Re: [PATCH 01/13] rcu/nocb: Fix potential missed nocb_timer rearm

2021-03-03 Thread Neeraj Upadhyay
Hi, On 3/2/2021 11:47 PM, Paul E. McKenney wrote: On Tue, Mar 02, 2021 at 01:34:44PM +0100, Frederic Weisbecker wrote: On Mon, Mar 01, 2021 at 05:48:29PM -0800, Paul E. McKenney wrote: On Wed, Feb 24, 2021 at 11:06:06PM +0100, Frederic Weisbecker wrote: On Wed, Feb 24, 2021 at 10:37:09AM

Re: [PATCH 01/13] rcu/nocb: Fix potential missed nocb_timer rearm

2021-03-03 Thread Frederic Weisbecker
On Tue, Mar 02, 2021 at 06:06:43PM -0800, Paul E. McKenney wrote: > On Wed, Mar 03, 2021 at 02:35:33AM +0100, Frederic Weisbecker wrote: > > On Tue, Mar 02, 2021 at 10:17:29AM -0800, Paul E. McKenney wrote: > > > On Tue, Mar 02, 2021 at 01:34:44PM +0100, Frederic Weisbecker wrote: > > > > > > OK,

Re: [PATCH 01/13] rcu/nocb: Fix potential missed nocb_timer rearm

2021-03-03 Thread Paul E. McKenney
On Wed, Mar 03, 2021 at 02:35:33AM +0100, Frederic Weisbecker wrote: > On Tue, Mar 02, 2021 at 10:17:29AM -0800, Paul E. McKenney wrote: > > On Tue, Mar 02, 2021 at 01:34:44PM +0100, Frederic Weisbecker wrote: > > > > OK, how about if I queue a temporary commit (shown below) that just > > calls

Re: [PATCH 01/13] rcu/nocb: Fix potential missed nocb_timer rearm

2021-03-03 Thread Frederic Weisbecker
On Tue, Mar 02, 2021 at 10:17:29AM -0800, Paul E. McKenney wrote: > On Tue, Mar 02, 2021 at 01:34:44PM +0100, Frederic Weisbecker wrote: > > OK, how about if I queue a temporary commit (shown below) that just > calls out the first scenario so that I can start testing, and you get > me more detail

Re: [PATCH 01/13] rcu/nocb: Fix potential missed nocb_timer rearm

2021-03-02 Thread Paul E. McKenney
On Tue, Mar 02, 2021 at 01:34:44PM +0100, Frederic Weisbecker wrote: > On Mon, Mar 01, 2021 at 05:48:29PM -0800, Paul E. McKenney wrote: > > On Wed, Feb 24, 2021 at 11:06:06PM +0100, Frederic Weisbecker wrote: > > > On Wed, Feb 24, 2021 at 10:37:09AM -0800, Paul E. McKenney wrote: > > > > On Tue,

Re: [PATCH 01/13] rcu/nocb: Fix potential missed nocb_timer rearm

2021-03-02 Thread Frederic Weisbecker
On Mon, Mar 01, 2021 at 05:48:29PM -0800, Paul E. McKenney wrote: > On Wed, Feb 24, 2021 at 11:06:06PM +0100, Frederic Weisbecker wrote: > > On Wed, Feb 24, 2021 at 10:37:09AM -0800, Paul E. McKenney wrote: > > > On Tue, Feb 23, 2021 at 01:09:59AM +0100, Frederic Weisbecker wrote: > > > > Two

Re: [PATCH 01/13] rcu/nocb: Fix potential missed nocb_timer rearm

2021-03-01 Thread Paul E. McKenney
On Wed, Feb 24, 2021 at 11:06:06PM +0100, Frederic Weisbecker wrote: > On Wed, Feb 24, 2021 at 10:37:09AM -0800, Paul E. McKenney wrote: > > On Tue, Feb 23, 2021 at 01:09:59AM +0100, Frederic Weisbecker wrote: > > > Two situations can cause a missed nocb timer rearm: > > > > > > 1) rdp(CPU A)

Re: [PATCH 01/13] rcu/nocb: Fix potential missed nocb_timer rearm

2021-02-24 Thread Paul E. McKenney
On Thu, Feb 25, 2021 at 01:48:13AM +0100, Frederic Weisbecker wrote: > On Wed, Feb 24, 2021 at 04:14:25PM -0800, Paul E. McKenney wrote: > > On Wed, Feb 24, 2021 at 11:06:06PM +0100, Frederic Weisbecker wrote: > > > I managed to recollect some pieces of my brain. So keep the above but > > > let's

Re: [PATCH 01/13] rcu/nocb: Fix potential missed nocb_timer rearm

2021-02-24 Thread Frederic Weisbecker
On Wed, Feb 24, 2021 at 04:14:25PM -0800, Paul E. McKenney wrote: > On Wed, Feb 24, 2021 at 11:06:06PM +0100, Frederic Weisbecker wrote: > > I managed to recollect some pieces of my brain. So keep the above but > > let's change the point 10: > > > > 10. CPU 0 enqueues its second callback,

Re: [PATCH 01/13] rcu/nocb: Fix potential missed nocb_timer rearm

2021-02-24 Thread Paul E. McKenney
On Wed, Feb 24, 2021 at 11:06:06PM +0100, Frederic Weisbecker wrote: > On Wed, Feb 24, 2021 at 10:37:09AM -0800, Paul E. McKenney wrote: > > On Tue, Feb 23, 2021 at 01:09:59AM +0100, Frederic Weisbecker wrote: > > > Two situations can cause a missed nocb timer rearm: > > > > > > 1) rdp(CPU A)

Re: [PATCH 01/13] rcu/nocb: Fix potential missed nocb_timer rearm

2021-02-24 Thread Frederic Weisbecker
On Wed, Feb 24, 2021 at 10:37:09AM -0800, Paul E. McKenney wrote: > On Tue, Feb 23, 2021 at 01:09:59AM +0100, Frederic Weisbecker wrote: > > Two situations can cause a missed nocb timer rearm: > > > > 1) rdp(CPU A) queues its nocb timer. The grace period elapses before > >the timer get a

Re: [PATCH 01/13] rcu/nocb: Fix potential missed nocb_timer rearm

2021-02-24 Thread Paul E. McKenney
On Tue, Feb 23, 2021 at 01:09:59AM +0100, Frederic Weisbecker wrote: > Two situations can cause a missed nocb timer rearm: > > 1) rdp(CPU A) queues its nocb timer. The grace period elapses before >the timer get a chance to fire. The nocb_gp kthread is awaken by >rdp(CPU B). The nocb_cb

[PATCH 01/13] rcu/nocb: Fix potential missed nocb_timer rearm

2021-02-22 Thread Frederic Weisbecker
Two situations can cause a missed nocb timer rearm: 1) rdp(CPU A) queues its nocb timer. The grace period elapses before the timer get a chance to fire. The nocb_gp kthread is awaken by rdp(CPU B). The nocb_cb kthread for rdp(CPU A) is awaken and process the callbacks, again before the