[PATCH 26/29] x86, tsx: Add adaptation support to rw spinlocks

Andi Kleen
2013-03-23T01:30:16Z

Add elision adaptation state to the rwlocks and use the generic
adaptation wrapper. This unfortunately increases the size of the rwlock:
6 bytes for NR_CPUS>=2048, otherwise by 2 bytes.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
arch/x86/include/asm/rwlock.h | 30 +++++++++++++++++++++---------
arch/x86/kernel/rtm-locks.c | 22 +++++++++++++++++-----
2 files changed, 38 insertions(+), 14 deletions(-)

diff --git a/arch/x86/include/asm/rwlock.h b/arch/x86/include/asm/rwlock.h
index a5370a0..a3929cc 100644
--- a/arch/x86/include/asm/rwlock.h
+++ b/arch/x86/include/asm/rwlock.h
@@ -6,9 +6,15 @@
#if CONFIG_NR_CPUS <= 2048

#ifndef __ASSEMBLY__
-typedef union {
- s32 lock;
- s32 write;
+typedef struct {
+ union {
+ s32 lock;
+ s32 write;
+ };
+#ifdef CONFIG_RTM_LOCKS
+ short elision_adapt;
+ /* 2 bytes padding */
+#endif
} arch_rwlock_t;
#endif

@@ -24,12 +30,18 @@ typedef union {
#include <linux/const.h>

#ifndef __ASSEMBLY__
-typedef union {
- s64 lock;
- struct {
- u32 read;
- s32 write;
+typedef struct {
+ union {
+ s64 lock;
+ struct {
+ u32 read;
+ s32 write;
+ };
};
+#ifdef CONFIG_RTM_LOCKS
+ short elision_adapt;
+ /* 6 bytes padding for now */
+#endif
} arch_rwlock_t;
#endif

@@ -42,7 +54,7 @@ typedef union {

#endif /* CONFIG_NR_CPUS */

-#define __ARCH_RW_LOCK_UNLOCKED { RW_LOCK_BIAS }
+#define __ARCH_RW_LOCK_UNLOCKED { { RW_LOCK_BIAS } }

/* Actual code is in asm/spinlock.h or in arch/x86/lib/rwlock.S */

diff --git a/arch/x86/kernel/rtm-locks.c b/arch/x86/kernel/rtm-locks.c
index 1651049..bc3275a 100644
--- a/arch/x86/kernel/rtm-locks.c
+++ b/arch/x86/kernel/rtm-locks.c
@@ -155,8 +155,16 @@ static int rtm_spin_is_locked(struct arch_spinlock *lock)
* This uses direct calls with static patching, not pvops.
*/

-__read_mostly bool rwlock_elision = true;
-module_param(rwlock_elision, bool, 0644);
+static struct static_key rwlock_elision = STATIC_KEY_INIT_FALSE;
+module_param(rwlock_elision, static_key, 0644);
+
+static __read_mostly struct elision_config readlock_elision_config =
+ DEFAULT_ELISION_CONFIG;
+TUNE_ELISION_CONFIG(readlock, readlock_elision_config);
+
+static __read_mostly struct elision_config writelock_elision_config =
+ DEFAULT_ELISION_CONFIG;
+TUNE_ELISION_CONFIG(writelock, writelock_elision_config);

void rtm_read_lock(arch_rwlock_t *rw)
{
@@ -167,7 +175,8 @@ void rtm_read_lock(arch_rwlock_t *rw)
* would abort anyways.
*/

- if (!elide_lock(rwlock_elision, !arch_rwlock_is_locked(rw)))
+ if (!elide_lock_adapt(rwlock_elision, !arch_rwlock_is_locked(rw),
+ &rw->elision_adapt, &readlock_elision_config))
arch_do_read_lock(rw);
}
EXPORT_SYMBOL(rtm_read_lock);
@@ -210,7 +219,8 @@ EXPORT_SYMBOL(rtm_read_unlock_irqrestore);

int rtm_read_trylock(arch_rwlock_t *rw)
{
- if (elide_lock(rwlock_elision, !arch_rwlock_is_locked(rw)))
+ if (elide_lock_adapt(rwlock_elision, !arch_rwlock_is_locked(rw),
+ &rw->elision_adapt, &readlock_elision_config))
return 1;
return arch_do_read_trylock(rw);
}
@@ -218,7 +228,8 @@ EXPORT_SYMBOL(rtm_read_trylock);

void rtm_write_lock(arch_rwlock_t *rw)
{
- if (!elide_lock(rwlock_elision, !arch_write_can_lock(rw)))
+ if (!elide_lock_adapt(rwlock_elision, !arch_write_can_lock(rw),
+ &rw->elision_adapt, &writelock_elision_config))
arch_do_write_lock(rw);
}
EXPORT_SYMBOL(rtm_write_lock);
@@ -451,6 +462,7 @@ void init_rtm_spinlocks(void)
pv_irq_ops.restore_fl = PV_CALLEE_SAVE(rtm_restore_fl);
pv_init_ops.patch = rtm_patch;

+ static_key_slow_inc(&rwlock_elision);
static_key_slow_inc(&mutex_elision);
}

--
1.7.7.6