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[PATCH] powerpc: Fix usage of elision transient failure adapt param
- From: "Paul E. Murphy" <murphyp at linux dot vnet dot ibm dot com>
- To: "libc-alpha at sourceware dot org" <libc-alpha at sourceware dot org>
- Cc: Steve Munroe <sjmunroe at us dot ibm dot com>, Tulio Magno Quites Machado Filho <tuliom at linux dot vnet dot ibm dot com>
- Date: Thu, 20 Aug 2015 14:08:41 -0500
- Subject: [PATCH] powerpc: Fix usage of elision transient failure adapt param
- Authentication-results: sourceware.org; auth=none
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.
2015-08-20 Paul E. Murphy <murphyp@linux.vnet.ibm.com>
* 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
---
sysdeps/powerpc/nptl/elide.h | 10 +++++-----
sysdeps/unix/sysv/linux/powerpc/elision-lock.c | 15 ++++++---------
2 files changed, 11 insertions(+), 14 deletions(-)
diff --git a/sysdeps/powerpc/nptl/elide.h b/sysdeps/powerpc/nptl/elide.h
index 389f5a5..38e1565 100644
--- a/sysdeps/powerpc/nptl/elide.h
+++ b/sysdeps/powerpc/nptl/elide.h
@@ -55,14 +55,14 @@ __elide_lock (uint8_t *adapt_count, int is_lock_free)
*adapt_count = __elision_aconf.skip_lock_internal_abort;
break;
}
- /* 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
- && __elision_aconf.try_tbegin > 0)
- *adapt_count = __elision_aconf.skip_lock_out_of_tbegin_retries;
}
}
+ /* Fall back to locks for a bit if retries have been exceeded */
+ if (__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 false;
}
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);
}
--
1.7.1