Displaying 20 results from an estimated 26 matches for "get_qlock".
2014 May 08
1
[PATCH v10 07/19] qspinlock: Use a simple write to grab the lock, if applicable
On Wed, May 07, 2014 at 11:01:35AM -0400, Waiman Long wrote:
> /**
> + * get_qlock - Set the lock bit and own the lock
> + * @lock: Pointer to queue spinlock structure
> + *
> + * This routine should only be called when the caller is the only one
> + * entitled to acquire the lock.
> + */
> +static __always_inline void get_qlock(struct qspinlock *lock)
set_lock...
2014 May 08
1
[PATCH v10 07/19] qspinlock: Use a simple write to grab the lock, if applicable
On Wed, May 07, 2014 at 11:01:35AM -0400, Waiman Long wrote:
> /**
> + * get_qlock - Set the lock bit and own the lock
> + * @lock: Pointer to queue spinlock structure
> + *
> + * This routine should only be called when the caller is the only one
> + * entitled to acquire the lock.
> + */
> +static __always_inline void get_qlock(struct qspinlock *lock)
set_lock...
2014 May 07
0
[PATCH v10 09/19] qspinlock: Prepare for unfair lock support
...king/qspinlock.c
@@ -64,6 +64,7 @@
struct qnode {
struct mcs_spinlock mcs;
};
+#define qhead mcs.locked /* The queue head flag */
/*
* Per-CPU queue node structures; we can never have more than 4 nested
@@ -216,18 +217,20 @@ xchg_tail(struct qspinlock *lock, u32 tail, u32 *pval)
/**
* get_qlock - Set the lock bit and own the lock
- * @lock: Pointer to queue spinlock structure
+ * @lock : Pointer to queue spinlock structure
+ * Return: 1 if lock acquired, 0 otherwise
*
* This routine should only be called when the caller is the only one
* entitled to acquire the lock.
*/
-static __...
2014 May 08
2
[PATCH v10 09/19] qspinlock: Prepare for unfair lock support
...end of
> the queue_spin_lock_slowpath() function may need to detect the fact
> the lock can be stolen. Code are added for the stolen lock detection.
>
> A new qhead macro is also defined as a shorthand for mcs.locked.
NAK, unfair should be a pure test-and-set lock.
> /**
> * get_qlock - Set the lock bit and own the lock
> - * @lock: Pointer to queue spinlock structure
> + * @lock : Pointer to queue spinlock structure
> + * Return: 1 if lock acquired, 0 otherwise
> *
> * This routine should only be called when the caller is the only one
> * entitled to acq...
2014 May 08
2
[PATCH v10 09/19] qspinlock: Prepare for unfair lock support
...end of
> the queue_spin_lock_slowpath() function may need to detect the fact
> the lock can be stolen. Code are added for the stolen lock detection.
>
> A new qhead macro is also defined as a shorthand for mcs.locked.
NAK, unfair should be a pure test-and-set lock.
> /**
> * get_qlock - Set the lock bit and own the lock
> - * @lock: Pointer to queue spinlock structure
> + * @lock : Pointer to queue spinlock structure
> + * Return: 1 if lock acquired, 0 otherwise
> *
> * This routine should only be called when the caller is the only one
> * entitled to acq...
2014 Apr 17
0
[PATCH v9 07/19] qspinlock: Use a simple write to grab the lock, if applicable
...;
+ };
+#endif
};
};
+#if _Q_PENDING_BITS == 8
/**
* clear_pending_set_locked - take ownership and clear the pending bit.
* @lock: Pointer to queue spinlock structure
@@ -204,6 +210,22 @@ xchg_tail(struct qspinlock *lock, u32 tail, u32 *pval)
#endif /* _Q_PENDING_BITS == 8 */
/**
+ * get_qlock - Set the lock bit and own the lock
+ * @lock: Pointer to queue spinlock structure
+ *
+ * This routine should only be called when the caller is the only one
+ * entitled to acquire the lock.
+ */
+static __always_inline void get_qlock(struct qspinlock *lock)
+{
+ struct __qspinlock *l = (void *)lo...
2014 May 07
0
[PATCH v10 07/19] qspinlock: Use a simple write to grab the lock, if applicable
...;
+ };
+#endif
};
};
+#if _Q_PENDING_BITS == 8
/**
* clear_pending_set_locked - take ownership and clear the pending bit.
* @lock: Pointer to queue spinlock structure
@@ -200,6 +206,22 @@ xchg_tail(struct qspinlock *lock, u32 tail, u32 *pval)
#endif /* _Q_PENDING_BITS == 8 */
/**
+ * get_qlock - Set the lock bit and own the lock
+ * @lock: Pointer to queue spinlock structure
+ *
+ * This routine should only be called when the caller is the only one
+ * entitled to acquire the lock.
+ */
+static __always_inline void get_qlock(struct qspinlock *lock)
+{
+ struct __qspinlock *l = (void *)lo...
2014 May 10
0
[PATCH v10 09/19] qspinlock: Prepare for unfair lock support
...imple test-and-set lock does not
scale well. That is the primary reason of ditching the test-and-set lock
and use a more complicated scheme which scales better. Also, it will be
hard to make the unfair test-and-set lock code to coexist nicely with PV
spinlock code.
>> /**
>> * get_qlock - Set the lock bit and own the lock
>> - * @lock: Pointer to queue spinlock structure
>> + * @lock : Pointer to queue spinlock structure
>> + * Return: 1 if lock acquired, 0 otherwise
>> *
>> * This routine should only be called when the caller is the only one
&g...
2014 May 08
1
[PATCH v10 10/19] qspinlock, x86: Allow unfair spinlock in a virtual guest
...ote:
No, we want the unfair thing for VIRT, not PARAVIRT.
> diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
> index 9e7659e..10e87e1 100644
> --- a/kernel/locking/qspinlock.c
> +++ b/kernel/locking/qspinlock.c
> @@ -227,6 +227,14 @@ static __always_inline int get_qlock(struct qspinlock *lock)
> {
> struct __qspinlock *l = (void *)lock;
>
> +#ifdef CONFIG_PARAVIRT_UNFAIR_LOCKS
> + if (static_key_false(¶virt_unfairlocks_enabled))
> + /*
> + * Need to use atomic operation to get the lock when
> + * lock stealing can happen....
2014 May 08
1
[PATCH v10 10/19] qspinlock, x86: Allow unfair spinlock in a virtual guest
...ote:
No, we want the unfair thing for VIRT, not PARAVIRT.
> diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
> index 9e7659e..10e87e1 100644
> --- a/kernel/locking/qspinlock.c
> +++ b/kernel/locking/qspinlock.c
> @@ -227,6 +227,14 @@ static __always_inline int get_qlock(struct qspinlock *lock)
> {
> struct __qspinlock *l = (void *)lock;
>
> +#ifdef CONFIG_PARAVIRT_UNFAIR_LOCKS
> + if (static_key_false(¶virt_unfairlocks_enabled))
> + /*
> + * Need to use atomic operation to get the lock when
> + * lock stealing can happen....
2014 May 07
32
[PATCH v10 00/19] qspinlock: a 4-byte queue spinlock with PV support
v9->v10:
- Make some minor changes to qspinlock.c to accommodate review feedback.
- Change author to PeterZ for 2 of the patches.
- Include Raghavendra KT's test results in patch 18.
v8->v9:
- Integrate PeterZ's version of the queue spinlock patch with some
modification:
http://lkml.kernel.org/r/20140310154236.038181843 at infradead.org
- Break the more complex
2014 May 07
32
[PATCH v10 00/19] qspinlock: a 4-byte queue spinlock with PV support
v9->v10:
- Make some minor changes to qspinlock.c to accommodate review feedback.
- Change author to PeterZ for 2 of the patches.
- Include Raghavendra KT's test results in patch 18.
v8->v9:
- Integrate PeterZ's version of the queue spinlock patch with some
modification:
http://lkml.kernel.org/r/20140310154236.038181843 at infradead.org
- Break the more complex
2014 May 21
0
[RFC 08/07] qspinlock: integrate pending bit into queue
...till here; safe
old = xchg_tail(lock, tail, &val);
/*
@@ -386,41 +458,45 @@ void queue_spin_lock_slowpath(struct qspinlock *lock, u32 val)
}
/*
- * we're at the head of the waitqueue, wait for the owner & pending to
- * go away.
- * Load-acquired is used here because the get_qlock()
- * function below may not be a full memory barrier.
- *
- * *,x,y -> *,0,0
+ * We are now waiting for the pending bit to get cleared.
*/
- while ((val = smp_load_acquire(&lock->val.counter))
- & _Q_LOCKED_PENDING_MASK)
+ // make a get_pending(lock, &val) helper...
2014 Apr 17
33
[PATCH v9 00/19] qspinlock: a 4-byte queue spinlock with PV support
v8->v9:
- Integrate PeterZ's version of the queue spinlock patch with some
modification:
http://lkml.kernel.org/r/20140310154236.038181843 at infradead.org
- Break the more complex patches into smaller ones to ease review effort.
- Fix a racing condition in the PV qspinlock code.
v7->v8:
- Remove one unneeded atomic operation from the slowpath, thus
improving
2014 Apr 17
33
[PATCH v9 00/19] qspinlock: a 4-byte queue spinlock with PV support
v8->v9:
- Integrate PeterZ's version of the queue spinlock patch with some
modification:
http://lkml.kernel.org/r/20140310154236.038181843 at infradead.org
- Break the more complex patches into smaller ones to ease review effort.
- Fix a racing condition in the PV qspinlock code.
v7->v8:
- Remove one unneeded atomic operation from the slowpath, thus
improving
2014 May 08
1
[PATCH v10 07/19] qspinlock: Use a simple write to grab the lock, if applicable
On Wed, May 07, 2014 at 11:01:35AM -0400, Waiman Long wrote:
> @@ -94,23 +94,29 @@ static inline struct mcs_spinlock *decode_tail(u32 tail)
> * can allow better optimization of the lock acquisition for the pending
> * bit holder.
> */
> -#if _Q_PENDING_BITS == 8
> -
> struct __qspinlock {
> union {
> atomic_t val;
> - struct {
> #ifdef __LITTLE_ENDIAN
2014 May 08
1
[PATCH v10 07/19] qspinlock: Use a simple write to grab the lock, if applicable
On Wed, May 07, 2014 at 11:01:35AM -0400, Waiman Long wrote:
> @@ -94,23 +94,29 @@ static inline struct mcs_spinlock *decode_tail(u32 tail)
> * can allow better optimization of the lock acquisition for the pending
> * bit holder.
> */
> -#if _Q_PENDING_BITS == 8
> -
> struct __qspinlock {
> union {
> atomic_t val;
> - struct {
> #ifdef __LITTLE_ENDIAN
2014 May 14
2
[PATCH v10 03/19] qspinlock: Add pending bit
2014-05-14 19:00+0200, Peter Zijlstra:
> On Wed, May 14, 2014 at 06:51:24PM +0200, Radim Kr?m?? wrote:
> > Ok.
> > I've seen merit in pvqspinlock even with slightly slower first-waiter,
> > so I would have happily sacrificed those horrible branches.
> > (I prefer elegant to optimized code, but I can see why we want to be
> > strictly better than ticketlock.)
2014 May 14
2
[PATCH v10 03/19] qspinlock: Add pending bit
2014-05-14 19:00+0200, Peter Zijlstra:
> On Wed, May 14, 2014 at 06:51:24PM +0200, Radim Kr?m?? wrote:
> > Ok.
> > I've seen merit in pvqspinlock even with slightly slower first-waiter,
> > so I would have happily sacrificed those horrible branches.
> > (I prefer elegant to optimized code, but I can see why we want to be
> > strictly better than ticketlock.)
2014 Apr 23
0
[PATCH v9 05/19] qspinlock: Optimize for smaller NR_CPUS
...clear_pending_set_locked(struct qspinlock *lock, u32 val)
> {
> struct __qspinlock *l = (void *)lock;
>
> - ACCESS_ONCE(l->locked_pending) = 1;
> + ACCESS_ONCE(l->locked_pending) = _Q_LOCKED_VAL;
> }
>
> /*
> @@ -567,16 +563,16 @@ static __always_inline int get_qlock(struct qspinlock *lock)
> /**
> * trylock_pending - try to acquire queue spinlock using the pending bit
> * @lock : Pointer to queue spinlock structure
> - * @pval : Pointer to value of the queue spinlock 32-bit word
> + * @val : Current value of the queue spinlock 32-bit word...