*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/storage/buffer/Attic/s_lock.c,v 1.7 1998/05/04 23:49:09 scrappy Exp $
+ * $Header: /cvsroot/pgsql/src/backend/storage/buffer/Attic/s_lock.c,v 1.8 1998/06/16 07:18:15 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include <stdio.h>
+#include <sys/time.h>
#include "config.h"
#include "c.h"
/*
* Each time we busy spin we select the next element of this array as the
* number of microseconds to wait. This accomplishes pseudo random back-off.
- * Values are not critical and are weighted to the low end of the range. They
- * were chosen to work even with different select() timer resolutions on
- * different platforms.
- * note: total time to cycle through all 16 entries might be about .1 second.
+ * Values are not critical but 10 milliseconds is a common platform
+ * granularity.
+ * note: total time to cycle through all 16 entries might be about .07 sec.
*/
-int s_spincycle[S_NSPINCYCLE] =
-{0, 0, 0, 1000, 5000, 0, 10000, 3000,
- 0, 10000, 0, 15000, 9000, 21000, 6000, 30000
+#define S_NSPINCYCLE 20
+#define S_MAX_BUSY 500 * S_NSPINCYCLE
+
+int s_spincycle[S_NSPINCYCLE] =
+{ 0, 0, 0, 0, 10000, 0, 0, 0, 10000, 0,
+ 0, 10000, 0, 0, 10000, 0, 10000, 0, 10000, 10000
};
-#if defined(S_LOCK_DEBUG)
/*
- * s_lock(lock) - take a spinlock
- * add intrumentation code to this and define S_LOCK_DEBUG
- * instead of hacking up the macro in s_lock.h
+ * s_lock_stuck(lock) - complain about a stuck spinlock
+ */
+static void
+s_lock_stuck(volatile slock_t *lock, const char *file, const int line)
+{
+ fprintf(stderr,
+ "\nFATAL: s_lock(%08x) at %s:%d, stuck spinlock. Aborting.\n",
+ (unsigned int) lock, file, line);
+ fprintf(stdout,
+ "\nFATAL: s_lock(%08x) at %s:%d, stuck spinlock. Aborting.\n",
+ (unsigned int) lock, file, line);
+ abort();
+}
+
+
+
+/*
+ * s_lock(lock) - take a spinlock with backoff
*/
void
-s_lock(slock_t *lock, char *file, int line)
+s_lock(volatile slock_t *lock, const char *file, const int line)
{
int spins = 0;
struct timeval delay;
delay.tv_sec = 0;
- delay.tv_usec = s_spincycle[spins++ % S_NSPINCYCLE];
+ delay.tv_usec = s_spincycle[spins % S_NSPINCYCLE];
(void) select(0, NULL, NULL, NULL, &delay);
- if (spins > S_MAX_BUSY)
+ if (++spins > S_MAX_BUSY)
{
- /* It's been well over a minute... */
+ /* It's been over a minute... */
s_lock_stuck(lock, file, line);
}
}
}
-#endif /* S_LOCK_DEBUG */
-
-/*
- * s_lock_stuck(lock) - deal with stuck spinlock
- */
-void
-s_lock_stuck(slock_t *lock, char *file, int line)
-{
- fprintf(stderr,
- "\nFATAL: s_lock(%08x) at %s:%d, stuck spinlock. Aborting.\n",
- (unsigned int) lock, file, line);
- fprintf(stdout,
- "\nFATAL: s_lock(%08x) at %s:%d, stuck spinlock. Aborting.\n",
- (unsigned int) lock, file, line);
- abort();
-}
/*
- * Various TAS implementations moved from s_lock.h to avoid redundant
- * definitions of the same routine.
- * RESOLVE: move this to tas.c. Alternatively get rid of tas.[cso] and fold
- * all that into this file.
+ * Various TAS implementations that cannot live in s_lock.h as no inline
+ * definition exists (yet).
+ * In the future, get rid of tas.[cso] and fold it into this file.
*/
-#if defined(linux)
+#if defined(__GNUC__)
/*************************************************************************
- * All the Linux flavors
+ * All the gcc flavors that are not inlined
*/
-#if defined(__alpha)
-int
-tas(slock_t *lock)
-{
- slock_t _res;
-
- __asm__(" ldq $0, %0 \n\
- bne $0, already_set \n\
- ldq_l $0, %0 \n\
- bne $0, already_set \n\
- or $31, 1, $0 \n\
- stq_c $0, %0 \n\
- beq $0, stqc_fail \n\
- success: bis $31, $31, %1 \n\
- mb \n\
- jmp $31, end \n\
- stqc_fail: or $31, 1, $0 \n\
- already_set: bis $0, $0, %1 \n\
- end: nop ": "=m"(*lock), "=r"(_res): :"0");
-
- return (_res != 0);
-}
-#endif /* __alpha */
-
-
-
-#if defined(i386)
-int
-tas(slock_t *lock)
-{
- slock_t _res = 1;
-
- __asm__("lock; xchgb %0,%1": "=q"(_res), "=m"(*lock):"0"(0x1));
- return (_res != 0);
-}
-#endif /* i386 */
-
-
-
-#if defined(sparc)
-
-int
-tas(slock_t *lock)
-{
- slock_t _res;
- slock_t *tmplock = lock;
-
- __asm__("ldstub [%1], %0" \
- : "=&r"(_res), "=r"(tmplock) \
- : "1"(tmplock));
- return (_res != 0);
-}
-
-#endif /* sparc */
-
-
#if defined(PPC)
-
-static int
-tas_dummy()
+/* Note: need a nice gcc constrained asm version so it can be inlined */
+int
+tas(volatile slock_t *lock)
{
- __asm__(" \n\
-tas: \n\
- lwarx 5,0,3 \n\
+ __asm__("lwarx 5,0,3 \n\
cmpwi 5,0 \n\
bne fail \n\
addi 5,5,1 \n\
blr \n\
");
}
-
#endif /* PPC */
-#else /* defined(linux) */
+#else /* defined(__GNUC__) */
/***************************************************************************
- * All Non-Linux
+ * All non gcc
*/
#if defined(sun3)
static void
-tas_dummy() /* really means: extern int tas(slock_t *lock); */
+tas_dummy() /* really means: extern int tas(slock_t *lock); */
{
asm("LLA0:");
asm(" .data");
#if defined(NEED_SPARC_TAS_ASM)
/*
- * bsd and bsdi sparc machines
+ * sparc machines not using gcc
*/
-
-/* if we're using -ansi w/ gcc, use __asm__ instead of asm */
-#if defined(__STRICT_ANSI__)
-#define asm(x) __asm__(x)
-#endif /* __STRICT_ANSI__ */
-
static void
-tas_dummy() /* really means: extern int tas(slock_t *lock); */
+tas_dummy() /* really means: extern int tas(slock_t *lock); */
{
asm(".seg \"data\"");
asm(".seg \"text\"");
asm("_tas:");
-
/*
* Sparc atomic test and set (sparc calls it "atomic load-store")
*/
asm("ldstub [%r8], %r8");
-
asm("retl");
asm("nop");
}
-#if defined(NEED_VAX_TAS_ASM)
-/*
- * VAXen -- even multiprocessor ones
- * (thanks to Tom Ivar Helbekkmo)
- */
-typedef unsigned char slock_t;
-
-int
-tas(slock_t *lock)
-{
- register ret;
-
- asm(" movl $1, r0
- bbssi $0, (%1), 1f
- clrl r0
- 1: movl r0, %0 "
- : "=r"(ret) /* return value, in register */
- : "r"(lock) /* argument, 'lock pointer', in register */
- : "r0"); /* inline code uses this register */
-
- return ret;
-}
-
-#endif /* NEED_VAX_TAS_ASM */
-
-
-
#if defined(NEED_I386_TAS_ASM)
-/*
- * i386 based things
- */
-
-#if defined(USE_UNIVEL_CC)
-asm int
-tas(slock_t *s_lock)
-{
- %lab locked;
-/* Upon entry, %eax will contain the pointer to the lock byte */
- pushl % ebx
- xchgl % eax, %ebx
- xor % eax, %eax
- movb $255, %al
- lock
- xchgb % al, (%ebx)
- popl % ebx
-}
-
-
-#else /* USE_UNIVEL_CC */
-
-int
-tas(slock_t *lock)
-{
- slock_t _res = 1;
+/* non gcc i386 based things */
+#endif /* NEED_I386_TAS_ASM */
- __asm__("lock; xchgb %0,%1": "=q"(_res), "=m"(*lock):"0"(0x1));
- return (_res != 0);
-}
-#endif /* USE_UNIVEL_CC */
-#endif /* NEED_I386_TAS_ASM */
+#endif /* not __GNUC__ */
-#endif /* linux */
+/*****************************************************************************/
#if defined(S_LOCK_TEST)
-slock_t test_lock;
+/*
+ * test program for verifying a port.
+ */
+
+volatile slock_t test_lock;
void
main()
printf("S_LOCK_TEST: this will hang for a few minutes and then abort\n");
printf(" with a 'stuck spinlock' message if S_LOCK()\n");
printf(" and TAS() are working.\n");
- S_LOCK(&test_lock);
+ s_lock(&test_lock, __FILE__, __LINE__);
printf("S_LOCK_TEST: failed, lock not locked~\n");
exit(3);
}
#endif /* S_LOCK_TEST */
+
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/include/storage/s_lock.h,v 1.35 1998/06/15 18:40:04 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/include/storage/s_lock.h,v 1.36 1998/06/16 07:18:16 momjian Exp $
*
*-------------------------------------------------------------------------
*/
+
/*
* DESCRIPTION
- * The public functions that must be provided are:
+ * The public macros that must be provided are:
*
* void S_INIT_LOCK(slock_t *lock)
*
* #define TAS(lock) tas(lock)
* int tas(slock_t *lock) // True if lock already set
*
+ * There are default implementations for all these macros at the bottom
+ * of this file. Check if your platform can use these or needs to
+ * override them.
+ *
+ * NOTES
* If none of this can be done, POSTGRES will default to using
* System V semaphores (and take a large performance hit -- around 40%
* of its time on a DS5000/240 is spent in semop(3)...).
*
- * NOTES
* AIX has a test-and-set but the recommended interface is the cs(3)
* system call. This provides an 8-instruction (plus system call
* overhead) uninterruptible compare-and-set operation. True
* regression test suite by about 25%. I don't have an assembler
* manual for POWER in any case.
*
- * There are default implementations for all these macros at the bottom
- * of this file. Check if your platform can use these or needs to
- * override them.
- *
*/
#if !defined(S_LOCK_H)
#define S_LOCK_H
#if defined(HAS_TEST_AND_SET)
-#if defined(linux)
-/***************************************************************************
- * All Linux
+
+#if defined(__GNUC__)
+/*************************************************************************
+ * All the gcc inlines
*/
#if defined(__alpha)
-
+#define TAS(lock) tas(lock)
#define S_UNLOCK(lock) { __asm__("mb"); *(lock) = 0; }
+static __inline__ int
+tas(volatile slock_t *lock)
+{
+ register slock_t _res;
+
+ __asm__(" ldq $0, %0 \n\
+ bne $0, already_set \n\
+ ldq_l $0, %0 \n\
+ bne $0, already_set \n\
+ or $31, 1, $0 \n\
+ stq_c $0, %0 \n\
+ beq $0, stqc_fail \n\
+ success: bis $31, $31, %1 \n\
+ mb \n\
+ jmp $31, end \n\
+ stqc_fail: or $31, 1, $0 \n\
+ already_set: bis $0, $0, %1 \n\
+ end: nop " : "=m"(*lock), "=r"(_res) : : "0");
+
+ return (int) _res;
+}
#endif /* __alpha */
+#if defined(i386)
+#define TAS(lock) tas(lock)
+
+static __inline__ int
+tas(volatile slock_t *lock)
+{
+ register slock_t _res = 1;
+
+ __asm__("lock; xchgb %0,%1" : "=q"(_res), "=m"(*lock) : "0"(_res) );
+ return (int) _res;
+}
+#endif /* i386 */
+
+
+
+#if defined(sparc)
+#define TAS(lock) tas(lock)
+
+static __inline__ int
+tas(volatile slock_t *lock)
+{
+ register slock_t _res = 1;
+
+ __asm__("ldstub [%1], %0" \
+ : "=r"(_res), "=m"(*lock) \
+ : "1"(lock));
+ return (int) _res;
+}
+#endif /* sparc */
+
+
+
+#if defined(NEED_VAX_TAS_ASM)
+/*
+ * VAXen -- even multiprocessor ones
+ * (thanks to Tom Ivar Helbekkmo)
+ */
+#define TAS(lock) tas(lock)
+
+typedef unsigned char slock_t;
+
+static __inline__ int
+tas(volatile slock_t *lock)
+{
+ register _res;
+
+ __asm__(" movl $1, r0
+ bbssi $0, (%1), 1f
+ clrl r0
+ 1: movl r0, %0 "
+ : "=r"(_res) /* return value, in register */
+ : "r"(lock) /* argument, 'lock pointer', in register */
+ : "r0"); /* inline code uses this register */
+ return (int) _res;
+}
+#endif /* NEED_VAX_TAS_ASM */
+
+
-#else /* linux */
+
+#else /* __GNUC__ */
/***************************************************************************
- * All non Linux
+ * All non gcc
*/
#if defined (nextstep)
*/
#define S_LOCK(lock) mutex_lock(lock)
-
#define S_UNLOCK(lock) mutex_unlock(lock)
-
#define S_INIT_LOCK(lock) mutex_init(lock)
-
/* For Mach, we have to delve inside the entrails of `struct mutex'. Ick! */
#define S_LOCK_FREE(alock) ((alock)->lock == 0)
-
#endif /* nextstep */
* for the R3000 chips out there.
*/
#define TAS(lock) (!acquire_lock(lock))
-
#define S_UNLOCK(lock) release_lock(lock)
-
#define S_INIT_LOCK(lock) init_lock(lock)
-
#define S_LOCK_FREE(lock) (stat_lock(lock) == UNLOCKED)
-
#endif /* __sgi */
* (see storage/ipc.h).
*/
#define TAS(lock) (msem_lock((lock), MSEM_IF_NOWAIT) < 0)
-
#define S_UNLOCK(lock) msem_unlock((lock), 0)
-
#define S_INIT_LOCK(lock) msem_init((lock), MSEM_UNLOCKED)
-
#define S_LOCK_FREE(lock) (!(lock)->msem_state)
-
#endif /* __alpha */
* (see storage/ipc.h).
*/
#define TAS(lock) cs((int *) (lock), 0, 1)
-
#endif /* _AIX */
{-1, -1, -1, -1};
#define S_UNLOCK(lock) (*(lock) = clear_lock) /* struct assignment */
-
#define S_LOCK_FREE(lock) ( *(int *) (((long) (lock) + 15) & ~15) != 0)
-
#endif /* __hpux */
-#endif /* else defined(linux) */
-
+#if defined(NEED_I386_TAS_ASM)
+/* non gcc i386 based things */
+#if defined(USE_UNIVEL_CC)
+#define TAS(lock) tas(lock)
-/****************************************************************************
- * Default Definitions - override these above as needed.
- */
+asm int
+tas(slock_t *s_lock)
+{
+ %lab locked;
+ /* Upon entry, %eax will contain the pointer to the lock byte */
+ pushl % ebx
+ xchgl % eax, %ebx
+ xor % eax, %eax
+ movb $255, %al
+ lock
+ xchgb % al, (%ebx)
+ popl % ebx
+}
+#endif /* USE_UNIVEL_CC */
-#if !defined(S_LOCK)
-#include <sys/time.h>
+#endif /* NEED_I386_TAS_ASM */
-#define S_NSPINCYCLE 16
-#define S_MAX_BUSY 1000 * S_NSPINCYCLE
-extern int s_spincycle[];
-extern void s_lock_stuck(slock_t *lock, char *file, int line);
+#endif /* else defined(__GNUC__) */
-#if defined(S_LOCK_DEBUG)
-extern void s_lock(slock_t *lock);
-#define S_LOCK(lock) s_lock(lock, __FILE__, __LINE__)
-#else /* S_LOCK_DEBUG */
+/****************************************************************************
+ * Default Definitions - override these above as needed.
+ */
+#if !defined(S_LOCK)
+extern void s_lock(volatile slock_t *lock, const char *file, const int line);
#define S_LOCK(lock) \
-do { \
- int spins = 0; \
- while (TAS(lock)) \
- { \
- struct timeval delay; \
- delay.tv_sec = 0; \
- delay.tv_usec = s_spincycle[spins++ % S_NSPINCYCLE]; \
- (void) select(0, NULL, NULL, NULL, &delay); \
- if (spins > S_MAX_BUSY) \
- { \
- /* It's been well over a minute... */ \
- s_lock_stuck(lock, __FILE__, __LINE__); \
- } \
- } \
-} while(0)
-
-#endif /* S_LOCK_DEBUG */
+ if (TAS((volatile slock_t *) lock)) {\
+ s_lock((volatile slock_t *) lock, __FILE__, __LINE__); \
+ } else
#endif /* S_LOCK */
-
-
#if !defined(S_LOCK_FREE)
-#define S_LOCK_FREE(lock) ((*lock) == 0)
+#define S_LOCK_FREE(lock) (*(lock) == 0)
#endif /* S_LOCK_FREE */
#if !defined(S_UNLOCK)
#endif /* S_INIT_LOCK */
#if !defined(TAS)
-int tas(slock_t *lock); /* port/.../tas.s, or s_lock.c */
-
-#define TAS(lock) tas(lock)
+int tas(volatile slock_t *lock); /* port/.../tas.s, or s_lock.c */
+#define TAS(lock) tas((volatile slock_t *) lock)
#endif /* TAS */
#endif /* HAS_TEST_AND_SET */
-
#endif /* S_LOCK_H */
+
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