On Tue, Aug 12, 2014 at 01:11:26AM +0530, Amit

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 08 Aug 2014 [14:46:48], Paul E. McKenney wrote: On Fri, Aug 08, 2014 at 02:43:47PM -0700, Paul E. McKenney wrote: On Sat, Aug 09, 2014 at 12:04:24AM +0530, Amit Shah wrote: On (Fri) 08 Aug 2014 [11:18:35], Paul E. McKenney wrote: [ . . . ] Hmmm... What happens if you

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Mon, Aug 11, 2014 at 12:43:08PM +0530, Amit Shah wrote: On (Fri) 08 Aug 2014 [14:46:48], Paul E. McKenney wrote: On Fri, Aug 08, 2014 at 02:43:47PM -0700, Paul E. McKenney wrote: On Sat, Aug 09, 2014 at 12:04:24AM +0530, Amit Shah wrote: On (Fri) 08 Aug 2014 [11:18:35], Paul E.

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 08, 2014 at 02:43:47PM -0700, Paul E. McKenney wrote: > On Sat, Aug 09, 2014 at 12:04:24AM +0530, Amit Shah wrote: > > On (Fri) 08 Aug 2014 [11:18:35], Paul E. McKenney wrote: > > [ . . . ] > > > > Hmmm... What happens if you boot a7d7a143d0b4cb1914705884ca5c25e322dba693 > > > with

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Sat, Aug 09, 2014 at 12:04:24AM +0530, Amit Shah wrote: > On (Fri) 08 Aug 2014 [11:18:35], Paul E. McKenney wrote: [ . . . ] > > Hmmm... What happens if you boot a7d7a143d0b4cb1914705884ca5c25e322dba693 > > with the kernel parameter "acpi=off"? > > That doesn't change anything - still hangs.

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 08 Aug 2014 [11:18:35], Paul E. McKenney wrote: > On Fri, Aug 08, 2014 at 11:07:10PM +0530, Amit Shah wrote: > > On (Fri) 08 Aug 2014 [09:25:02], Paul E. McKenney wrote: > > > On Fri, Aug 08, 2014 at 02:10:56PM +0530, Amit Shah wrote: > > > > On Friday 11 July 2014 07:05 PM, Paul E.

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 08, 2014 at 11:07:10PM +0530, Amit Shah wrote: > On (Fri) 08 Aug 2014 [09:25:02], Paul E. McKenney wrote: > > On Fri, Aug 08, 2014 at 02:10:56PM +0530, Amit Shah wrote: > > > On Friday 11 July 2014 07:05 PM, Paul E. McKenney wrote: > > > >From: "Paul E. McKenney" > > > > > > > >An

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 08 Aug 2014 [09:25:02], Paul E. McKenney wrote: > On Fri, Aug 08, 2014 at 02:10:56PM +0530, Amit Shah wrote: > > On Friday 11 July 2014 07:05 PM, Paul E. McKenney wrote: > > >From: "Paul E. McKenney" > > > > > >An 80-CPU system with a context-switch-heavy workload can require so > >

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 08, 2014 at 02:10:56PM +0530, Amit Shah wrote: > On Friday 11 July 2014 07:05 PM, Paul E. McKenney wrote: > >From: "Paul E. McKenney" > > > >An 80-CPU system with a context-switch-heavy workload can require so > >many NOCB kthread wakeups that the RCU grace-period kthreads spend

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Friday 11 July 2014 07:05 PM, Paul E. McKenney wrote: From: "Paul E. McKenney" An 80-CPU system with a context-switch-heavy workload can require so many NOCB kthread wakeups that the RCU grace-period kthreads spend several tens of percent of a CPU just awakening things. This clearly will

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Friday 11 July 2014 07:05 PM, Paul E. McKenney wrote: From: Paul E. McKenney paul...@linux.vnet.ibm.com An 80-CPU system with a context-switch-heavy workload can require so many NOCB kthread wakeups that the RCU grace-period kthreads spend several tens of percent of a CPU just awakening

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 08, 2014 at 02:10:56PM +0530, Amit Shah wrote: On Friday 11 July 2014 07:05 PM, Paul E. McKenney wrote: From: Paul E. McKenney paul...@linux.vnet.ibm.com An 80-CPU system with a context-switch-heavy workload can require so many NOCB kthread wakeups that the RCU grace-period

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 08 Aug 2014 [09:25:02], Paul E. McKenney wrote: On Fri, Aug 08, 2014 at 02:10:56PM +0530, Amit Shah wrote: On Friday 11 July 2014 07:05 PM, Paul E. McKenney wrote: From: Paul E. McKenney paul...@linux.vnet.ibm.com An 80-CPU system with a context-switch-heavy workload can require

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 08, 2014 at 11:07:10PM +0530, Amit Shah wrote: On (Fri) 08 Aug 2014 [09:25:02], Paul E. McKenney wrote: On Fri, Aug 08, 2014 at 02:10:56PM +0530, Amit Shah wrote: On Friday 11 July 2014 07:05 PM, Paul E. McKenney wrote: From: Paul E. McKenney paul...@linux.vnet.ibm.com

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On (Fri) 08 Aug 2014 [11:18:35], Paul E. McKenney wrote: On Fri, Aug 08, 2014 at 11:07:10PM +0530, Amit Shah wrote: On (Fri) 08 Aug 2014 [09:25:02], Paul E. McKenney wrote: On Fri, Aug 08, 2014 at 02:10:56PM +0530, Amit Shah wrote: On Friday 11 July 2014 07:05 PM, Paul E. McKenney wrote:

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Sat, Aug 09, 2014 at 12:04:24AM +0530, Amit Shah wrote: On (Fri) 08 Aug 2014 [11:18:35], Paul E. McKenney wrote: [ . . . ] Hmmm... What happens if you boot a7d7a143d0b4cb1914705884ca5c25e322dba693 with the kernel parameter acpi=off? That doesn't change anything - still hangs. I

Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

On Fri, Aug 08, 2014 at 02:43:47PM -0700, Paul E. McKenney wrote: On Sat, Aug 09, 2014 at 12:04:24AM +0530, Amit Shah wrote: On (Fri) 08 Aug 2014 [11:18:35], Paul E. McKenney wrote: [ . . . ] Hmmm... What happens if you boot a7d7a143d0b4cb1914705884ca5c25e322dba693 with the kernel

[PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

From: "Paul E. McKenney" An 80-CPU system with a context-switch-heavy workload can require so many NOCB kthread wakeups that the RCU grace-period kthreads spend several tens of percent of a CPU just awakening things. This clearly will not scale well: If you add enough CPUs, the RCU grace-period

[PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

From: Paul E. McKenney paul...@linux.vnet.ibm.com An 80-CPU system with a context-switch-heavy workload can require so many NOCB kthread wakeups that the RCU grace-period kthreads spend several tens of percent of a CPU just awakening things. This clearly will not scale well: If you add enough