On Wed, Jun 15, 2016 at 03:01:19PM -0400, Waiman Long wrote:
> On 06/15/2016 04:04 AM, Boqun Feng wrote:
> > Hi Waiman,
> >
> > On Tue, Jun 14, 2016 at 06:48:04PM -0400, Waiman Long wrote:
> > > The osq_lock() and osq_unlock() function may not provide the necessary
> > > acquire and release
On 06/15/2016 01:45 PM, Peter Zijlstra wrote:
On Tue, Jun 14, 2016 at 06:48:08PM -0400, Waiman Long wrote:
+++ b/arch/alpha/include/asm/rwsem.h
@@ -17,9 +17,9 @@
#define RWSEM_UNLOCKED_VALUE 0xL
#define RWSEM_ACTIVE_BIAS 0x0001L
#define
On 06/15/2016 01:43 PM, Peter Zijlstra wrote:
On Tue, Jun 14, 2016 at 06:48:08PM -0400, Waiman Long wrote:
even the reduced maximum of about 16k (32-bit) or 1G (64-bit) should
be more than enough for the foreseeable future.
So what happens if I manage to create 16k+ threads on my 32bit kernel
On 06/15/2016 01:40 PM, Peter Zijlstra wrote:
On Tue, Jun 14, 2016 at 06:48:07PM -0400, Waiman Long wrote:
Move the rwsem_down_read_failed() function down to below the optimistic
spinning section before enabling optimistic spinning for the readers.
newline
There is no change in code.
On 06/15/2016 01:22 PM, Peter Zijlstra wrote:
On Tue, Jun 14, 2016 at 06:48:05PM -0400, Waiman Long wrote:
Currently, when down_read() fails, the active read locking isn't undone
until the rwsem_down_read_failed() function grabs the wait_lock. If the
wait_lock is contended, it may takes a while
On 06/15/2016 01:12 PM, Peter Zijlstra wrote:
On Wed, Jun 15, 2016 at 09:56:59AM -0700, Davidlohr Bueso wrote:
On Tue, 14 Jun 2016, Waiman Long wrote:
+++ b/kernel/locking/osq_lock.c
@@ -115,7 +115,7 @@ bool osq_lock(struct optimistic_spin_queue *lock)
* cmpxchg in an attempt to undo
On Wed, 15 Jun 2016, Peter Zijlstra wrote:
On Wed, Jun 15, 2016 at 11:27:24AM -0700, Davidlohr Bueso wrote:
On Wed, 15 Jun 2016, Peter Zijlstra wrote:
>In any case, its fairly simple to cure, just add
>smp_acquire__after_ctrl_dep() at the end. If we bail because
>need_resched() we don't need
On Tue, Jun 14, 2016 at 06:48:07PM -0400, Waiman Long wrote:
> Move the rwsem_down_read_failed() function down to below the optimistic
> spinning section before enabling optimistic spinning for the readers.
newline
> There is no change in code.
Changelog fails to explain the why part.
--
To
On Tue, Jun 14, 2016 at 06:48:06PM -0400, Waiman Long wrote:
> static bool rwsem_optimistic_spin(struct rw_semaphore *sem)
> {
> - bool taken = false;
> + bool taken = false, can_spin;
I would place the variables without assignment first.
> + int loopcnt;
>
>
On Tue, Jun 14, 2016 at 06:48:05PM -0400, Waiman Long wrote:
> Currently, when down_read() fails, the active read locking isn't undone
> until the rwsem_down_read_failed() function grabs the wait_lock. If the
> wait_lock is contended, it may takes a while to get the lock. During
> that period,
On Wed, Jun 15, 2016 at 04:04:46PM +0800, Boqun Feng wrote:
> On Tue, Jun 14, 2016 at 06:48:04PM -0400, Waiman Long wrote:
> > @@ -198,7 +198,7 @@ void osq_unlock(struct optimistic_spin_queue *lock)
> > * Second most likely case.
> > */
> > node = this_cpu_ptr(_node);
> > - next =
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