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[S390,PPC] Implement FUTEX_WAIT_BITSET for timedwait functions

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Since the FUTEX_WAIT operation takes a relative timeout, the
pthread_cond_timedwait and other timed function implementations have
to get a relative timeout from the absolute timeout parameter it gets
before it makes the futex syscall.  This value is then converted back
into an absolute timeout within the kernel.  This is a waste and has
hence been improved upon by a FUTEX_WAIT_BITSET operation (OR'd with
FUTEX_CLOCK_REALTIME to make the kernel use the realtime clock instead
of the default monotonic clock).  This was implemented only in the x86
and sh assembly code and not in the C code.  This patch implements
support for FUTEX_WAIT_BITSET whenever available (since linux-2.6.29)
for s390 and powerpc.
This commit is contained in:
Siddhesh Poyarekar 2012-11-05 21:12:10 +05:30
parent 155ee340b8
commit 8f861542dd
7 changed files with 124 additions and 6 deletions
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17
nptl/ChangeLog
View file

@ -1,3 +1,20 @@
2012-11-05 Siddhesh Poyarekar <siddhesh@redhat.com>
* pthread_cond_timedwait.c (__pthread_cond_timedwait): Time out
if absolute timeout is negative.
[__ASSUME_FUTEX_CLOCK_REALTIME &&
lll_futex_timed_wait_bitset]: Use lll_futex_timed_wait_bitset.
* pthread_rwlock_timedrdlock.c (pthread_rwlock_timedrdlock):
Likewise.
* pthread_rwlock_timedwrlock.c (pthread_rwlock_timedwrlock):
Likewise.
* sysdeps/unix/sysv/linux/lowlevelrobustlock.c
(__lll_robust_timedlock_wait): Likewise.
* sysdeps/unix/sysv/linux/powerpc/lowlevellock.h
(lll_futex_timed_wait_bitset): New macro.
* sysdeps/unix/sysv/linux/s390/lowlevellock.h
(lll_futex_timed_wait_bitset): Likewise.
2012-11-03 David S. Miller <davem@davemloft.net>
* sysdeps/unix/sysv/linux/sparc/lowlevellock.h (BUSY_WAIT_NOP):

22
nptl/pthread_cond_timedwait.c
View file

@ -80,6 +80,11 @@ __pthread_cond_timedwait (cond, mutex, abstime)
++cond->__data.__futex;
cond->__data.__nwaiters += 1 << COND_NWAITERS_SHIFT;
/* Work around the fact that the kernel rejects negative timeout values
despite them being valid. */
if (__builtin_expect (abstime->tv_sec < 0, 0))
goto timeout;
/* Remember the mutex we are using here. If there is already a
different address store this is a bad user bug. Do not store
anything for pshared condvars. */
@ -104,9 +109,11 @@ __pthread_cond_timedwait (cond, mutex, abstime)
while (1)
{
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
|| !defined lll_futex_timed_wait_bitset)
struct timespec rt;
{
#ifdef __NR_clock_gettime
# ifdef __NR_clock_gettime
INTERNAL_SYSCALL_DECL (err);
int ret;
ret = INTERNAL_VSYSCALL (clock_gettime, err, 2,
@ -116,7 +123,7 @@ __pthread_cond_timedwait (cond, mutex, abstime)
/* Convert the absolute timeout value to a relative timeout. */
rt.tv_sec = abstime->tv_sec - rt.tv_sec;
rt.tv_nsec = abstime->tv_nsec - rt.tv_nsec;
#else
# else
/* Get the current time. So far we support only one clock. */
struct timeval tv;
(void) gettimeofday (&tv, NULL);
@ -124,7 +131,7 @@ __pthread_cond_timedwait (cond, mutex, abstime)
/* Convert the absolute timeout value to a relative timeout. */
rt.tv_sec = abstime->tv_sec - tv.tv_sec;
rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
#endif
# endif
}
if (rt.tv_nsec < 0)
{
@ -139,6 +146,7 @@ __pthread_cond_timedwait (cond, mutex, abstime)
goto timeout;
}
#endif
unsigned int futex_val = cond->__data.__futex;
@ -148,9 +156,17 @@ __pthread_cond_timedwait (cond, mutex, abstime)
/* Enable asynchronous cancellation. Required by the standard. */
cbuffer.oldtype = __pthread_enable_asynccancel ();
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
|| !defined lll_futex_timed_wait_bitset)
/* Wait until woken by signal or broadcast. */
err = lll_futex_timed_wait (&cond->__data.__futex,
futex_val, &rt, pshared);
#else
unsigned int clockbit = (cond->__data.__nwaiters & 1
? 0 : FUTEX_CLOCK_REALTIME);
err = lll_futex_timed_wait_bitset (&cond->__data.__futex, futex_val,
abstime, clockbit, pshared);
#endif
/* Disable asynchronous cancellation. */
__pthread_disable_asynccancel (cbuffer.oldtype);

21
nptl/pthread_rwlock_timedrdlock.c
View file

@ -1,4 +1,4 @@
/* Copyright (C) 2003,2004,2007,2011 Free Software Foundation, Inc.
/* Copyright (C) 2003-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
@ -76,6 +76,16 @@ pthread_rwlock_timedrdlock (rwlock, abstime)
break;
}
/* Work around the fact that the kernel rejects negative timeout values
despite them being valid. */
if (__builtin_expect (abstime->tv_sec < 0, 0))
{
result = ETIMEDOUT;
break;
}
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
|| !defined lll_futex_timed_wait_bitset)
/* Get the current time. So far we support only one clock. */
struct timeval tv;
(void) gettimeofday (&tv, NULL);
@ -96,6 +106,7 @@ pthread_rwlock_timedrdlock (rwlock, abstime)
result = ETIMEDOUT;
break;
}
#endif
/* Remember that we are a reader. */
if (++rwlock->__data.__nr_readers_queued == 0)
@ -112,8 +123,16 @@ pthread_rwlock_timedrdlock (rwlock, abstime)
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
/* Wait for the writer to finish. */
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
|| !defined lll_futex_timed_wait_bitset)
err = lll_futex_timed_wait (&rwlock->__data.__readers_wakeup,
waitval, &rt, rwlock->__data.__shared);
#else
err = lll_futex_timed_wait_bitset (&rwlock->__data.__readers_wakeup,
waitval, abstime,
FUTEX_CLOCK_REALTIME,
rwlock->__data.__shared);
#endif
/* Get the lock. */
lll_lock (rwlock->__data.__lock, rwlock->__data.__shared);

21
nptl/pthread_rwlock_timedwrlock.c
View file

@ -1,4 +1,4 @@
/* Copyright (C) 2003,2004,2007,2011 Free Software Foundation, Inc.
/* Copyright (C) 2003-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
@ -67,6 +67,16 @@ pthread_rwlock_timedwrlock (rwlock, abstime)
break;
}
/* Work around the fact that the kernel rejects negative timeout values
despite them being valid. */
if (__builtin_expect (abstime->tv_sec < 0, 0))
{
result = ETIMEDOUT;
break;
}
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
|| !defined lll_futex_timed_wait_bitset)
/* Get the current time. So far we support only one clock. */
struct timeval tv;
(void) gettimeofday (&tv, NULL);
@ -86,6 +96,7 @@ pthread_rwlock_timedwrlock (rwlock, abstime)
result = ETIMEDOUT;
break;
}
#endif
/* Remember that we are a writer. */
if (++rwlock->__data.__nr_writers_queued == 0)
@ -102,8 +113,16 @@ pthread_rwlock_timedwrlock (rwlock, abstime)
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
/* Wait for the writer or reader(s) to finish. */
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
|| !defined lll_futex_timed_wait_bitset)
err = lll_futex_timed_wait (&rwlock->__data.__writer_wakeup,
waitval, &rt, rwlock->__data.__shared);
#else
err = lll_futex_timed_wait_bitset (&rwlock->__data.__writer_wakeup,
waitval, abstime,
FUTEX_CLOCK_REALTIME,
rwlock->__data.__shared);
#endif
/* Get the lock. */
lll_lock (rwlock->__data.__lock, rwlock->__data.__shared);

16
nptl/sysdeps/unix/sysv/linux/lowlevelrobustlock.c
View file

@ -1,4 +1,4 @@
/* Copyright (C) 2006, 2007 Free Software Foundation, Inc.
/* Copyright (C) 2006-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Jakub Jelinek <jakub@redhat.com>, 2006.
@ -70,8 +70,15 @@ __lll_robust_timedlock_wait (int *futex, const struct timespec *abstime,
if (oldval == 0)
goto try;
/* Work around the fact that the kernel rejects negative timeout values
despite them being valid. */
if (__builtin_expect (abstime->tv_sec < 0, 0))
return ETIMEDOUT;
do
{
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
|| !defined lll_futex_timed_wait_bitset)
struct timeval tv;
struct timespec rt;
@ -90,6 +97,7 @@ __lll_robust_timedlock_wait (int *futex, const struct timespec *abstime,
/* Already timed out? */
if (rt.tv_sec < 0)
return ETIMEDOUT;
#endif
/* Wait. */
if (__builtin_expect (oldval & FUTEX_OWNER_DIED, 0))
@ -100,7 +108,13 @@ __lll_robust_timedlock_wait (int *futex, const struct timespec *abstime,
&& atomic_compare_and_exchange_bool_acq (futex, newval, oldval))
continue;
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
|| !defined lll_futex_timed_wait_bitset)
lll_futex_timed_wait (futex, newval, &rt, private);
#else
lll_futex_timed_wait_bitset (futex, newval, abstime,
FUTEX_CLOCK_REALTIME, private);
#endif
try:
;

13
nptl/sysdeps/unix/sysv/linux/powerpc/lowlevellock.h
View file

@ -88,6 +88,19 @@
INTERNAL_SYSCALL_ERROR_P (__ret, __err) ? -__ret : __ret; \
})
#define lll_futex_timed_wait_bitset(futexp, val, timespec, clockbit, private) \
({ \
INTERNAL_SYSCALL_DECL (__err); \
long int __ret; \
int __op = FUTEX_WAIT_BITSET | clockbit; \
\
__ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp), \
__lll_private_flag (__op, private), \
(val), (timespec), NULL /* Unused. */, \
FUTEX_BITSET_MATCH_ANY); \
INTERNAL_SYSCALL_ERROR_P (__ret, __err) ? -__ret : __ret; \
})
#define lll_futex_wake(futexp, nr, private) \
({ \
INTERNAL_SYSCALL_DECL (__err); \

20
nptl/sysdeps/unix/sysv/linux/s390/lowlevellock.h
View file

@ -93,6 +93,26 @@
__result; \
})
#define lll_futex_timed_wait_bitset(futexp, val, timespec, clockbit, private) \
({ \
register unsigned long int __r2 asm ("2") = (unsigned long int) (futexp); \
register unsigned long int __r3 asm ("3") \
= __lll_private_flag ((FUTEX_WAIT_BITSET | clockbit), private); \
register unsigned long int __r4 asm ("4") = (long int) (val); \
register unsigned long int __r5 asm ("5") = (long int) (timespec); \
register unsigned long int __r6 asm ("6") = (unsigned long int) (NULL); \
register unsigned long int __r7 asm ("7") \
= (unsigned int) (FUTEX_BITSET_MATCH_ANY); \
register unsigned long __result asm ("2"); \
\
__asm __volatile ("svc %b1" \
: "=d" (__result) \
: "i" (SYS_futex), "0" (__r2), "d" (__r3), \
"d" (__r4), "d" (__r5), "d" (__r6), "d" (__r7) \
: "cc", "memory" ); \
__result; \
})
#define lll_futex_wake(futex, nr, private) \
({ \