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ANDROID: vendor_hooks: add hooks in rwsem read trylock

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When the lock is owned by readers and there is no RWSEM_FLAG_HANDOFF set,
we allow some specific new readers to acquire the lock immediately
in this hook, event if there are some writer tasks in the wait_list.
This features can optimize the priority inversion problem caused by
rwsem and improve system responsiveness and
performance.

Bug: 348699619
Bug: 336506800

Change-Id: I7e8fded73579933d1f61faa9fb6e5f300ffd71bf
Signed-off-by: zhujingpeng <zhujingpeng@vivo.com>
[jstultz: rebased, resolved collision]
Signed-off-by: John Stultz <jstultz@google.com>
This commit is contained in:
zhujingpeng
2024-04-23 21:50:15 +08:00
committed by wang qiankun
parent 1a72e2f692
commit e270773646
3 changed files with 22 additions and 0 deletions
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1
drivers/android/vendor_hooks.c
View File

@@ -420,3 +420,4 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_set_tsk_need_resched_lazy);
EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_do_read_fault);
EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_queue_request_and_unlock);
EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_fuse_request_end);
EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_rwsem_read_trylock_failed);

3
include/trace/hooks/rwsem.h
View File

@@ -34,6 +34,9 @@ DECLARE_HOOK(android_vh_rwsem_direct_rsteal,
DECLARE_HOOK(android_vh_rwsem_optimistic_rspin,
TP_PROTO(struct rw_semaphore *sem, long *adjustment, bool *rspin),
TP_ARGS(sem, adjustment, rspin));
DECLARE_HOOK(android_vh_rwsem_read_trylock_failed,
TP_PROTO(struct rw_semaphore *sem, long *cntp, int *ret),
TP_ARGS(sem, cntp, ret));
#endif /* _TRACE_HOOK_RWSEM_H */
/* This part must be outside protection */
#include <trace/define_trace.h>

18
kernel/locking/rwsem.c
View File

@@ -242,6 +242,8 @@ static inline void rwsem_set_nonspinnable(struct rw_semaphore *sem)
static inline bool rwsem_read_trylock(struct rw_semaphore *sem, long *cntp)
{
int ret = 0;
*cntp = atomic_long_add_return_acquire(RWSEM_READER_BIAS, &sem->count);
if (WARN_ON_ONCE(*cntp < 0))
@@ -253,6 +255,13 @@ static inline bool rwsem_read_trylock(struct rw_semaphore *sem, long *cntp)
return true;
}
trace_android_vh_rwsem_read_trylock_failed(sem, cntp, &ret);
if (ret) {
rwsem_set_reader_owned(sem);
trace_android_vh_record_rwsem_lock_starttime(current, jiffies);
return true;
}
return false;
}
@@ -1354,6 +1363,15 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
break;
}
}
if (!ret) {
trace_android_vh_rwsem_read_trylock_failed(sem, NULL, &ret);
if (ret) {
rwsem_set_reader_owned(sem);
trace_android_vh_record_rwsem_lock_starttime(current, jiffies);
}
}
preempt_enable();
return ret;
}