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Rework the optimization for spinlocks on UP to be slightly less drastic and

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turn it back on.  Specifically, the actual changes are now less intrusive
in that the _get_spin_lock() and _rel_spin_lock() macros now have their
contents changed for UP vs SMP kernels which centralizes the changes.
Also, UP kernels do not use _mtx_lock_spin() and no longer include it.  The
UP versions of the spin lock functions do not use any atomic operations,
but simple compares and stores which allow mtx_owned() to still work for
spin locks while removing the overhead of atomic operations.

Tested on:	i386, alpha
This commit is contained in:
jhb 2005-01-05 21:13:27 +00:00
parent 90af8e5e9a
commit 65d4d80800
2 changed files with 28 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
sys/kern/kern_mutex.c
View File

@ -374,11 +374,7 @@ _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line)
m->mtx_object.lo_name, file, line));
WITNESS_CHECKORDER(&m->mtx_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
file, line);
#if defined(SMP) || LOCK_DEBUG > 0 || 1
_get_spin_lock(m, curthread, opts, file, line);
#else
critical_enter();
#endif
LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file,
line);
WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
@ -396,11 +392,7 @@ _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line)
LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file,
line);
mtx_assert(m, MA_OWNED);
#if defined(SMP) || LOCK_DEBUG > 0 || 1
_rel_spin_lock(m);
#else
critical_exit();
#endif
}
/*
@ -573,6 +565,7 @@ _mtx_lock_sleep(struct mtx *m, struct thread *td, int opts, const char *file,
return;
}
#ifdef SMP
/*
* _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock.
*
@ -620,6 +613,7 @@ _mtx_lock_spin(struct mtx *m, struct thread *td, int opts, const char *file,
return;
}
#endif /* SMP */
/*
* _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.

31
sys/sys/mutex.h
View File

@ -103,8 +103,10 @@ void mutex_init(void);
void _mtx_lock_sleep(struct mtx *m, struct thread *td, int opts,
const char *file, int line);
void _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line);
#ifdef SMP
void _mtx_lock_spin(struct mtx *m, struct thread *td, int opts,
const char *file, int line);
#endif
void _mtx_unlock_spin(struct mtx *m, int opts, const char *file, int line);
int _mtx_trylock(struct mtx *m, int opts, const char *file, int line);
void _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line);
@ -161,6 +163,7 @@ void _mtx_assert(struct mtx *m, int what, const char *file, int line);
* a deal.
*/
#ifndef _get_spin_lock
#ifdef SMP
#define _get_spin_lock(mp, tid, opts, file, line) do { \
struct thread *_tid = (tid); \
\
@ -172,6 +175,19 @@ void _mtx_assert(struct mtx *m, int what, const char *file, int line);
_mtx_lock_spin((mp), _tid, (opts), (file), (line)); \
} \
} while (0)
#else /* SMP */
#define _get_spin_lock(mp, tid, opts, file, line) do { \
struct thread *_tid = (tid); \
\
critical_enter(); \
if ((mp)->mtx_lock == (uintptr_t)_tid) \
(mp)->mtx_recurse++; \
else { \
KASSERT((mp)->mtx_lock == MTX_UNOWNED, ("corrupt spinlock")); \
(mp)->mtx_lock = (uintptr_t)_tid; \
} \
} while (0)
#endif /* SMP */
#endif
/*
@ -196,6 +212,7 @@ void _mtx_assert(struct mtx *m, int what, const char *file, int line);
* releasing a spin lock. This includes the recursion cases.
*/
#ifndef _rel_spin_lock
#ifdef SMP
#define _rel_spin_lock(mp) do { \
if (mtx_recursed((mp))) \
(mp)->mtx_recurse--; \
@ -203,6 +220,15 @@ void _mtx_assert(struct mtx *m, int what, const char *file, int line);
_release_lock_quick((mp)); \
critical_exit(); \
} while (0)
#else /* SMP */
#define _rel_spin_lock(mp) do { \
if (mtx_recursed((mp))) \
(mp)->mtx_recurse--; \
else \
(mp)->mtx_lock = MTX_UNOWNED; \
critical_exit(); \
} while (0)
#endif /* SMP */
#endif
/*
@ -283,15 +309,10 @@ extern struct mtx_pool *mtxpool_sleep;
_get_sleep_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
#define mtx_unlock_flags(m, opts) \
_rel_sleep_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
#ifndef SMPnotyet
#define mtx_lock_spin_flags(m, opts) \
_get_spin_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
#define mtx_unlock_spin_flags(m, opts) \
_rel_spin_lock((m))
#else /* SMP */
#define mtx_lock_spin_flags(m, opts) critical_enter()
#define mtx_unlock_spin_flags(m, opts) critical_exit()
#endif /* SMP */
#endif /* LOCK_DEBUG > 0 || MUTEX_NOINLINE */
#define mtx_trylock_flags(m, opts) \