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GNU C Library master sources branch gentoo/2.22 updated. glibc-2.22-34-g23f12d0
- From: vapier at sourceware dot org
- To: glibc-cvs at sourceware dot org
- Date: 16 Feb 2016 19:13:11 -0000
- Subject: GNU C Library master sources branch gentoo/2.22 updated. glibc-2.22-34-g23f12d0
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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=23f12d0a815e55ab60a0e6d973fc3f4730ca6980
commit 23f12d0a815e55ab60a0e6d973fc3f4730ca6980
Author: Paul Murphy <murphyp@linux.vnet.ibm.com>
Date: Thu Aug 27 09:48:04 2015 -0500
powerpc: Fix usage of elision transient failure adapt param
The skip_lock_out_of_tbegin_retries adaptive parameter was
not being used correctly, nor as described. This prevents
a fallback for all users of the lock if a transient abort
occurs within the accepted number of retries.
[BZ #19174]
* sysdeps/powerpc/nptl/elide.h (__elide_lock): Fix usage of
.skip_lock_out_of_tbegin_retries.
* sysdeps/unix/sysv/linux/powerpc/elision-lock.c
(__lll_lock_elision): Likewise, and respect a value of
try_tbegin <= 0.
(cherry picked from commit 72f1463df85a522bfd1568e47bd81371522ee358)
Conflicts:
NEWS
(cherry picked from commit cd51b1424477652cccdb83e7a95644d198fd4513)
diff --git a/sysdeps/powerpc/nptl/elide.h b/sysdeps/powerpc/nptl/elide.h
index 12171f4..2e1e443 100644
--- a/sysdeps/powerpc/nptl/elide.h
+++ b/sysdeps/powerpc/nptl/elide.h
@@ -27,7 +27,7 @@
configurations. Returns true if the system should retry again or false
otherwise. */
static inline bool
-__get_new_count (uint8_t *adapt_count)
+__get_new_count (uint8_t *adapt_count, int attempt)
{
/* A persistent failure indicates that a retry will probably
result in another failure. Use normal locking now and
@@ -40,7 +40,7 @@ __get_new_count (uint8_t *adapt_count)
}
/* Same logic as above, but for a number of temporary failures in a
a row. */
- else if (__elision_aconf.skip_lock_out_of_tbegin_retries > 0
+ else if (attempt <= 1 && __elision_aconf.skip_lock_out_of_tbegin_retries > 0
&& __elision_aconf.try_tbegin > 0)
*adapt_count = __elision_aconf.skip_lock_out_of_tbegin_retries;
return true;
@@ -78,7 +78,7 @@ __get_new_count (uint8_t *adapt_count)
__builtin_tabort (_ABORT_LOCK_BUSY); \
} \
else \
- if (!__get_new_count(&adapt_count)) \
+ if (!__get_new_count (&adapt_count,i)) \
break; \
} \
ret; \
diff --git a/sysdeps/unix/sysv/linux/powerpc/elision-lock.c b/sysdeps/unix/sysv/linux/powerpc/elision-lock.c
index 7f9bcc2..c6731ca 100644
--- a/sysdeps/unix/sysv/linux/powerpc/elision-lock.c
+++ b/sysdeps/unix/sysv/linux/powerpc/elision-lock.c
@@ -72,8 +72,7 @@ __lll_lock_elision (int *lock, short *adapt_count, EXTRAARG int pshared)
goto use_lock;
}
- int try_begin = aconf.try_tbegin;
- while (1)
+ for (int i = aconf.try_tbegin; i > 0; i--)
{
if (__builtin_tbegin (0))
{
@@ -87,21 +86,19 @@ __lll_lock_elision (int *lock, short *adapt_count, EXTRAARG int pshared)
/* A persistent failure indicates that a retry will probably
result in another failure. Use normal locking now and
for the next couple of calls. */
- if (try_begin-- <= 0
- || _TEXASRU_FAILURE_PERSISTENT (__builtin_get_texasru ()))
+ if (_TEXASRU_FAILURE_PERSISTENT (__builtin_get_texasru ()))
{
if (aconf.skip_lock_internal_abort > 0)
*adapt_count = aconf.skip_lock_internal_abort;
goto use_lock;
}
- /* Same logic as above, but for for a number of temporary failures
- in a row. */
- else if (aconf.skip_lock_out_of_tbegin_retries > 0
- && aconf.try_tbegin > 0)
- *adapt_count = aconf.skip_lock_out_of_tbegin_retries;
}
}
+ /* Fall back to locks for a bit if retries have been exhausted */
+ if (aconf.try_tbegin > 0 && aconf.skip_lock_out_of_tbegin_retries > 0)
+ *adapt_count = aconf.skip_lock_out_of_tbegin_retries;
+
use_lock:
return LLL_LOCK ((*lock), pshared);
}
-----------------------------------------------------------------------
Summary of changes:
sysdeps/powerpc/nptl/elide.h | 6 +++---
sysdeps/unix/sysv/linux/powerpc/elision-lock.c | 15 ++++++---------
2 files changed, 9 insertions(+), 12 deletions(-)
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