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powerpc: Fix usage of elision transient failure adapt param

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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.
This commit is contained in:
Paul Murphy 2015-08-27 09:48:04 -05:00 committed by Tulio Magno Quites Machado Filho
parent 76c5ae0028
commit 72f1463df8
4 changed files with 19 additions and 13 deletions
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9
ChangeLog
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@ -1,3 +1,12 @@
2015-10-27 Paul E. Murphy <murphyp@linux.vnet.ibm.com>
[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.
2015-10-27 Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>
* elf/dl-support.c (_dl_aux_init): Added AT_PLATFORM to the case

2
NEWS
View File

@ -21,7 +21,7 @@ Version 2.23
18970, 18977, 18980, 18981, 18982, 18985, 19003, 19007, 19012, 19016,
19018, 19032, 19046, 19049, 19050, 19059, 19071, 19074, 19076, 19077,
19078, 19079, 19085, 19086, 19088, 19094, 19095, 19124, 19125, 19129,
19134, 19137, 19156.
19134, 19137, 19156, 19174.
* There is now a --disable-timezone-tools configure option for disabling the
building and installing of the timezone related utilities (zic, zdump, and

6
sysdeps/powerpc/nptl/elide.h
View File

@ -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; \

15
sysdeps/unix/sysv/linux/powerpc/elision-lock.c
View File

@ -50,8 +50,7 @@ __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))
{
@ -65,21 +64,19 @@ __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);
}