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authorSiddhesh Poyarekar <siddhesh@redhat.com>2012-11-05 21:12:10 +0530
committerSiddhesh Poyarekar <siddhesh@redhat.com>2012-11-05 21:12:52 +0530
commit8f861542dd0603bef99e126e509ece89514c1eeb (patch)
tree083f3bd20edfa09a2341e0340013c0781b4696ad /nptl/sysdeps
parent155ee340b875834693fbd1b7401af7fe88ace04d (diff)
downloadglibc-8f861542dd0603bef99e126e509ece89514c1eeb.tar.gz
[S390,PPC] Implement FUTEX_WAIT_BITSET for timedwait functions
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.
Diffstat (limited to 'nptl/sysdeps')
-rw-r--r--nptl/sysdeps/unix/sysv/linux/lowlevelrobustlock.c16
-rw-r--r--nptl/sysdeps/unix/sysv/linux/powerpc/lowlevellock.h13
-rw-r--r--nptl/sysdeps/unix/sysv/linux/s390/lowlevellock.h20
3 files changed, 48 insertions, 1 deletions
diff --git a/nptl/sysdeps/unix/sysv/linux/lowlevelrobustlock.c b/nptl/sysdeps/unix/sysv/linux/lowlevelrobustlock.c
index 7b4e84343c..9a9e67303b 100644
--- a/nptl/sysdeps/unix/sysv/linux/lowlevelrobustlock.c
+++ b/nptl/sysdeps/unix/sysv/linux/lowlevelrobustlock.c
@@ -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:
;
diff --git a/nptl/sysdeps/unix/sysv/linux/powerpc/lowlevellock.h b/nptl/sysdeps/unix/sysv/linux/powerpc/lowlevellock.h
index 406c290d71..17e63c6901 100644
--- a/nptl/sysdeps/unix/sysv/linux/powerpc/lowlevellock.h
+++ b/nptl/sysdeps/unix/sysv/linux/powerpc/lowlevellock.h
@@ -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); \
diff --git a/nptl/sysdeps/unix/sysv/linux/s390/lowlevellock.h b/nptl/sysdeps/unix/sysv/linux/s390/lowlevellock.h
index 97092823df..0b7110f11b 100644
--- a/nptl/sysdeps/unix/sysv/linux/s390/lowlevellock.h
+++ b/nptl/sysdeps/unix/sysv/linux/s390/lowlevellock.h
@@ -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) \
({ \