On 01/05/2017 01:50 PM, Steven Rostedt wrote:
> On Thu, 5 Jan 2017 12:07:21 -0500
> Waiman Long wrote:
>
>
>> I do make the assumption that spinlock critical sections are behaving
>> well enough. Apparently, that is not a valid assumption. I sent these
>> RFC patches out to see if it was an idea w
On Thu, 5 Jan 2017 12:07:21 -0500
Waiman Long wrote:
> I do make the assumption that spinlock critical sections are behaving
> well enough. Apparently, that is not a valid assumption. I sent these
> RFC patches out to see if it was an idea worth pursuing. If not, I can
> drop these patches. Anyw
On Wed, 4 Jan 2017 15:02:23 -0500
Waiman Long wrote:
> On 01/04/2017 10:55 AM, Steven Rostedt wrote:
> > On Wed, 4 Jan 2017 10:25:14 -0500
> > Waiman Long wrote:
> >
> >
> >> I know that in -RT kernel, all the non-raw spinlocks are replaced by
> >> rtmutex which is a sleeping lock. This can
On 01/05/2017 05:08 PM, Peter Zijlstra wrote:
> RT very fundamentally relies on the spinlock->rtmutex conversion to
> allow preempting things when a higher priority task comes along. A
> spinlock, of any kind, requires having preemption disabled while holding
> the lock. If the critical section is
On 01/05/2017 11:08 AM, Peter Zijlstra wrote:
> On Thu, Jan 05, 2017 at 10:55:55AM -0500, Waiman Long wrote:
>> What I am saying that we don't need to change spinlock to rtmutex in a
>> -RT kernel. Instead, we can use rtqspinlock for this purpose. All the
>> sleeping locks will still be converted t
On Thu, Jan 05, 2017 at 10:55:55AM -0500, Waiman Long wrote:
> What I am saying that we don't need to change spinlock to rtmutex in a
> -RT kernel. Instead, we can use rtqspinlock for this purpose. All the
> sleeping locks will still be converted to rtmutex.
No-no-no..
> Conversion of rtmutex doe
On 01/05/2017 04:44 AM, Peter Zijlstra wrote:
> On Wed, Jan 04, 2017 at 10:25:14AM -0500, Waiman Long wrote:
>> On 01/04/2017 07:49 AM, Peter Zijlstra wrote:
>>> On Tue, Jan 03, 2017 at 01:00:23PM -0500, Waiman Long wrote:
This patchset introduces a new variant of queued spinlocks - the
r
On Wed, Jan 04, 2017 at 10:25:14AM -0500, Waiman Long wrote:
> On 01/04/2017 07:49 AM, Peter Zijlstra wrote:
> > On Tue, Jan 03, 2017 at 01:00:23PM -0500, Waiman Long wrote:
> >> This patchset introduces a new variant of queued spinlocks - the
> >> realtime queued spinlocks. The purpose of this new
On 01/04/2017 04:25 PM, Waiman Long wrote:
>> OK, so a single numerical field isn't sufficient to describe priority
>> anymore, since we added DEADLINE support things have gotten a lot more
>> complex.
> From what I read from the code, DL tasks all have the same priority that
> is higher than any o
On 01/04/2017 10:55 AM, Steven Rostedt wrote:
> On Wed, 4 Jan 2017 10:25:14 -0500
> Waiman Long wrote:
>
>
>> I know that in -RT kernel, all the non-raw spinlocks are replaced by
>> rtmutex which is a sleeping lock. This can have a real performance
>> impact on systems with more than a few cores
On Wed, 4 Jan 2017 10:25:14 -0500
Waiman Long wrote:
> I know that in -RT kernel, all the non-raw spinlocks are replaced by
> rtmutex which is a sleeping lock. This can have a real performance
> impact on systems with more than a few cores. The rtmutex isn't fair either.
We do fine on 80+ CPUs
On 01/04/2017 07:49 AM, Peter Zijlstra wrote:
> On Tue, Jan 03, 2017 at 01:00:23PM -0500, Waiman Long wrote:
>> This patchset introduces a new variant of queued spinlocks - the
>> realtime queued spinlocks. The purpose of this new variant is to
>> support real spinlock in a realtime environment whe
On Tue, Jan 03, 2017 at 01:00:23PM -0500, Waiman Long wrote:
> This patchset introduces a new variant of queued spinlocks - the
> realtime queued spinlocks. The purpose of this new variant is to
> support real spinlock in a realtime environment where high priority
> RT tasks should be allowed to co
This patchset introduces a new variant of queued spinlocks - the
realtime queued spinlocks. The purpose of this new variant is to
support real spinlock in a realtime environment where high priority
RT tasks should be allowed to complete its work ASAP. This means as
little waiting time for spinlocks
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