Messages in this thread Patch in this message | | | Date | Fri, 4 May 2001 20:46:16 +0400 | From | Ivan Kokshaysky <> | Subject | Re: [patch] 2.4.4 alpha semaphores optimization |
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On Fri, May 04, 2001 at 10:22:53AM +0100, David Howells wrote: > I don't know whether it will (a) compile, or (b) work... I don't have an alpha > to play with.
Neither (a) nor (b) ;-) Corrected asm-alpha/rwsem.h attached. Also small fix for lib/rwsem.c -- RWSEM_WAITING_BIAS-RWSEM_ACTIVE_BIAS won't fit in the __s32 if counters are 64-bit.
--- linux/lib/rwsem.c.orig Sat Apr 28 00:58:28 2001 +++ linux/lib/rwsem.c Fri May 4 17:38:06 2001 @@ -112,7 +112,7 @@ static inline struct rw_semaphore *__rws */ static inline struct rw_semaphore *rwsem_down_failed_common(struct rw_semaphore *sem, struct rwsem_waiter *waiter, - __s32 adjustment) + signed long adjustment) { struct task_struct *tsk = current; signed long count; Ivan.
#ifndef _ALPHA_RWSEM_H #define _ALPHA_RWSEM_H
/* * Written by Ivan Kokshaysky <ink@jurassic.park.msu.ru>, 2001. * Based on asm-alpha/semaphore.h and asm-i386/rwsem.h */
#ifndef _LINUX_RWSEM_H #error please dont include asm/rwsem.h directly, use linux/rwsem.h instead #endif
#ifdef __KERNEL__
#include <linux/list.h> #include <linux/spinlock.h>
struct rwsem_waiter;
extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem); extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem); extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *);
/* * the semaphore definition */ struct rw_semaphore { long count; #define RWSEM_UNLOCKED_VALUE 0x0000000000000000L #define RWSEM_ACTIVE_BIAS 0x0000000000000001L #define RWSEM_ACTIVE_MASK 0x00000000ffffffffL #define RWSEM_WAITING_BIAS (-0x0000000100000000L) #define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS #define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) spinlock_t wait_lock; struct list_head wait_list; #if RWSEM_DEBUG int debug; #endif };
#if RWSEM_DEBUG #define __RWSEM_DEBUG_INIT , 0 #else #define __RWSEM_DEBUG_INIT /* */ #endif
#define __RWSEM_INITIALIZER(name) \ { RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, \ LIST_HEAD_INIT((name).wait_list) __RWSEM_DEBUG_INIT }
#define DECLARE_RWSEM(name) \ struct rw_semaphore name = __RWSEM_INITIALIZER(name)
static inline void init_rwsem(struct rw_semaphore *sem) { sem->count = RWSEM_UNLOCKED_VALUE; spin_lock_init(&sem->wait_lock); INIT_LIST_HEAD(&sem->wait_list); #if RWSEM_DEBUG sem->debug = 0; #endif }
static inline void __down_read(struct rw_semaphore *sem) { long oldcount, temp; __asm__ __volatile__( "1: ldq_l %0,%1\n" " addq %0,%3,%2\n" " stq_c %2,%1\n" " beq %2,2f\n" #ifdef CONFIG_SMP " mb\n" #endif ".subsection 2\n" "2: br 1b\n" ".previous" :"=&r" (oldcount), "=m" (sem->count), "=&r" (temp) :"Ir" (RWSEM_ACTIVE_READ_BIAS), "m" (sem->count) : "memory");
if (oldcount < 0) rwsem_down_read_failed(sem); }
static inline void __down_write(struct rw_semaphore *sem) { long granted, temp; __asm__ __volatile__( "1: ldq_l %0,%1\n" " addq %0,%3,%2\n" " stq_c %2,%1\n" " beq %2,2f\n" #ifdef CONFIG_SMP " mb\n" #endif " cmpeq %0,0,%0\n" ".subsection 2\n" "2: br 1b\n" ".previous" :"=&r" (granted), "=m" (sem->count), "=&r" (temp) :"Ir" (RWSEM_ACTIVE_WRITE_BIAS), "m" (sem->count) : "memory");
if (!granted) rwsem_down_write_failed(sem); }
static inline void __up_read(struct rw_semaphore *sem) { long oldcount, temp; __asm__ __volatile__( #ifdef CONFIG_SMP " mb\n" #endif "1: ldq_l %0,%1\n" " subq %0,%3,%2\n" " stq_c %2,%1\n" " beq %2,2f\n" ".subsection 2\n" "2: br 1b\n" ".previous" :"=&r" (oldcount), "=m" (sem->count), "=&r" (temp) :"Ir" (RWSEM_ACTIVE_READ_BIAS), "m" (sem->count) : "memory");
if (oldcount < 0) if ((oldcount & RWSEM_ACTIVE_MASK) == 0) rwsem_wake(sem); }
static inline void __up_write(struct rw_semaphore *sem) { long count, cmp; __asm__ __volatile__( #ifdef CONFIG_SMP " mb\n" #endif "1: ldq_l %0,%1\n" " subq %0,%3,%2\n" " stq_c %2,%1\n" " beq %2,2f\n" " cmpeq %0,%3,%2\n" ".subsection 2\n" "2: br 1b\n" ".previous" :"=&r" (count), "=m" (sem->count), "=&r" (cmp) :"Ir" (RWSEM_ACTIVE_WRITE_BIAS), "m" (sem->count) : "memory");
if (!cmp) if ((int)count - RWSEM_ACTIVE_BIAS == 0) rwsem_wake(sem); }
static inline void rwsem_atomic_add(long val, struct rw_semaphore *sem) { long temp; __asm__ __volatile__( "1: ldq_l %0,%1\n" " addq %0,%2,%0\n" " stq_c %0,%1\n" " beq %0,2f\n" ".subsection 2\n" "2: br 1b\n" ".previous" :"=&r" (temp), "=m" (sem->count) :"Ir" (val), "m" (sem->count)); }
static inline long rwsem_atomic_update(long val, struct rw_semaphore *sem) { long temp, ret; __asm__ __volatile__( "1: ldq_l %0,%1\n" " addq %0,%3,%2\n" " addq %0,%3,%0\n" " stq_c %2,%1\n" " beq %2,2f\n" ".subsection 2\n" "2: br 1b\n" ".previous" :"=&r" (ret), "=m" (sem->count), "=&r" (temp) :"Ir" (val), "m" (sem->count));
return ret; }
#endif /* __KERNEL__ */ #endif /* _ALPHA_RWSEM_H */
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