|
24 | 24 | *Tests if the lock is free. Returns TRUE if free, FALSE if locked. |
25 | 25 | *This does *not* change the state of the lock. |
26 | 26 | * |
| 27 | + *void SPIN_DELAY(void) |
| 28 | + *Delay operation to occur inside spinlock wait loop. |
| 29 | + * |
27 | 30 | *Note to implementors: there are default implementations for all these |
28 | 31 | *macros at the bottom of the file. Check if your platform can use |
29 | 32 | *these or needs to override them. |
|
63 | 66 | * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group |
64 | 67 | * Portions Copyright (c) 1994, Regents of the University of California |
65 | 68 | * |
66 | | - * $PostgreSQL: pgsql/src/include/storage/s_lock.h,v 1.123 2003/12/23 22:15:07 tgl Exp $ |
| 69 | + * $PostgreSQL: pgsql/src/include/storage/s_lock.h,v 1.124 2003/12/27 20:58:58 tgl Exp $ |
67 | 70 | * |
68 | 71 | *------------------------------------------------------------------------- |
69 | 72 | */ |
@@ -107,14 +110,28 @@ tas(volatile slock_t *lock) |
107 | 110 | { |
108 | 111 | registerslock_t_res=1; |
109 | 112 |
|
| 113 | +/* Use a non-locking test before asserting the bus lock */ |
110 | 114 | __asm__ __volatile__( |
| 115 | +"cmpb$0,%1\n" |
| 116 | +"jne1f\n" |
111 | 117 | "lock\n" |
112 | 118 | "xchgb%0,%1\n" |
| 119 | +"1: \n" |
113 | 120 | :"=q"(_res),"=m"(*lock) |
114 | 121 | :"0"(_res)); |
115 | 122 | return (int)_res; |
116 | 123 | } |
117 | 124 |
|
| 125 | +#defineSPIN_DELAY() spin_delay() |
| 126 | + |
| 127 | +static __inline__void |
| 128 | +spin_delay(void) |
| 129 | +{ |
| 130 | +__asm__ __volatile__( |
| 131 | +" rep; nop\n" |
| 132 | +: : :"memory"); |
| 133 | +} |
| 134 | + |
118 | 135 | #endif/* __i386__ || __x86_64__ */ |
119 | 136 |
|
120 | 137 |
|
@@ -708,6 +725,10 @@ extern inttas_sema(volatile slock_t *lock); |
708 | 725 | #defineS_INIT_LOCK(lock)S_UNLOCK(lock) |
709 | 726 | #endif/* S_INIT_LOCK */ |
710 | 727 |
|
| 728 | +#if !defined(SPIN_DELAY) |
| 729 | +#defineSPIN_DELAY()((void) 0) |
| 730 | +#endif/* SPIN_DELAY */ |
| 731 | + |
711 | 732 | #if !defined(TAS) |
712 | 733 | externinttas(volatileslock_t*lock);/* in port/.../tas.s, or |
713 | 734 | * s_lock.c */ |
|