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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2006-10-01 02:27:43 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-10-01 03:39:21 -0400
commitef6edc9746dc2bfdacf44eefd5f881179971c478 (patch)
treee8670e918a852978b2e93e189936f327be072284 /include
parente3e5fc91d9828a9b94a3992de47d47d2d2e34ec6 (diff)
[PATCH] Directed yield: cpu_relax variants for spinlocks and rw-locks
On systems running with virtual cpus there is optimization potential in regard to spinlocks and rw-locks. If the virtual cpu that has taken a lock is known to a cpu that wants to acquire the same lock it is beneficial to yield the timeslice of the virtual cpu in favour of the cpu that has the lock (directed yield). With CONFIG_PREEMPT="n" this can be implemented by the architecture without common code changes. Powerpc already does this. With CONFIG_PREEMPT="y" the lock loops are coded with _raw_spin_trylock, _raw_read_trylock and _raw_write_trylock in kernel/spinlock.c. If the lock could not be taken cpu_relax is called. A directed yield is not possible because cpu_relax doesn't know anything about the lock. To be able to yield the lock in favour of the current lock holder variants of cpu_relax for spinlocks and rw-locks are needed. The new _raw_spin_relax, _raw_read_relax and _raw_write_relax primitives differ from cpu_relax insofar that they have an argument: a pointer to the lock structure. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Mackerras <paulus@samba.org> Cc: Haavard Skinnemoen <hskinnemoen@atmel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include')
-rw-r--r--include/asm-alpha/spinlock.h4
-rw-r--r--include/asm-arm/spinlock.h4
-rw-r--r--include/asm-cris/arch-v32/spinlock.h4
-rw-r--r--include/asm-i386/spinlock.h4
-rw-r--r--include/asm-ia64/spinlock.h4
-rw-r--r--include/asm-m32r/spinlock.h4
-rw-r--r--include/asm-mips/spinlock.h4
-rw-r--r--include/asm-parisc/spinlock.h4
-rw-r--r--include/asm-powerpc/spinlock.h4
-rw-r--r--include/asm-ppc/spinlock.h4
-rw-r--r--include/asm-s390/spinlock.h4
-rw-r--r--include/asm-sh/spinlock.h4
-rw-r--r--include/asm-sparc/spinlock.h4
-rw-r--r--include/asm-sparc64/spinlock.h4
-rw-r--r--include/asm-x86_64/spinlock.h4
15 files changed, 60 insertions, 0 deletions
diff --git a/include/asm-alpha/spinlock.h b/include/asm-alpha/spinlock.h
index 0c294c9b0c55..aeeb125f6851 100644
--- a/include/asm-alpha/spinlock.h
+++ b/include/asm-alpha/spinlock.h
@@ -166,4 +166,8 @@ static inline void __raw_write_unlock(raw_rwlock_t * lock)
166 lock->lock = 0; 166 lock->lock = 0;
167} 167}
168 168
169#define _raw_spin_relax(lock) cpu_relax()
170#define _raw_read_relax(lock) cpu_relax()
171#define _raw_write_relax(lock) cpu_relax()
172
169#endif /* _ALPHA_SPINLOCK_H */ 173#endif /* _ALPHA_SPINLOCK_H */
diff --git a/include/asm-arm/spinlock.h b/include/asm-arm/spinlock.h
index 01b7c26a3038..861092fbaa53 100644
--- a/include/asm-arm/spinlock.h
+++ b/include/asm-arm/spinlock.h
@@ -218,4 +218,8 @@ static inline int __raw_read_trylock(raw_rwlock_t *rw)
218/* read_can_lock - would read_trylock() succeed? */ 218/* read_can_lock - would read_trylock() succeed? */
219#define __raw_read_can_lock(x) ((x)->lock < 0x80000000) 219#define __raw_read_can_lock(x) ((x)->lock < 0x80000000)
220 220
221#define _raw_spin_relax(lock) cpu_relax()
222#define _raw_read_relax(lock) cpu_relax()
223#define _raw_write_relax(lock) cpu_relax()
224
221#endif /* __ASM_SPINLOCK_H */ 225#endif /* __ASM_SPINLOCK_H */
diff --git a/include/asm-cris/arch-v32/spinlock.h b/include/asm-cris/arch-v32/spinlock.h
index 52df72a62232..5f43df0a5fb4 100644
--- a/include/asm-cris/arch-v32/spinlock.h
+++ b/include/asm-cris/arch-v32/spinlock.h
@@ -160,4 +160,8 @@ static __inline__ int is_write_locked(rwlock_t *rw)
160 return rw->counter < 0; 160 return rw->counter < 0;
161} 161}
162 162
163#define _raw_spin_relax(lock) cpu_relax()
164#define _raw_read_relax(lock) cpu_relax()
165#define _raw_write_relax(lock) cpu_relax()
166
163#endif /* __ASM_ARCH_SPINLOCK_H */ 167#endif /* __ASM_ARCH_SPINLOCK_H */
diff --git a/include/asm-i386/spinlock.h b/include/asm-i386/spinlock.h
index b0b3043f05e1..c18b71fae6b3 100644
--- a/include/asm-i386/spinlock.h
+++ b/include/asm-i386/spinlock.h
@@ -205,4 +205,8 @@ static inline void __raw_write_unlock(raw_rwlock_t *rw)
205 : "+m" (rw->lock) : : "memory"); 205 : "+m" (rw->lock) : : "memory");
206} 206}
207 207
208#define _raw_spin_relax(lock) cpu_relax()
209#define _raw_read_relax(lock) cpu_relax()
210#define _raw_write_relax(lock) cpu_relax()
211
208#endif /* __ASM_SPINLOCK_H */ 212#endif /* __ASM_SPINLOCK_H */
diff --git a/include/asm-ia64/spinlock.h b/include/asm-ia64/spinlock.h
index 9e83210dc312..ff857e31738a 100644
--- a/include/asm-ia64/spinlock.h
+++ b/include/asm-ia64/spinlock.h
@@ -213,4 +213,8 @@ static inline int __raw_read_trylock(raw_rwlock_t *x)
213 return (u32)ia64_cmpxchg4_acq((__u32 *)(x), new.word, old.word) == old.word; 213 return (u32)ia64_cmpxchg4_acq((__u32 *)(x), new.word, old.word) == old.word;
214} 214}
215 215
216#define _raw_spin_relax(lock) cpu_relax()
217#define _raw_read_relax(lock) cpu_relax()
218#define _raw_write_relax(lock) cpu_relax()
219
216#endif /* _ASM_IA64_SPINLOCK_H */ 220#endif /* _ASM_IA64_SPINLOCK_H */
diff --git a/include/asm-m32r/spinlock.h b/include/asm-m32r/spinlock.h
index f9f90727a4a1..f5cfba81ee10 100644
--- a/include/asm-m32r/spinlock.h
+++ b/include/asm-m32r/spinlock.h
@@ -316,4 +316,8 @@ static inline int __raw_write_trylock(raw_rwlock_t *lock)
316 return 0; 316 return 0;
317} 317}
318 318
319#define _raw_spin_relax(lock) cpu_relax()
320#define _raw_read_relax(lock) cpu_relax()
321#define _raw_write_relax(lock) cpu_relax()
322
319#endif /* _ASM_M32R_SPINLOCK_H */ 323#endif /* _ASM_M32R_SPINLOCK_H */
diff --git a/include/asm-mips/spinlock.h b/include/asm-mips/spinlock.h
index 4c1a1b53aeaf..c8d5587467bb 100644
--- a/include/asm-mips/spinlock.h
+++ b/include/asm-mips/spinlock.h
@@ -328,4 +328,8 @@ static inline int __raw_write_trylock(raw_rwlock_t *rw)
328} 328}
329 329
330 330
331#define _raw_spin_relax(lock) cpu_relax()
332#define _raw_read_relax(lock) cpu_relax()
333#define _raw_write_relax(lock) cpu_relax()
334
331#endif /* _ASM_SPINLOCK_H */ 335#endif /* _ASM_SPINLOCK_H */
diff --git a/include/asm-parisc/spinlock.h b/include/asm-parisc/spinlock.h
index a93960e232cf..e1825530365d 100644
--- a/include/asm-parisc/spinlock.h
+++ b/include/asm-parisc/spinlock.h
@@ -152,4 +152,8 @@ static __inline__ int __raw_write_can_lock(raw_rwlock_t *rw)
152 return !rw->counter; 152 return !rw->counter;
153} 153}
154 154
155#define _raw_spin_relax(lock) cpu_relax()
156#define _raw_read_relax(lock) cpu_relax()
157#define _raw_write_relax(lock) cpu_relax()
158
155#endif /* __ASM_SPINLOCK_H */ 159#endif /* __ASM_SPINLOCK_H */
diff --git a/include/asm-powerpc/spinlock.h b/include/asm-powerpc/spinlock.h
index c31e4382a775..eaccac8327f2 100644
--- a/include/asm-powerpc/spinlock.h
+++ b/include/asm-powerpc/spinlock.h
@@ -285,5 +285,9 @@ static __inline__ void __raw_write_unlock(raw_rwlock_t *rw)
285 rw->lock = 0; 285 rw->lock = 0;
286} 286}
287 287
288#define _raw_spin_relax(lock) cpu_relax()
289#define _raw_read_relax(lock) cpu_relax()
290#define _raw_write_relax(lock) cpu_relax()
291
288#endif /* __KERNEL__ */ 292#endif /* __KERNEL__ */
289#endif /* __ASM_SPINLOCK_H */ 293#endif /* __ASM_SPINLOCK_H */
diff --git a/include/asm-ppc/spinlock.h b/include/asm-ppc/spinlock.h
index 5c64b75f0295..fccaf5531e57 100644
--- a/include/asm-ppc/spinlock.h
+++ b/include/asm-ppc/spinlock.h
@@ -161,4 +161,8 @@ static __inline__ void __raw_write_unlock(raw_rwlock_t *rw)
161 rw->lock = 0; 161 rw->lock = 0;
162} 162}
163 163
164#define _raw_spin_relax(lock) cpu_relax()
165#define _raw_read_relax(lock) cpu_relax()
166#define _raw_write_relax(lock) cpu_relax()
167
164#endif /* __ASM_SPINLOCK_H */ 168#endif /* __ASM_SPINLOCK_H */
diff --git a/include/asm-s390/spinlock.h b/include/asm-s390/spinlock.h
index ce3edf6d63b3..5f00feaf1be6 100644
--- a/include/asm-s390/spinlock.h
+++ b/include/asm-s390/spinlock.h
@@ -154,4 +154,8 @@ static inline int __raw_write_trylock(raw_rwlock_t *rw)
154 return _raw_write_trylock_retry(rw); 154 return _raw_write_trylock_retry(rw);
155} 155}
156 156
157#define _raw_spin_relax(lock) cpu_relax()
158#define _raw_read_relax(lock) cpu_relax()
159#define _raw_write_relax(lock) cpu_relax()
160
157#endif /* __ASM_SPINLOCK_H */ 161#endif /* __ASM_SPINLOCK_H */
diff --git a/include/asm-sh/spinlock.h b/include/asm-sh/spinlock.h
index 846322d4c35d..54458fd24981 100644
--- a/include/asm-sh/spinlock.h
+++ b/include/asm-sh/spinlock.h
@@ -100,4 +100,8 @@ static inline int __raw_write_trylock(raw_rwlock_t *rw)
100 return 0; 100 return 0;
101} 101}
102 102
103#define _raw_spin_relax(lock) cpu_relax()
104#define _raw_read_relax(lock) cpu_relax()
105#define _raw_write_relax(lock) cpu_relax()
106
103#endif /* __ASM_SH_SPINLOCK_H */ 107#endif /* __ASM_SH_SPINLOCK_H */
diff --git a/include/asm-sparc/spinlock.h b/include/asm-sparc/spinlock.h
index 1c75474ba1df..557d08959d2f 100644
--- a/include/asm-sparc/spinlock.h
+++ b/include/asm-sparc/spinlock.h
@@ -154,6 +154,10 @@ static inline int __raw_write_trylock(raw_rwlock_t *rw)
154#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock) 154#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
155#define __raw_read_trylock(lock) generic__raw_read_trylock(lock) 155#define __raw_read_trylock(lock) generic__raw_read_trylock(lock)
156 156
157#define _raw_spin_relax(lock) cpu_relax()
158#define _raw_read_relax(lock) cpu_relax()
159#define _raw_write_relax(lock) cpu_relax()
160
157#define __raw_read_can_lock(rw) (!((rw)->lock & 0xff)) 161#define __raw_read_can_lock(rw) (!((rw)->lock & 0xff))
158#define __raw_write_can_lock(rw) (!(rw)->lock) 162#define __raw_write_can_lock(rw) (!(rw)->lock)
159 163
diff --git a/include/asm-sparc64/spinlock.h b/include/asm-sparc64/spinlock.h
index bd5ffc76bc7e..0006fe9f8c7a 100644
--- a/include/asm-sparc64/spinlock.h
+++ b/include/asm-sparc64/spinlock.h
@@ -241,6 +241,10 @@ static int inline __write_trylock(raw_rwlock_t *lock)
241#define __raw_read_can_lock(rw) (!((rw)->lock & 0x80000000UL)) 241#define __raw_read_can_lock(rw) (!((rw)->lock & 0x80000000UL))
242#define __raw_write_can_lock(rw) (!(rw)->lock) 242#define __raw_write_can_lock(rw) (!(rw)->lock)
243 243
244#define _raw_spin_relax(lock) cpu_relax()
245#define _raw_read_relax(lock) cpu_relax()
246#define _raw_write_relax(lock) cpu_relax()
247
244#endif /* !(__ASSEMBLY__) */ 248#endif /* !(__ASSEMBLY__) */
245 249
246#endif /* !(__SPARC64_SPINLOCK_H) */ 250#endif /* !(__SPARC64_SPINLOCK_H) */
diff --git a/include/asm-x86_64/spinlock.h b/include/asm-x86_64/spinlock.h
index 3daf5b005905..05ef097ba55b 100644
--- a/include/asm-x86_64/spinlock.h
+++ b/include/asm-x86_64/spinlock.h
@@ -133,4 +133,8 @@ static inline void __raw_write_unlock(raw_rwlock_t *rw)
133 : "=m" (rw->lock) : : "memory"); 133 : "=m" (rw->lock) : : "memory");
134} 134}
135 135
136#define _raw_spin_relax(lock) cpu_relax()
137#define _raw_read_relax(lock) cpu_relax()
138#define _raw_write_relax(lock) cpu_relax()
139
136#endif /* __ASM_SPINLOCK_H */ 140#endif /* __ASM_SPINLOCK_H */