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futex_requeue_pi optimization

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This patch provides the futex_requeue_pi functionality, which allows some
threads waiting on a normal futex to be requeued on the wait-queue of a
PI-futex.

This provides an optimization, already used for (normal) futexes, to be used
with the PI-futexes.

This optimization is currently used by the glibc in pthread_broadcast, when
using "normal" mutexes.  With futex_requeue_pi, it can be used with
PRIO_INHERIT mutexes too.

Signed-off-by: Pierre Peiffer <pierre.peiffer@bull.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Pierre Peiffer 2007-05-09 02:35:02 -07:00 • committed by Linus Torvalds
parent c19384b5b2
commit d0aa7a70bf
5 changed files with 540 additions and 88 deletions
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9
include/linux/futex.h
View file

@ -17,6 +17,7 @@ union ktime;
#define FUTEX_LOCK_PI 6
#define FUTEX_UNLOCK_PI 7
#define FUTEX_TRYLOCK_PI 8
#define FUTEX_CMP_REQUEUE_PI 9
/*
* Support for robust futexes: the kernel cleans up held futexes at
@ -84,10 +85,15 @@ struct robust_list_head {
*/
#define FUTEX_OWNER_DIED 0x40000000
/*
* Some processes have been requeued on this PI-futex
*/
#define FUTEX_WAITER_REQUEUED 0x20000000
/*
* The rest of the robust-futex field is for the TID:
*/
#define FUTEX_TID_MASK 0x3fffffff
#define FUTEX_TID_MASK 0x0fffffff
/*
* This limit protects against a deliberately circular list.
@ -111,6 +117,7 @@ handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);
* We set bit 0 to indicate if it's an inode-based key.
*/
union futex_key {
u32 __user *uaddr;
struct {
unsigned long pgoff;
struct inode *inode;