Re: [PATCH 3/4] locking/osq_lock: From x_osq_lock/unlock to numa-aware lock/unlock.
From: Waiman Long
Date: Sat Sep 14 2024 - 13:13:18 EST
On 9/14/24 04:53, yongli-oc wrote:
According to the contention level, switches from x_osq_lock to
numa-aware osq_lock.
The numa-aware lock is a two level osq_lock.
The Makefile for dynamic numa-aware osq lock.
Signed-off-by: yongli-oc <yongli-oc@xxxxxxxxxxx>
---
kernel/locking/Makefile | 1 +
kernel/locking/numa.h | 98 ++++++++
kernel/locking/numa_osq.h | 32 +++
kernel/locking/x_osq_lock.c | 332 +++++++++++++++++++++++++++
kernel/locking/zx_numa_osq.c | 433 +++++++++++++++++++++++++++++++++++
5 files changed, 896 insertions(+)
create mode 100644 kernel/locking/numa.h
create mode 100644 kernel/locking/numa_osq.h
create mode 100644 kernel/locking/x_osq_lock.c
create mode 100644 kernel/locking/zx_numa_osq.c
diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
index 0db4093d17b8..00c1d5bb6eb9 100644
--- a/kernel/locking/Makefile
+++ b/kernel/locking/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_LOCKDEP) += lockdep_proc.o
endif
obj-$(CONFIG_SMP) += spinlock.o
obj-$(CONFIG_LOCK_SPIN_ON_OWNER) += osq_lock.o
+obj-$(CONFIG_LOCK_SPIN_ON_OWNER_NUMA) += x_osq_lock.o zx_numa_osq.o zx_numa.o
obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
obj-$(CONFIG_QUEUED_SPINLOCKS) += qspinlock.o
obj-$(CONFIG_RT_MUTEXES) += rtmutex_api.o
diff --git a/kernel/locking/numa.h b/kernel/locking/numa.h
new file mode 100644
index 000000000000..01e5aef3257a
--- /dev/null
+++ b/kernel/locking/numa.h
@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_NUMA_LOCK_H
+#define __LINUX_NUMA_LOCK_H
+#include "mcs_spinlock.h"
+
+struct optimistic_spin_node {
+ struct optimistic_spin_node *next, *prev;
+ int numa;
+ int locked; /* 1 if lock acquired */
+ int cpu; /* encoded CPU # + 1 value */
+ u32 serial;
+};
+
+
+struct _numa_buf {
+ void *numa_ptr;
+ struct list_head list;
+ u32 lockaddr;
+ u32 highaddr;
+ u8 idle;
+ u8 type;
+ u16 index;
+};
+
+struct cache_padding {
+ char x[0];
+} ____cacheline_internodealigned_in_smp;
+#define CACHE_PADDING(name) struct cache_padding name
We have struct cacheline_padding and CACHELINE_PADDING() in
include/linux/cache. What is the point of reinventing the same thing here?
+
+struct _numa_lock {
+ atomic_t tail ____cacheline_aligned_in_smp;
+ atomic_t addr;
+ u8 shift;
+ u8 stopping;
+ u16 numa_nodes;
+ u32 accessed;
+ uint64_t totalaccessed;
+ u32 nodeswitched;
+ atomic_t initlock;
+ atomic_t pending;
+ union {
+ struct mcs_spinlock mcs_node;
+ struct optimistic_spin_node osq_node;
+ };
+ CACHE_PADDING(pad);
+};
+
+struct numa_cpu_info {
+ __u8 x86_model;
+ /* CPU family */
+ __u8 x86;
+ /* CPU vendor */
+ __u8 x86_vendor;
+ __u8 x86_reserved;
+ u32 feature1;
+};
+
+#define NUMAEXPAND 1
+
+#define COHORT_START 1
+#define ACQUIRE_NUMALOCK (UINT_MAX-1)
+#define NODE_WAIT UINT_MAX
+#define LOCK_NUMALOCK 1
+#define UNLOCK_NUMALOCK 0
+
+#define NUMALOCKDYNAMIC 0xff
+#define TURNTONUMAREADY 0xa5a5
+#define NUMATURNBACKREADY 0x5a5a
+
+#define NUMA_LOCKED_VAL 0xf5efef
What are these special bit values for?
+#define NUMA_UNLOCKED_VAL 0
+
+#define NUMASTEERMASK 0xf0000000
+#define HIGH32BITMASK 0xffffffff00000000
+#define LOW32MASK 0xffffffff
+
+extern int NUMASHIFT;
+extern int NUMACLUSTERS;
In the kernel, uppercase names are used for macros. Variables should use
all lowercase names to avoid confusion.
+extern int zx_numa_lock_total;
+extern struct _numa_buf *zx_numa_entry;
+extern atomic_t numa_count;
+extern int enable_zx_numa_osq_lock;
+extern u32 zx_numa_lock;
+extern int dynamic_enable;
+extern struct kmem_cache *zx_numa_lock_cachep;
+
+static inline u32 ptrmask(void *s)
+{
+ return (uint64_t)s & LOW32MASK;
+}
+inline void *get_numa_lock(int index);
+
+int zx_check_numa_dynamic_locked(u32 lockaddr, struct _numa_lock *_numa_lock,
+ int t);
+int zx_numa_lock_ptr_get(void *p);
+void numa_lock_init_data(struct _numa_lock *s, int clusters, u32 lockval,
+ u32 lockaddr);
+#endif
diff --git a/kernel/locking/numa_osq.h b/kernel/locking/numa_osq.h
new file mode 100644
index 000000000000..4c99ad60c4e0
--- /dev/null
+++ b/kernel/locking/numa_osq.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_NUMA_OSQ_H
+#define __LINUX_NUMA_OSQ_H
+
+#include <linux/osq_lock.h>
+#include "mcs_spinlock.h"
+
+#define OSQLOCKINITED 0
+#define OSQTONUMADETECT 0x10
+#define OSQLOCKSTOPPING 0xfc
+#define OSQ_LOCKED_VAL 0xffff
+
+extern u16 osq_keep_times;
+extern u16 osq_lock_depth;
+extern int osq_node_max;
+
+inline int encode_cpu(int cpu_nr);
+inline int node_cpu(struct optimistic_spin_node *node);
+inline struct optimistic_spin_node *decode_cpu(int encoded_cpu_val);
+
+void zx_osq_lock_stopping(struct optimistic_spin_queue *lock);
+void zx_osq_numa_start(struct optimistic_spin_queue *lock);
+void zx_osq_turn_numa_waiting(struct optimistic_spin_queue *lock);
+
+bool x_osq_lock(struct optimistic_spin_queue *lock);
+void x_osq_unlock(struct optimistic_spin_queue *lock);
+bool x_osq_is_locked(struct optimistic_spin_queue *lock);
+inline void zx_numa_osq_unlock(struct optimistic_spin_queue *qslock,
+ struct _numa_lock *n);
+inline bool zx_numa_osq_lock(struct optimistic_spin_queue *qslock,
+ struct _numa_lock *n);
+#endif
diff --git a/kernel/locking/x_osq_lock.c b/kernel/locking/x_osq_lock.c
new file mode 100644
index 000000000000..6da8905ae7d6
--- /dev/null
+++ b/kernel/locking/x_osq_lock.c
@@ -0,0 +1,332 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * crossing from osq_lock to numa-aware lock
+ */
+#include <linux/percpu.h>
+#include <linux/sched.h>
+#include <linux/osq_lock.h>
+#include "numa.h"
+#include "numa_osq.h"
+
+u16 osq_lock_depth = 8;
+u16 osq_keep_times = 32;
+
+/*
+ * An MCS like lock especially tailored for optimistic spinning for sleeping
+ * lock implementations (mutex, rwsem, etc).
+ *
+ * Using a single mcs node per CPU is safe because sleeping locks should not be
+ * called from interrupt context and we have preemption disabled while
+ * spinning.
+ */
+DECLARE_PER_CPU_SHARED_ALIGNED(struct optimistic_spin_node, osq_node);
+
+/*
+ * Get a stable @node->next pointer, either for unlock() or unqueue() purposes.
+ * Can return NULL in case we were the last queued and we updated @lock instead.
+ *
+ * If osq_lock() is being cancelled there must be a previous node
+ * and 'old_cpu' is its CPU #.
+ * For osq_unlock() there is never a previous node and old_cpu is
+ * set to OSQ_UNLOCKED_VAL.
+ */
+static inline struct optimistic_spin_node *
+osq_wait_next_stop(struct optimistic_spin_queue *lock,
+ struct optimistic_spin_node *node,
+ int old_cpu)
+{
+ u16 curr = encode_cpu(smp_processor_id());
+ u16 old = old_cpu;
+
+ if (lock->numa_enable == OSQLOCKSTOPPING && old == OSQ_UNLOCKED_VAL)
+ old = OSQ_LOCKED_VAL;
+
+ for (;;) {
+ if (READ_ONCE(lock->tail16) == curr &&
+ cmpxchg(&lock->tail16, curr, old) == curr) {
+
+ /*
+ * We were the last queued, we moved @lock back. @prev
+ * will now observe @lock and will complete its
+ * unlock()/unqueue().
+ */
+ return NULL;
+ }
+
+ /*
+ * We must xchg() the @node->next value, because if we were to
+ * leave it in, a concurrent unlock()/unqueue() from
+ * @node->next might complete Step-A and think its @prev is
+ * still valid.
+ *
+ * If the concurrent unlock()/unqueue() wins the race, we'll
+ * wait for either @lock to point to us, through its Step-B, or
+ * wait for a new @node->next from its Step-C.
+ */
+ if (node->next) {
+ struct optimistic_spin_node *next;
+
+ next = xchg(&node->next, NULL);
+ if (next)
+ return next;
+ }
+
+ cpu_relax();
+ }
+}
+
+bool x_osq_lock(struct optimistic_spin_queue *lock)
+{
+ struct optimistic_spin_node *node = this_cpu_ptr(&osq_node);
+ struct optimistic_spin_node *prev, *next;
+ int cpu = smp_processor_id();
+ u16 curr = encode_cpu(cpu);
+ struct optimistic_spin_queue tail;
+ u16 old;
+
+ tail.val = READ_ONCE(lock->val);
+ if (unlikely(tail.numa_enable == OSQLOCKSTOPPING)) {
+ zx_osq_turn_numa_waiting(lock);
+ return x_osq_lock(lock);
+ }
+
+ if (unlikely(tail.numa_enable == NUMALOCKDYNAMIC)) {
+ struct _numa_lock *_numa_lock = NULL;
+ struct _numa_lock *node_lock = NULL;
+
+ _numa_lock = get_numa_lock(tail.index);
+ node_lock = (struct _numa_lock *) _numa_lock +
+ (cpu >> NUMASHIFT);
+
+ prefetch(node_lock);
+ return zx_numa_osq_lock(lock, _numa_lock);
+ }
+
+ node->locked = 0;
+ node->next = NULL;
+ node->cpu = curr;
+
+ /*
+ * We need both ACQUIRE (pairs with corresponding RELEASE in
+ * unlock() uncontended, or fastpath) and RELEASE (to publish
+ * the node fields we just initialised) semantics when updating
+ * the lock tail.
+ */
+
+ if (likely(tail.numa_enable >= OSQTONUMADETECT)) {
+ struct optimistic_spin_queue ss;
+
+ while (1) {
+ ss.val = atomic_read(&lock->tail);
+ if (ss.tail16 == OSQ_LOCKED_VAL) {
+ zx_osq_turn_numa_waiting(lock);
+ return x_osq_lock(lock);
+ }
+ if (cmpxchg(&lock->tail16, ss.tail16, curr)
+ == ss.tail16) {
+ old = ss.tail16;
+ break;
+ }
+ cpu_relax();
+ }
+ } else
+ old = xchg(&lock->tail16, curr);
+
+ if (old == OSQ_UNLOCKED_VAL) {
+ node->serial = 1;
+ return true;
+ }
+
+ prev = decode_cpu(old);
+ node->prev = prev;
+
+ node->serial = prev->serial + 1;
+ /*
+ * osq_lock() unqueue
+ *
+ * node->prev = prev osq_wait_next()
+ * WMB MB
+ * prev->next = node next->prev = prev // unqueue-C
+ *
+ * Here 'node->prev' and 'next->prev' are the same variable and we need
+ * to ensure these stores happen in-order to avoid corrupting the list.
+ */
+ smp_wmb();
+
+ WRITE_ONCE(prev->next, node);
+
+ /*
+ * Normally @prev is untouchable after the above store; because at that
+ * moment unlock can proceed and wipe the node element from stack.
+ *
+ * However, since our nodes are static per-cpu storage, we're
+ * guaranteed their existence -- this allows us to apply
+ * cmpxchg in an attempt to undo our queueing.
+ */
+
+ /*
+ * Wait to acquire the lock or cancellation. Note that need_resched()
+ * will come with an IPI, which will wake smp_cond_load_relaxed() if it
+ * is implemented with a monitor-wait. vcpu_is_preempted() relies on
+ * polling, be careful.
+ */
+ if (smp_cond_load_relaxed(&node->locked, VAL || need_resched() ||
+ vcpu_is_preempted(node_cpu(node->prev))))
+ return true;
+
+ /* unqueue */
+ /*
+ * Step - A -- stabilize @prev
+ *
+ * Undo our @prev->next assignment; this will make @prev's
+ * unlock()/unqueue() wait for a next pointer since @lock points to us
+ * (or later).
+ */
+
+ for (;;) {
+ /*
+ * cpu_relax() below implies a compiler barrier which would
+ * prevent this comparison being optimized away.
+ */
+ if (data_race(prev->next) == node &&
+ cmpxchg(&prev->next, node, NULL) == node)
+ break;
+
+ /*
+ * We can only fail the cmpxchg() racing against an unlock(),
+ * in which case we should observe @node->locked becoming
+ * true.
+ */
+ if (smp_load_acquire(&node->locked))
+ return true;
+
+ cpu_relax();
+
+ /*
+ * Or we race against a concurrent unqueue()'s step-B, in which
+ * case its step-C will write us a new @node->prev pointer.
+ */
+ prev = READ_ONCE(node->prev);
+ }
+
+ /*
+ * Step - B -- stabilize @next
+ *
+ * Similar to unlock(), wait for @node->next or move @lock from @node
+ * back to @prev.
+ */
+
+ next = osq_wait_next_stop(lock, node, prev->cpu);
+ if (!next)
+ return false;
+
+ /*
+ * Step - C -- unlink
+ *
+ * @prev is stable because its still waiting for a new @prev->next
+ * pointer, @next is stable because our @node->next pointer is NULL and
+ * it will wait in Step-A.
+ */
+
+ WRITE_ONCE(next->prev, prev);
+ WRITE_ONCE(prev->next, next);
+
+ return false;
+}
+
+
+
+void x_osq_unlock(struct optimistic_spin_queue *lock)
+{
+ struct optimistic_spin_node *node, *next;
+ int threadshold = osq_lock_depth;
+ int cpu = smp_processor_id();
+ u16 curr = encode_cpu(cpu);
+ int depth = 0;
+ u32 count = 0;
+
+ if (unlikely(lock->numa_enable == NUMALOCKDYNAMIC)) {
+ struct _numa_lock *_numa_lock = get_numa_lock(lock->index);
+
+ prefetch((struct _numa_lock *) _numa_lock + (cpu >> NUMASHIFT));
+ return zx_numa_osq_unlock(lock, _numa_lock);
+ }
+ /*
+ * Fast path for the uncontended case.
+ */
+ if (unlikely(lock->numa_enable == OSQTONUMADETECT)) {
+ struct optimistic_spin_node *node_last = NULL;
+ u16 tail = 0;
+
+ tail = cmpxchg(&lock->tail16, curr, OSQ_UNLOCKED_VAL);
+ if (tail == curr)
+ return;
+
+ node = this_cpu_ptr(&osq_node);
+ node_last = decode_cpu(tail);
+ depth = node_last->serial - node->serial;
+ count = READ_ONCE(node->locked);
+ if (count > osq_keep_times && (dynamic_enable & 0x1))
+ zx_osq_lock_stopping(lock);
+ } else if (unlikely(lock->numa_enable == OSQLOCKSTOPPING)) {
+ if (cmpxchg(&lock->tail16, curr, OSQ_LOCKED_VAL)
+ == curr) {
+ zx_osq_numa_start(lock);
+ return;
+ }
+ } else {
+ struct optimistic_spin_queue t;
+
+ t.val = 0;
+ if (dynamic_enable & 0x1) {
+ if (atomic_read(&numa_count) < zx_numa_lock_total)
+ t.numa_enable = OSQTONUMADETECT;
+ }
+ if (t.numa_enable == OSQTONUMADETECT) {
+ if (atomic_cmpxchg_release(&lock->tail, curr,
+ (t.val | OSQ_UNLOCKED_VAL)) == curr)
+ return;
+ } else if (cmpxchg(&lock->tail16, curr,
+ OSQ_UNLOCKED_VAL) == curr)
+ return;
+ }
+
+ /*
+ * Second most likely case.
+ */
+ node = this_cpu_ptr(&osq_node);
+ next = xchg(&node->next, NULL);
+ if (next) {
+ if (depth > threadshold)
+ WRITE_ONCE(next->locked, count + 1);
+ else
+ WRITE_ONCE(next->locked, 1);
+ return;
+ }
+
+ next = osq_wait_next_stop(lock, node, OSQ_UNLOCKED_VAL);
+ if (next) {
+ if (depth > threadshold)
+ WRITE_ONCE(next->locked, count + 1);
+ else
+ WRITE_ONCE(next->locked, 1);
+ }
+}
+
+bool x_osq_is_locked(struct optimistic_spin_queue *lock)
+{
+ struct optimistic_spin_queue val;
+
+ val.val = atomic_read(&lock->tail);
+ if (val.tail16 == OSQ_UNLOCKED_VAL)
+ return false;
+
+ if (val.tail16 == OSQ_LOCKED_VAL) {
+ if (val.numa_enable != NUMALOCKDYNAMIC)
+ return true;
+ return zx_check_numa_dynamic_locked(ptrmask(lock),
+ get_numa_lock(val.index), 0);
+ }
+
+ return true;
+}
These functions are mostly based on the osq_* functions with some extra
code stuffed in. Common code should be shared instead of duplicated.
diff --git a/kernel/locking/zx_numa_osq.c b/kernel/locking/zx_numa_osq.c
new file mode 100644
index 000000000000..f4c3dba208d3
--- /dev/null
+++ b/kernel/locking/zx_numa_osq.c
@@ -0,0 +1,433 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Dynamic numa-aware osq lock
+ * Author: LiYong <yongli-oc@xxxxxxxxxxx>
+ *
+ */
+#include <linux/cpumask.h>
+#include <asm/byteorder.h>
+#include <linux/percpu.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/osq_lock.h>
+#include "numa.h"
+#include "numa_osq.h"
+
+int osq_node_max = 256;
+
+/*
+ * The pending bit spinning loop count.
+ * This heuristic is used to limit the number of lockword accesses
+ * made by atomic_cond_read_relaxed when waiting for the lock to
+ * transition out of the "== _Q_PENDING_VAL" state. We don't spin
+ * indefinitely because there's no guarantee that we'll make forward
+ * progress.
+ */
+
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct optimistic_spin_node, osq_cpu_node);
+
+/*
+ * We use the value 0 to represent "no CPU", thus the encoded value
+ * will be the CPU number incremented by 1.
+ */
+static inline int decode(int cpu_nr)
+{
+ return cpu_nr - 1;
+}
+
+static inline struct optimistic_spin_node *decode_curr(int encoded_cpu_val)
+{
+ int cpu_nr = decode(encoded_cpu_val);
+
+ return per_cpu_ptr(&osq_cpu_node, cpu_nr);
+}
+
+static int atomic64_cmpxchg_notequal(void *qslock, atomic_t *tail, int curr)
+{
+ u64 ss = 0;
+ u32 addr = ptrmask(qslock);
+ u64 addrcurr = (((u64)addr) << 32) | curr;
+
+ while (1) {
+ ss = atomic64_read((atomic64_t *) tail);
+ if ((ss >> 32) != addr)
+ return NUMA_LOCKED_VAL;
+ if ((ss & LOW32MASK) == NUMA_LOCKED_VAL)
+ return NUMA_LOCKED_VAL;
+ if (atomic64_cmpxchg((atomic64_t *) tail, ss, addrcurr) == ss)
+ return ss & LOW32MASK;
+ cpu_relax();
+ }
+}
+
+void zx_osq_lock_stopping(struct optimistic_spin_queue *lock)
+{
+ int s = 0;
+
+ s = zx_numa_lock_ptr_get(lock);
+ if (s < zx_numa_lock_total) {
+ numa_lock_init_data(zx_numa_entry[s].numa_ptr,
+ NUMACLUSTERS, NUMA_UNLOCKED_VAL,
+ ptrmask(lock));
+
+ WRITE_ONCE(lock->index, s);
+ zx_numa_entry[s].type = 1;
+ smp_mb();/*should set these before enable*/
+ prefetchw(&lock->numa_enable);
+ WRITE_ONCE(lock->numa_enable, OSQLOCKSTOPPING);
+ } else {
+ prefetchw(&lock->numa_enable);
+ WRITE_ONCE(lock->numa_enable, OSQLOCKINITED);
+ }
+}
+
+void zx_osq_numa_start(struct optimistic_spin_queue *lock)
+{
+ struct _numa_lock *_numa_lock = get_numa_lock(lock->index);
+
+ prefetchw(&lock->numa_enable);
+ WRITE_ONCE(lock->numa_enable, NUMALOCKDYNAMIC);
+ smp_mb(); /*should keep lock->numa_enable modified first*/
+ atomic_set(&_numa_lock->initlock, TURNTONUMAREADY);
+}
+
+
+void zx_osq_turn_numa_waiting(struct optimistic_spin_queue *lock)
+{
+ struct _numa_lock *_numa_lock = get_numa_lock(lock->index);
+
+ atomic_inc(&_numa_lock->pending);
+ while (1) {
+ int s = atomic_read(&_numa_lock->initlock);
+
+ if (s == TURNTONUMAREADY)
+ break;
+ cpu_relax();
+ cpu_relax();
+ cpu_relax();
+ cpu_relax();
We don't usually call cpu_relax() multiple times like that as the actual
delay is CPU dependent and it is hard to get it right for all. Can you
explain why it is called exactly 4 times here?
+
+ }
+ atomic_dec(&_numa_lock->pending);
+}
+
+
+
+
+static struct optimistic_spin_node *
+zx_numa_osq_wait_next(struct _numa_lock *lock,
+ struct optimistic_spin_node *node,
+ struct optimistic_spin_node *prev, int cpu)
+{
+ struct optimistic_spin_node *next = NULL;
+ int curr = encode_cpu(cpu);
+ int old;
+
+ old = prev ? prev->cpu : OSQ_UNLOCKED_VAL;
+ for (;;) {
+ if (atomic_read(&lock->tail) == curr &&
+ atomic_cmpxchg_acquire(&lock->tail, curr, old) == curr) {
+
+ break;
+ }
+ if (node->next) {
+ next = xchg(&node->next, NULL);
+ if (next)
+ break;
+ }
+ cpu_relax();
+ }
+ return next;
+}
+static void zx_numa_turn_osq_waiting(struct optimistic_spin_queue *lock,
+ struct _numa_lock *_numa_lock)
+{
+ struct _numa_lock *numa_lock = _numa_lock + _numa_lock->numa_nodes;
+ int lockaddr = ptrmask(lock);
+ u64 s = 0;
+ struct optimistic_spin_queue tail;
+
+ tail.numa_enable = NUMALOCKDYNAMIC;
+ tail.index = lock->index;
+ tail.tail16 = OSQ_LOCKED_VAL;
+ while (1) {
+ cpu_relax(); cpu_relax(); cpu_relax(); cpu_relax();
+ s = atomic64_read((atomic64_t *) &numa_lock->tail);
+ if ((s >> 32) != lockaddr)
+ break;
+ if ((s & LOW32MASK) == NUMA_LOCKED_VAL)
+ break;
+ }
+ prefetchw(&lock->tail);
+ if (atomic_cmpxchg(&lock->tail, tail.val, OSQ_UNLOCKED_VAL)
+ == tail.val) {
+ ;
+ }
+
+}
+
+static int _zx_node_osq_lock_internal(struct optimistic_spin_queue *qslock,
+ struct optimistic_spin_node *node, struct optimistic_spin_node *prev,
+ struct _numa_lock *node_lock, int cpu, int *cur_status)
+{
+ struct optimistic_spin_node *next = NULL;
+
+ for (;;) {
+ struct optimistic_spin_node *node_prev = NULL;
+
+ if (prev->next == node &&
+ cmpxchg(&prev->next, node, NULL) == node) {
+ break;
+ }
+ /*load locked first each time*/
+ *cur_status = smp_load_acquire(&node->locked);
+
+ if (*cur_status != NODE_WAIT)
+ return 0; //goto NODE_UNLOCK;
+
+ cpu_relax();
+ node_prev = READ_ONCE(node->prev);
+ if (node_prev != prev)
+ prev = node_prev;
+ }
+
+ next = zx_numa_osq_wait_next(node_lock, node, prev, cpu);
+ if (!next)
+ return -1;
+
+ WRITE_ONCE(next->prev, prev);
+ WRITE_ONCE(prev->next, next);
+
+ return -1;
+}
+
+static int _zx_node_osq_lock(struct optimistic_spin_queue *qslock,
+ struct _numa_lock *_numa_lock)
+{
+ struct optimistic_spin_node *node = this_cpu_ptr(&osq_cpu_node);
+ struct optimistic_spin_node *prev = NULL;
+ int cpu = smp_processor_id();
+ int curr = encode_cpu(cpu);
+ int numa = cpu >> _numa_lock->shift;
+ struct _numa_lock *node_lock = _numa_lock + numa;
+ int cur_status = 0;
+ int old = 0;
+
+ node->locked = NODE_WAIT;
+ node->next = NULL;
+ node->cpu = curr;
+
+ old = atomic64_cmpxchg_notequal(qslock, &node_lock->tail, curr);
+
+ if (old == NUMA_LOCKED_VAL) {
+ bool s = true;
+
+ zx_numa_turn_osq_waiting(qslock, _numa_lock);
+ s = osq_lock(qslock);
+ if (s == true)
+ return 1;
+ else
+ return -1;
+ }
+
+ if (old == 0) {
+ node->locked = COHORT_START;
+ return ACQUIRE_NUMALOCK;
+ }
+
+ prev = decode_curr(old);
+ node->prev = prev;
+
+ smp_mb(); /* make sure node set before set pre->next */
+
+ WRITE_ONCE(prev->next, node);
+
+ while ((cur_status = READ_ONCE(node->locked)) == NODE_WAIT) {
+ if (need_resched() || vcpu_is_preempted(node_cpu(node->prev))) {
+ int ddd = _zx_node_osq_lock_internal(qslock, node, prev,
+ node_lock, cpu, &cur_status);
+
+ if (cur_status != NODE_WAIT)
+ goto NODE_UNLOCK;
+ if (ddd == -1)
+ return -1;
+ }
+ cpu_relax();
+ }
+NODE_UNLOCK:
+ if (cur_status == ACQUIRE_NUMALOCK)
+ node->locked = COHORT_START;
+ return cur_status;
+}
+static int _zx_numa_osq_lock(struct optimistic_spin_queue *qslock, int cpu,
+ struct _numa_lock *_numa_lock)
+{
+ int numacpu = cpu >> _numa_lock->shift;
+ int numacurr = encode_cpu(numacpu);
+
+ struct optimistic_spin_node *node = &(_numa_lock + numacpu)->osq_node;
+ struct _numa_lock *numa_lock = _numa_lock + _numa_lock->numa_nodes;
+ struct optimistic_spin_node *prevnode = NULL;
+ int prev = 0;
+
+ node->next = NULL;
+ node->locked = LOCK_NUMALOCK;
+ node->cpu = numacurr;
+
+ prev = atomic_xchg(&numa_lock->tail, numacurr);
+ if (prev == 0) {
+ node->locked = UNLOCK_NUMALOCK;
+ return 0;
+ }
+
+ prevnode = &(_numa_lock + prev - 1)->osq_node;
+ node->prev = prevnode;
+ smp_mb(); /*node->prev should be set before next*/
+ WRITE_ONCE(prevnode->next, node);
+
+ while (READ_ONCE(node->locked) == LOCK_NUMALOCK) {
+ cpu_relax();
+ cpu_relax();
+ cpu_relax();
+ cpu_relax();
+ }
+ return 0;
+}
+inline bool zx_numa_osq_lock(struct optimistic_spin_queue *qslock,
+ struct _numa_lock *_numa_lock)
+{
+ struct _numa_lock *node_lock = NULL;
+ int cpu = smp_processor_id();
+ int numa = cpu >> _numa_lock->shift;
+ int status = 0;
+
+ node_lock = _numa_lock + numa;
+
+ if (node_lock->stopping) {
+ zx_numa_turn_osq_waiting(qslock, _numa_lock);
+ return osq_lock(qslock);
+ }
+
+ status = _zx_node_osq_lock(qslock, _numa_lock);
+ if (status == ACQUIRE_NUMALOCK)
+ status = _zx_numa_osq_lock(qslock, smp_processor_id(),
+ _numa_lock);
+
+ if (status == -1)
+ return false;
+ return true;
+}
+
+static int atomic64_checktail_osq(struct optimistic_spin_queue *qslock,
+ struct _numa_lock *node_lock, int ctail)
+{
+ u64 addr = ((u64)ptrmask(qslock)) << 32;
+ u64 addrtail = addr | ctail;
+ u64 ss = 0;
+ bool mark;
+
+ ss = atomic64_read((atomic64_t *) &node_lock->tail);
+ if (node_lock->stopping == 0)
+ mark = (ss == addrtail &&
+ atomic64_cmpxchg_acquire(
+ (atomic64_t *) &node_lock->tail,
+ addrtail, addr|NUMA_UNLOCKED_VAL) == addrtail);
+ else
+ mark = (ss == addrtail &&
+ atomic64_cmpxchg_acquire(
+ (atomic64_t *) &node_lock->tail,
+ addrtail, NUMA_LOCKED_VAL) == addrtail);
+ return mark;
+}
+
+static void node_lock_release(struct optimistic_spin_queue *qslock,
+ struct _numa_lock *node_lock, struct optimistic_spin_node *node,
+ int val, int cpu, int numa_end)
+{
+ struct optimistic_spin_node *next = NULL;
+ int curr = encode_cpu(cpu);
+
+ while (1) {
+ if (atomic64_checktail_osq(qslock, node_lock, curr)) {
+ if (qslock->numa_enable == NUMALOCKDYNAMIC) {
+ int index = qslock->index;
+
+ if (numa_end == OSQ_UNLOCKED_VAL &&
+ zx_numa_entry[index].idle == 0) {
+ cmpxchg(&zx_numa_entry[index].idle,
+ 0, 1);
+ }
+ }
+ return;
+ }
+ if (node->next) {
+ next = xchg(&node->next, NULL);
+ if (next) {
+ WRITE_ONCE(next->locked, val);
+ return;
+ }
+ }
+ cpu_relax();
+ }
+}
+
+static int numa_lock_release(struct optimistic_spin_queue *qslock,
+ struct _numa_lock *numa_lock,
+ struct optimistic_spin_node *node, int cpu)
+{
+ struct optimistic_spin_node *next = NULL;
+ int curr = cpu >> numa_lock->shift;
+ int numacurr = encode_cpu(curr);
+
+ while (1) {
+ if (atomic_read(&numa_lock->tail) == numacurr &&
+ atomic_cmpxchg_acquire(&numa_lock->tail, numacurr,
+ OSQ_UNLOCKED_VAL) == numacurr) {
+ return OSQ_UNLOCKED_VAL;
+ }
+
+ if (node->next) {
+ next = xchg(&node->next, NULL);
+ if (next) {
+ WRITE_ONCE(next->locked, UNLOCK_NUMALOCK);
+ return 1;
+ }
+ }
+ cpu_relax();
+ }
+}
+
+inline void zx_numa_osq_unlock(struct optimistic_spin_queue *qslock,
+ struct _numa_lock *_numa_lock)
+{
+ u32 cpu = smp_processor_id();
+ struct optimistic_spin_node *node = this_cpu_ptr(&osq_cpu_node);
+ int numa = cpu >> _numa_lock->shift;
+ struct _numa_lock *numa_lock = _numa_lock + _numa_lock->numa_nodes;
+ struct _numa_lock *node_lock = _numa_lock + numa;
+ struct optimistic_spin_node *numa_node =
+ &(_numa_lock + numa)->osq_node;
+ struct optimistic_spin_node *next = NULL;
+ int cur_count = 0;
+ int numa_end = 0;
+
+ cur_count = READ_ONCE(node->locked);
+
+ if (cur_count >= osq_node_max - 1) {
+ numa_end = numa_lock_release(qslock,
+ numa_lock, numa_node, cpu);
+ node_lock_release(qslock, node_lock, node,
+ ACQUIRE_NUMALOCK, cpu, numa_end);
+ return;
+ }
+
+ next = xchg(&node->next, NULL);
+ if (next) {
+ WRITE_ONCE(next->locked, cur_count + 1);
+ return;
+ }
+
+ numa_end = numa_lock_release(qslock, numa_lock, numa_node, cpu);
+ node_lock_release(qslock, node_lock, node, ACQUIRE_NUMALOCK,
+ cpu, numa_end);
+}
Overall speaking, there are not enough comments to explain exactly what
are you trying to achieve with these new functions. It makes them hard
to review.
Cheers,
Longman