On 08/21/2017 03:42 PM, Peter Zijlstra wrote:
> On Mon, Aug 21, 2017 at 09:25:50PM +0200, Peter Zijlstra wrote:
>> On Mon, Aug 21, 2017 at 07:00:02PM +0100, Will Deacon wrote:
No, I meant _from_ the LL load, not _to_ a later load.
>>> Sorry, I'm still not following enough to give you a definit
On Mon, Aug 21, 2017 at 09:25:50PM +0200, Peter Zijlstra wrote:
> On Mon, Aug 21, 2017 at 07:00:02PM +0100, Will Deacon wrote:
> > > No, I meant _from_ the LL load, not _to_ a later load.
> >
> > Sorry, I'm still not following enough to give you a definitive answer on
> > that. Could you give an e
On Mon, Aug 21, 2017 at 09:25:50PM +0200, Peter Zijlstra wrote:
> On Mon, Aug 21, 2017 at 07:00:02PM +0100, Will Deacon wrote:
> > > No, I meant _from_ the LL load, not _to_ a later load.
> >
> > Sorry, I'm still not following enough to give you a definitive answer on
> > that. Could you give an e
On Mon, Aug 21, 2017 at 07:00:02PM +0100, Will Deacon wrote:
> > No, I meant _from_ the LL load, not _to_ a later load.
>
> Sorry, I'm still not following enough to give you a definitive answer on
> that. Could you give an example, please? These sequences usually run in
> a loop, so the conditiona
On Mon, Aug 21, 2017 at 12:55:08PM +0200, Peter Zijlstra wrote:
> On Tue, Aug 15, 2017 at 07:40:35PM +0100, Will Deacon wrote:
> > On Mon, Aug 14, 2017 at 08:47:11PM +0200, Peter Zijlstra wrote:
> > > On Mon, Aug 14, 2017 at 01:01:22PM +0100, Will Deacon wrote:
> > > > Yeah, that's right, you can't
On Tue, Aug 15, 2017 at 07:40:35PM +0100, Will Deacon wrote:
> On Mon, Aug 14, 2017 at 08:47:11PM +0200, Peter Zijlstra wrote:
> > On Mon, Aug 14, 2017 at 01:01:22PM +0100, Will Deacon wrote:
> > > Yeah, that's right, you can't use the STXR status flag to create control
> > > dependencies.
> >
> >
On Mon, Aug 14, 2017 at 08:47:11PM +0200, Peter Zijlstra wrote:
> On Mon, Aug 14, 2017 at 01:01:22PM +0100, Will Deacon wrote:
> > Yeah, that's right, you can't use the STXR status flag to create control
> > dependencies.
>
> Just for my elucidation; you can't use it to create a control dependency
On Mon, Aug 14, 2017 at 01:01:22PM +0100, Will Deacon wrote:
> Yeah, that's right, you can't use the STXR status flag to create control
> dependencies.
Just for my elucidation; you can't use it to create a control dependency
on the store, but you can use it to create a control dependency on the
co
On Mon, Aug 14, 2017 at 11:01:10AM -0400, Waiman Long wrote:
> On 08/14/2017 08:01 AM, Will Deacon wrote:
> > On Fri, Aug 11, 2017 at 11:06:01AM +0200, Peter Zijlstra wrote:
> >> On Thu, Aug 10, 2017 at 02:18:30PM -0400, Waiman Long wrote:
> >>> On 08/10/2017 12:22 PM, Waiman Long wrote:
> On
On 08/14/2017 08:01 AM, Will Deacon wrote:
> On Fri, Aug 11, 2017 at 11:06:01AM +0200, Peter Zijlstra wrote:
>> On Thu, Aug 10, 2017 at 02:18:30PM -0400, Waiman Long wrote:
>>> On 08/10/2017 12:22 PM, Waiman Long wrote:
On 08/10/2017 12:15 PM, Peter Zijlstra wrote:
> Might as well do an ex
On Fri, Aug 11, 2017 at 11:06:01AM +0200, Peter Zijlstra wrote:
> On Thu, Aug 10, 2017 at 02:18:30PM -0400, Waiman Long wrote:
> > On 08/10/2017 12:22 PM, Waiman Long wrote:
> > > On 08/10/2017 12:15 PM, Peter Zijlstra wrote:
>
> > >> Might as well do an explicit:
> > >>
> > >> smp_mb__before_ato
On Thu, Aug 10, 2017 at 02:18:30PM -0400, Waiman Long wrote:
> On 08/10/2017 12:22 PM, Waiman Long wrote:
> > On 08/10/2017 12:15 PM, Peter Zijlstra wrote:
> >> Might as well do an explicit:
> >>
> >>smp_mb__before_atomic()
> >>cmpxchg_relaxed()
> >>smp_mb__after_atomic()
> >>
> >> I s
On Thu, Aug 10, 2017 at 11:13:17AM +0200, Peter Zijlstra wrote:
> On Thu, Aug 10, 2017 at 04:12:13PM +0800, Boqun Feng wrote:
>
> > > Or is the reason this doesn't work on PPC that its RCpc?
>
> So that :-)
>
> > Here is an example why PPC needs a sync() before the cmpxchg():
> >
> > https:
On 08/10/2017 12:22 PM, Waiman Long wrote:
> On 08/10/2017 12:15 PM, Peter Zijlstra wrote:
>> On Thu, Aug 10, 2017 at 09:58:57AM -0400, Waiman Long wrote:
>>> On 08/10/2017 09:27 AM, Waiman Long wrote:
On 08/10/2017 07:50 AM, Peter Zijlstra wrote:
> On Wed, May 24, 2017 at 09:38:28AM -0400
On 08/10/2017 12:15 PM, Peter Zijlstra wrote:
> On Thu, Aug 10, 2017 at 09:58:57AM -0400, Waiman Long wrote:
>> On 08/10/2017 09:27 AM, Waiman Long wrote:
>>> On 08/10/2017 07:50 AM, Peter Zijlstra wrote:
On Wed, May 24, 2017 at 09:38:28AM -0400, Waiman Long wrote:
> # of thread w/o
On Thu, Aug 10, 2017 at 09:58:57AM -0400, Waiman Long wrote:
> On 08/10/2017 09:27 AM, Waiman Long wrote:
> > On 08/10/2017 07:50 AM, Peter Zijlstra wrote:
> >> On Wed, May 24, 2017 at 09:38:28AM -0400, Waiman Long wrote:
> >>> # of thread w/o patchwith patch % Change
> >>> ---
On 08/10/2017 09:27 AM, Waiman Long wrote:
> On 08/10/2017 07:50 AM, Peter Zijlstra wrote:
>> On Wed, May 24, 2017 at 09:38:28AM -0400, Waiman Long wrote:
>>> # of thread w/o patchwith patch % Change
>>> --- ---
>>>4 405
On 08/10/2017 07:50 AM, Peter Zijlstra wrote:
> On Wed, May 24, 2017 at 09:38:28AM -0400, Waiman Long wrote:
>> # of thread w/o patchwith patch % Change
>> --- ---
>>4 4053.3 Mop/s 4223.7 Mop/s +4.2%
>>8
On Wed, May 24, 2017 at 09:38:28AM -0400, Waiman Long wrote:
>
> # of thread w/o patchwith patch % Change
> --- ---
>4 4053.3 Mop/s 4223.7 Mop/s +4.2%
>8 3310.4 Mop/s 3406.0 Mop/s +2.9%
>
On Thu, Aug 10, 2017 at 04:12:13PM +0800, Boqun Feng wrote:
> > Or is the reason this doesn't work on PPC that its RCpc?
So that :-)
> Here is an example why PPC needs a sync() before the cmpxchg():
>
> https://marc.info/?l=linux-kernel&m=144485396224519&w=2
>
> and Paul Mckenney's detai
On Wed, Aug 09, 2017 at 05:15:33PM +0200, Peter Zijlstra wrote:
> On Wed, Aug 09, 2017 at 05:06:03PM +0200, Peter Zijlstra wrote:
> > Now, ARM64 for instance plays funny games, it does something along the
> > lines of:
> >
> > cmpxchg(ptr, old, new)
> > {
> > do {
> > r = LL(ptr);
On Wed, Aug 09, 2017 at 05:06:03PM +0200, Peter Zijlstra wrote:
> Now, ARM64 for instance plays funny games, it does something along the
> lines of:
>
> cmpxchg(ptr, old, new)
> {
> do {
> r = LL(ptr);
> if (r != old)
> return r; /* no barrie
On Wed, May 24, 2017 at 09:38:28AM -0400, Waiman Long wrote:
> @@ -361,6 +361,13 @@ static void pv_kick_node(struct qspinlock *lock, struct
> mcs_spinlock *node)
>* observe its next->locked value and advance itself.
>*
>* Matches with smp_store_mb() and cmpxchg() in pv_wai
On 05/24/2017 09:38 AM, Waiman Long wrote:
> All the locking related cmpxchg's in the following functions are
> replaced with the _acquire variants:
> - pv_queued_spin_steal_lock()
> - trylock_clear_pending()
>
> This change should help performance on architectures that use LL/SC.
>
> On a 2-core
All the locking related cmpxchg's in the following functions are
replaced with the _acquire variants:
- pv_queued_spin_steal_lock()
- trylock_clear_pending()
This change should help performance on architectures that use LL/SC.
On a 2-core 16-thread Power8 system with pvqspinlock explicitly
enab
在 2017/2/23 22:13, Waiman Long 写道:
All the locking related cmpxchg's in the following functions are
replaced with the _acquire variants:
- pv_queued_spin_steal_lock()
- trylock_clear_pending()
This change should help performance on architectures that use LL/SC.
On a 2-core 16-thread Power8
All the locking related cmpxchg's in the following functions are
replaced with the _acquire variants:
- pv_queued_spin_steal_lock()
- trylock_clear_pending()
This change should help performance on architectures that use LL/SC.
On a 2-core 16-thread Power8 system with pvqspinlock explicitly
enab
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