Displaying 20 results from an estimated 70 matches for "decode_tail".
2014 May 07
0
[PATCH v10 08/19] qspinlock: Make a new qnode structure to support virtualization
...GNED(struct mcs_spinlock, mcs_nodes[4]);
+static DEFINE_PER_CPU_ALIGNED(struct qnode, qnodes[4]);
/*
* We must be able to distinguish between no-tail and the tail at 0:0,
@@ -79,12 +88,12 @@ static inline u32 encode_tail(int cpu, int idx)
return tail;
}
-static inline struct mcs_spinlock *decode_tail(u32 tail)
+static inline struct qnode *decode_tail(u32 tail)
{
int cpu = (tail >> _Q_TAIL_CPU_OFFSET) - 1;
int idx = (tail & _Q_TAIL_IDX_MASK) >> _Q_TAIL_IDX_OFFSET;
- return per_cpu_ptr(&mcs_nodes[idx], cpu);
+ return per_cpu_ptr(&qnodes[idx], cpu);
}
#define _Q...
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
> + u8 locked;
> + str...
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
> + u8 locked;
> + str...
2014 Apr 17
0
[PATCH v9 04/19] qspinlock: Extract out the exchange of tail code word
...lt; _Q_LOCKED_OFFSET)
#define _Q_PENDING_VAL (1U << _Q_PENDING_OFFSET)
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index d35362a..fcf06cb 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -86,6 +86,34 @@ static inline struct mcs_spinlock *decode_tail(u32 tail)
#define _Q_LOCKED_PENDING_MASK (_Q_LOCKED_MASK | _Q_PENDING_MASK)
/**
+ * xchg_tail - Put in the new queue tail code word & retrieve previous one
+ * @lock : Pointer to queue spinlock structure
+ * @tail : The new queue tail code word
+ * @pval : Pointer to current value of the qu...
2014 Apr 17
0
[PATCH v9 03/19] qspinlock: Add pending bit
...(1U << _Q_PENDING_OFFSET)
#endif /* __ASM_GENERIC_QSPINLOCK_TYPES_H */
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index b97a1ad..d35362a 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -83,23 +83,93 @@ static inline struct mcs_spinlock *decode_tail(u32 tail)
return per_cpu_ptr(&mcs_nodes[idx], cpu);
}
+#define _Q_LOCKED_PENDING_MASK (_Q_LOCKED_MASK | _Q_PENDING_MASK)
+
+/**
+ * trylock_pending - try to acquire queue spinlock using the pending bit
+ * @lock : Pointer to queue spinlock structure
+ * @pval : Pointer to value of the queu...
2014 May 07
0
[PATCH v10 03/19] qspinlock: Add pending bit
...(1U << _Q_PENDING_OFFSET)
#endif /* __ASM_GENERIC_QSPINLOCK_TYPES_H */
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index b97a1ad..6467bfc 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -83,23 +83,97 @@ static inline struct mcs_spinlock *decode_tail(u32 tail)
return per_cpu_ptr(&mcs_nodes[idx], cpu);
}
+#define _Q_LOCKED_PENDING_MASK (_Q_LOCKED_MASK | _Q_PENDING_MASK)
+
+/**
+ * trylock_pending - try to acquire queue spinlock using the pending bit
+ * @lock : Pointer to queue spinlock structure
+ * @pval : Pointer to value of the queu...
2014 Jun 16
4
[PATCH 10/11] qspinlock: Paravirt support
..._spinlock *node)
> +{
> + struct pv_node *pn = (struct pv_node *)node;
> +
> + BUILD_BUG_ON(sizeof(struct pv_node)> 5*sizeof(struct mcs_spinlock));
> +
> + pn->cpu = smp_processor_id();
> + pn->head = INVALID_HEAD;
> +}
> +
> +static inline struct pv_node *pv_decode_tail(u32 tail)
> +{
> + return (struct pv_node *)decode_tail(tail);
> +}
> +
> +void __pv_link_and_wait_node(u32 old, struct mcs_spinlock *node)
> +{
> + struct pv_node *ppn, *pn = (struct pv_node *)node;
> + unsigned int count;
> +
> + if (!(old& _Q_TAIL_MASK)) {
>...
2014 Jun 16
4
[PATCH 10/11] qspinlock: Paravirt support
..._spinlock *node)
> +{
> + struct pv_node *pn = (struct pv_node *)node;
> +
> + BUILD_BUG_ON(sizeof(struct pv_node)> 5*sizeof(struct mcs_spinlock));
> +
> + pn->cpu = smp_processor_id();
> + pn->head = INVALID_HEAD;
> +}
> +
> +static inline struct pv_node *pv_decode_tail(u32 tail)
> +{
> + return (struct pv_node *)decode_tail(tail);
> +}
> +
> +void __pv_link_and_wait_node(u32 old, struct mcs_spinlock *node)
> +{
> + struct pv_node *ppn, *pn = (struct pv_node *)node;
> + unsigned int count;
> +
> + if (!(old& _Q_TAIL_MASK)) {
>...
2014 Jun 23
1
[PATCH 01/11] qspinlock: A simple generic 4-byte queue spinlock
...g.
> > > + */
> > > + if (new == _Q_LOCKED_VAL)
> > > + goto release;
> > > +
> > > + /*
> > > + * if there was a previous node; link it and wait.
> > > + */
> > > + if (old & ~_Q_LOCKED_MASK) {
> > > + prev = decode_tail(old);
> > > + ACCESS_ONCE(prev->next) = node;
> > > +
> > > + arch_mcs_spin_lock_contended(&node->locked);
>
> Could you add a comment here:
>
> /* We are spinning forever until the previous node updates locked - which
> it does once the it ha...
2014 Jun 23
1
[PATCH 01/11] qspinlock: A simple generic 4-byte queue spinlock
...g.
> > > + */
> > > + if (new == _Q_LOCKED_VAL)
> > > + goto release;
> > > +
> > > + /*
> > > + * if there was a previous node; link it and wait.
> > > + */
> > > + if (old & ~_Q_LOCKED_MASK) {
> > > + prev = decode_tail(old);
> > > + ACCESS_ONCE(prev->next) = node;
> > > +
> > > + arch_mcs_spin_lock_contended(&node->locked);
>
> Could you add a comment here:
>
> /* We are spinning forever until the previous node updates locked - which
> it does once the it ha...
2014 Jun 16
4
[PATCH 01/11] qspinlock: A simple generic 4-byte queue spinlock
...> + tail |= idx << _Q_TAIL_IDX_OFFSET; /* assume < 4 */
Should there an
ASSSERT (idx < 4)
just in case we screw up somehow (I can't figure out how, but
that is partially why ASSERTS are added).
> +
> + return tail;
> +}
> +
> +static inline struct mcs_spinlock *decode_tail(u32 tail)
> +{
> + int cpu = (tail >> _Q_TAIL_CPU_OFFSET) - 1;
> + int idx = (tail & _Q_TAIL_IDX_MASK) >> _Q_TAIL_IDX_OFFSET;
> +
> + return per_cpu_ptr(&mcs_nodes[idx], cpu);
> +}
> +
> +/**
> + * queue_spin_lock_slowpath - acquire the queue spinlock...
2014 Jun 16
4
[PATCH 01/11] qspinlock: A simple generic 4-byte queue spinlock
...> + tail |= idx << _Q_TAIL_IDX_OFFSET; /* assume < 4 */
Should there an
ASSSERT (idx < 4)
just in case we screw up somehow (I can't figure out how, but
that is partially why ASSERTS are added).
> +
> + return tail;
> +}
> +
> +static inline struct mcs_spinlock *decode_tail(u32 tail)
> +{
> + int cpu = (tail >> _Q_TAIL_CPU_OFFSET) - 1;
> + int idx = (tail & _Q_TAIL_IDX_MASK) >> _Q_TAIL_IDX_OFFSET;
> +
> + return per_cpu_ptr(&mcs_nodes[idx], cpu);
> +}
> +
> +/**
> + * queue_spin_lock_slowpath - acquire the queue spinlock...
2015 Mar 19
0
[PATCH 8/9] qspinlock: Generic paravirt support
...-static __always_inline void __pv_wait_head(struct qspinlock *lock) { }
+static __always_inline void __pv_wait_head(struct qspinlock *lock, struct mcs_spinlock *node) { }
#define pv_enabled() false
@@ -399,7 +399,7 @@ void queue_spin_lock_slowpath(struct qsp
prev = decode_tail(old);
WRITE_ONCE(prev->next, node);
- pv_wait_node(node);
+ pv_wait_node(old, node);
arch_mcs_spin_lock_contended(&node->locked);
}
@@ -414,7 +414,7 @@ void queue_spin_lock_slowpath(struct qsp
* sequentiality...
2015 Mar 19
0
[PATCH 8/9] qspinlock: Generic paravirt support
...-static __always_inline void __pv_wait_head(struct qspinlock *lock) { }
+static __always_inline void __pv_wait_head(struct qspinlock *lock, struct mcs_spinlock *node) { }
#define pv_enabled() false
@@ -399,7 +399,7 @@ void queue_spin_lock_slowpath(struct qsp
prev = decode_tail(old);
WRITE_ONCE(prev->next, node);
- pv_wait_node(node);
+ pv_wait_node(old, node);
arch_mcs_spin_lock_contended(&node->locked);
}
@@ -414,7 +414,7 @@ void queue_spin_lock_slowpath(struct qsp
* sequentiality...
2014 Jun 15
28
[PATCH 00/11] qspinlock with paravirt support
Since Waiman seems incapable of doing simple things; here's my take on the
paravirt crap.
The first few patches are taken from Waiman's latest series, but the virt
support is completely new. Its primary aim is to not mess up the native code.
I've not stress tested it, but the virt and paravirt (kvm) cases boot on simple
smp guests. I've not done Xen, but the patch should be
2014 Jun 15
28
[PATCH 00/11] qspinlock with paravirt support
Since Waiman seems incapable of doing simple things; here's my take on the
paravirt crap.
The first few patches are taken from Waiman's latest series, but the virt
support is completely new. Its primary aim is to not mess up the native code.
I've not stress tested it, but the virt and paravirt (kvm) cases boot on simple
smp guests. I've not done Xen, but the patch should be
2014 May 30
19
[PATCH v11 00/16] qspinlock: a 4-byte queue spinlock with PV support
v10->v11:
- Use a simple test-and-set unfair lock to simplify the code,
but performance may suffer a bit for large guest with many CPUs.
- Take out Raghavendra KT's test results as the unfair lock changes
may render some of his results invalid.
- Add PV support without increasing the size of the core queue node
structure.
- Other minor changes to address some of the
2014 May 30
19
[PATCH v11 00/16] qspinlock: a 4-byte queue spinlock with PV support
v10->v11:
- Use a simple test-and-set unfair lock to simplify the code,
but performance may suffer a bit for large guest with many CPUs.
- Take out Raghavendra KT's test results as the unfair lock changes
may render some of his results invalid.
- Add PV support without increasing the size of the core queue node
structure.
- Other minor changes to address some of the
2014 Jun 15
0
[PATCH 10/11] qspinlock: Paravirt support
...HEAD nr_cpu_ids
+
+void __pv_init_node(struct mcs_spinlock *node)
+{
+ struct pv_node *pn = (struct pv_node *)node;
+
+ BUILD_BUG_ON(sizeof(struct pv_node) > 5*sizeof(struct mcs_spinlock));
+
+ pn->cpu = smp_processor_id();
+ pn->head = INVALID_HEAD;
+}
+
+static inline struct pv_node *pv_decode_tail(u32 tail)
+{
+ return (struct pv_node *)decode_tail(tail);
+}
+
+void __pv_link_and_wait_node(u32 old, struct mcs_spinlock *node)
+{
+ struct pv_node *ppn, *pn = (struct pv_node *)node;
+ unsigned int count;
+
+ if (!(old & _Q_TAIL_MASK)) {
+ pn->head = NO_HEAD;
+ return;
+ }
+
+ ppn = pv_...
2014 Jun 17
3
[PATCH 04/11] qspinlock: Extract out the exchange of tail code word
...-> n,*,*
> */
> - if (new == _Q_LOCKED_VAL)
> - goto release;
> + old = xchg_tail(lock, tail);
>
> /*
> * if there was a previous node; link it and wait.
> */
> - if (old & ~_Q_LOCKED_PENDING_MASK) {
> + if (old & _Q_TAIL_MASK) {
> prev = decode_tail(old);
> ACCESS_ONCE(prev->next) = node;
>
>
>