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Message-ID: <c3c6dbab-3bcc-459d-b32c-4d1c432e39f0@zhaoxin.com>
Date: Thu, 19 Sep 2024 17:32:31 +0800
From: yongli-os <yongli-oc@...oxin.com>
To: Waiman Long <longman@...hat.com>, <peterz@...radead.org>,
<mingo@...hat.com>, <will@...nel.org>, <boqun.feng@...il.com>
CC: <linux-kernel@...r.kernel.org>, <yongli@...oxin.com>,
<louisqi@...oxin.com>, <cobechen@...oxin.com>, <jiangbowang@...oxin.com>
Subject: Re: [PATCH 2/4] locking/osq_lock: Turn to dynamic switch function
from osq_lock/unlock.
On 2024/9/15 00:06, Waiman Long wrote:
>
>
> [这封邮件来自外部发件人 谨防风险]
>
> On 9/14/24 04:53, yongli-oc wrote:
>> To support numa-aware osq lock, the struct optimistic_spin_queue
>> is accessed as three members, numa_enable, index, tail16, by union.
>> The size of the struct is the same as before.
>> If dynamic numa-ware lock enable, turns to the crossing, x_osq_lock to
>> check contention level and starts dynamic switch.
>>
>> Signed-off-by: yongli-oc <yongli-oc@...oxin.com>
>> ---
>> include/linux/osq_lock.h | 33 ++++++++++++++++++++-
>> kernel/locking/osq_lock.c | 62 +++++++++++++++++++++++++++++++++++++--
>> 2 files changed, 91 insertions(+), 4 deletions(-)
>>
>> diff --git a/include/linux/osq_lock.h b/include/linux/osq_lock.h
>> index ea8fb31379e3..37a7bc4ab530 100644
>> --- a/include/linux/osq_lock.h
>> +++ b/include/linux/osq_lock.h
>> @@ -12,14 +12,42 @@ struct optimistic_spin_queue {
>> * Stores an encoded value of the CPU # of the tail node in the
>> queue.
>> * If the queue is empty, then it's set to OSQ_UNLOCKED_VAL.
>> */
>> +#ifdef CONFIG_LOCK_SPIN_ON_OWNER_NUMA
>> + union {
>> + atomic_t tail;
>> + u32 val;
>> +#ifdef __LITTLE_ENDIAN
>> + struct {
>> + u16 tail16;
>> + u8 index;
>> + u8 numa_enable;
>> + };
>> +#else
>> + struct {
>> + u8 numa_enable;
>> + u8 index;
>> + u16 tail16;
>> + };
>> +#endif
>> + };
>> +#else
>> atomic_t tail;
>> +#endif
>> };
>>
>> #define OSQ_UNLOCKED_VAL (0)
>>
>> /* Init macro and function. */
>> +#ifdef CONFIG_LOCK_SPIN_ON_OWNER_NUMA
>> +
>> +#define OSQ_LOCK_UNLOCKED { .tail = ATOMIC_INIT(OSQ_UNLOCKED_VAL) }
>> +
>> +#else
>> +
>> #define OSQ_LOCK_UNLOCKED { ATOMIC_INIT(OSQ_UNLOCKED_VAL) }
>>
>> +#endif
>> +
>> static inline void osq_lock_init(struct optimistic_spin_queue *lock)
>> {
>> atomic_set(&lock->tail, OSQ_UNLOCKED_VAL);
>> @@ -28,9 +56,12 @@ static inline void osq_lock_init(struct
>> optimistic_spin_queue *lock)
>> extern bool osq_lock(struct optimistic_spin_queue *lock);
>> extern void osq_unlock(struct optimistic_spin_queue *lock);
>>
>> +#ifdef CONFIG_LOCK_SPIN_ON_OWNER_NUMA
>> +extern bool osq_is_locked(struct optimistic_spin_queue *lock);
>> +#else
>> static inline bool osq_is_locked(struct optimistic_spin_queue *lock)
>> {
>> return atomic_read(&lock->tail) != OSQ_UNLOCKED_VAL;
>> }
>> -
>> +#endif
>> #endif
>> diff --git a/kernel/locking/osq_lock.c b/kernel/locking/osq_lock.c
>> index 75a6f6133866..a7b516939e00 100644
>> --- a/kernel/locking/osq_lock.c
>> +++ b/kernel/locking/osq_lock.c
>> @@ -2,7 +2,10 @@
>> #include <linux/percpu.h>
>> #include <linux/sched.h>
>> #include <linux/osq_lock.h>
>> -
>> +#ifdef CONFIG_LOCK_SPIN_ON_OWNER_NUMA
>> +#include "numa.h"
>> +#include "numa_osq.h"
>> +#endif
>
> These header files are defined in patch 3. You need to rethink about
> patch ordering in order not to break bisection.
I will move it to the patch 2.
>
>> /*
>> * An MCS like lock especially tailored for optimistic spinning for
>> sleeping
>> * lock implementations (mutex, rwsem, etc).
>> @@ -12,12 +15,34 @@
>> * spinning.
>> */
>>
>> +#ifdef CONFIG_LOCK_SPIN_ON_OWNER_NUMA
>> +DEFINE_PER_CPU_SHARED_ALIGNED(struct optimistic_spin_node, osq_node);
>> +/*
>> + * We use the value 0 to represent "no CPU", thus the encoded value
>> + * will be the CPU number incremented by 1.
>> + */
>> +inline int encode_cpu(int cpu_nr)
>> +{
>> + return cpu_nr + 1;
>> +}
>> +
>> +inline int node_cpu(struct optimistic_spin_node *node)
>> +{
>> + return node->cpu - 1;
>> +}
>> +
>> +inline struct optimistic_spin_node *decode_cpu(int encoded_cpu_val)
>> +{
>> + int cpu_nr = encoded_cpu_val - 1;
>> +
>> + return per_cpu_ptr(&osq_node, cpu_nr);
>> +}
>> +#else
>> struct optimistic_spin_node {
>> struct optimistic_spin_node *next, *prev;
>> int locked; /* 1 if lock acquired */
>> int cpu; /* encoded CPU # + 1 value */
>> };
>> -
>> static DEFINE_PER_CPU_SHARED_ALIGNED(struct optimistic_spin_node,
>> osq_node);
>>
>> /*
>> @@ -40,6 +65,7 @@ static inline struct optimistic_spin_node
>> *decode_cpu(int encoded_cpu_val)
>>
>> return per_cpu_ptr(&osq_node, cpu_nr);
>> }
>> +#endif
>>
>> /*
>> * Get a stable @node->next pointer, either for unlock() or
>> unqueue() purposes.
>> @@ -97,6 +123,14 @@ bool osq_lock(struct optimistic_spin_queue *lock)
>> int curr = encode_cpu(smp_processor_id());
>> int old;
>>
>> +#ifdef CONFIG_LOCK_SPIN_ON_OWNER_NUMA
>> + if (unlikely(enable_zx_numa_osq_lock > 1)) {
>> + node->numa = 1;
>> + return x_osq_lock(lock);
>> + }
>> + node->numa = 0;
>> +#endif
>> +
>> node->locked = 0;
>> node->next = NULL;
>> node->cpu = curr;
>> @@ -108,6 +142,11 @@ bool osq_lock(struct optimistic_spin_queue *lock)
>> * the lock tail.
>> */
>> old = atomic_xchg(&lock->tail, curr);
>> +#ifdef CONFIG_LOCK_SPIN_ON_OWNER_NUMA
>> + if (enable_zx_numa_osq_lock > 0)
>> + //enable means all cpu cores are less tan 65534.
>> + old = old & 0xffff;
>> +#endif
>> if (old == OSQ_UNLOCKED_VAL)
>> return true;
>>
>> @@ -212,6 +251,14 @@ void osq_unlock(struct optimistic_spin_queue *lock)
>> struct optimistic_spin_node *node, *next;
>> int curr = encode_cpu(smp_processor_id());
>>
>> + node = this_cpu_ptr(&osq_node);
>> +
>> +#ifdef CONFIG_LOCK_SPIN_ON_OWNER_NUMA
>> + if (unlikely(enable_zx_numa_osq_lock > 1 &&
>> + node->numa == 1))
>> + return x_osq_unlock(lock);
>> +#endif
>> +
>> /*
>> * Fast path for the uncontended case.
>> */
>> @@ -222,7 +269,6 @@ void osq_unlock(struct optimistic_spin_queue *lock)
>> /*
>> * Second most likely case.
>> */
>> - node = this_cpu_ptr(&osq_node);
>> next = xchg(&node->next, NULL);
>> if (next) {
>> WRITE_ONCE(next->locked, 1);
>> @@ -233,3 +279,13 @@ void osq_unlock(struct optimistic_spin_queue *lock)
>> if (next)
>> WRITE_ONCE(next->locked, 1);
>> }
>> +#ifdef CONFIG_LOCK_SPIN_ON_OWNER_NUMA
>> +bool osq_is_locked(struct optimistic_spin_queue *lock)
>> +{
>> + if (unlikely(enable_zx_numa_osq_lock > 1))
>> + return x_osq_is_locked(lock);
>> + return atomic_read(&lock->tail) != OSQ_UNLOCKED_VAL;
>> +}
>> +#endif
>> +
>> +
>
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