Re: [PATCH v2 2/5] sched, numa: Document usages of mm->numa_scan_seq

2015-05-01 Thread Jason Low
On Fri, 2015-05-01 at 08:21 -0700, Paul E. McKenney wrote: > On Thu, Apr 30, 2015 at 02:13:07PM -0700, Jason Low wrote: > > On Thu, 2015-04-30 at 14:42 -0400, Waiman Long wrote: > > > > > I do have a question of what kind of tearing you are talking about. Do > > > you mean the tearing due to mm b

Re: [PATCH v2 2/5] sched, numa: Document usages of mm->numa_scan_seq

2015-05-01 Thread Paul E. McKenney
On Thu, Apr 30, 2015 at 02:13:07PM -0700, Jason Low wrote: > On Thu, 2015-04-30 at 14:42 -0400, Waiman Long wrote: > > > I do have a question of what kind of tearing you are talking about. Do > > you mean the tearing due to mm being changed in the middle of the > > access? The reason why I don't

Re: [PATCH v2 2/5] sched, numa: Document usages of mm->numa_scan_seq

2015-04-30 Thread Jason Low
On Thu, 2015-04-30 at 11:54 -0700, Davidlohr Bueso wrote: > I also wonder why this patch is included in a set called > "sched, timer: Improve scalability of itimers" ;) Good point :) The reason these first 2 patches were included in this patchset is because patch 3 depended on patch 1 (particul

Re: [PATCH v2 2/5] sched, numa: Document usages of mm->numa_scan_seq

2015-04-30 Thread Jason Low
On Thu, 2015-04-30 at 14:42 -0400, Waiman Long wrote: > I do have a question of what kind of tearing you are talking about. Do > you mean the tearing due to mm being changed in the middle of the > access? The reason why I don't like this kind of construct is that I am > not sure if > the addres

Re: [PATCH v2 2/5] sched, numa: Document usages of mm->numa_scan_seq

2015-04-30 Thread Waiman Long
On 04/30/2015 02:54 PM, Davidlohr Bueso wrote: On Thu, 2015-04-30 at 14:42 -0400, Waiman Long wrote: On 04/29/2015 02:45 PM, Jason Low wrote: On Wed, 2015-04-29 at 14:14 -0400, Waiman Long wrote: On 04/28/2015 04:00 PM, Jason Low wrote: The p->mm->numa_scan_seq is accessed using READ_ONCE/WRI

Re: [PATCH v2 2/5] sched, numa: Document usages of mm->numa_scan_seq

2015-04-30 Thread Davidlohr Bueso
On Thu, 2015-04-30 at 14:42 -0400, Waiman Long wrote: > On 04/29/2015 02:45 PM, Jason Low wrote: > > On Wed, 2015-04-29 at 14:14 -0400, Waiman Long wrote: > >> On 04/28/2015 04:00 PM, Jason Low wrote: > >>> The p->mm->numa_scan_seq is accessed using READ_ONCE/WRITE_ONCE > >>> and modified without e

Re: [PATCH v2 2/5] sched, numa: Document usages of mm->numa_scan_seq

2015-04-30 Thread Waiman Long
On 04/29/2015 02:45 PM, Jason Low wrote: On Wed, 2015-04-29 at 14:14 -0400, Waiman Long wrote: On 04/28/2015 04:00 PM, Jason Low wrote: The p->mm->numa_scan_seq is accessed using READ_ONCE/WRITE_ONCE and modified without exclusive access. It is not clear why it is accessed this way. This patch

Re: [PATCH v2 2/5] sched, numa: Document usages of mm->numa_scan_seq

2015-04-29 Thread Jason Low
On Wed, 2015-04-29 at 14:14 -0400, Waiman Long wrote: > On 04/28/2015 04:00 PM, Jason Low wrote: > > The p->mm->numa_scan_seq is accessed using READ_ONCE/WRITE_ONCE > > and modified without exclusive access. It is not clear why it is > > accessed this way. This patch provides some documentation on

Re: [PATCH v2 2/5] sched, numa: Document usages of mm->numa_scan_seq

2015-04-29 Thread Waiman Long
On 04/28/2015 04:00 PM, Jason Low wrote: The p->mm->numa_scan_seq is accessed using READ_ONCE/WRITE_ONCE and modified without exclusive access. It is not clear why it is accessed this way. This patch provides some documentation on that. Signed-off-by: Jason Low --- kernel/sched/fair.c | 12 +

Re: [PATCH v2 2/5] sched, numa: Document usages of mm->numa_scan_seq

2015-04-29 Thread Rik van Riel
On 04/28/2015 04:00 PM, Jason Low wrote: The p->mm->numa_scan_seq is accessed using READ_ONCE/WRITE_ONCE and modified without exclusive access. It is not clear why it is accessed this way. This patch provides some documentation on that. Signed-off-by: Jason Low Acked-by: Rik van Riel -- To