* [Bug nptl/13701] pthread_rwlock_rdlock & realtime scheduling writer lock precedence
2012-02-16 17:05 [Bug nptl/13701] New: pthread_rwlock_rdlock & realtime scheduling writer lock precedence chrubis at suse dot cz
@ 2012-12-19 10:47 ` schwab@linux-m68k.org
2013-08-28 6:27 ` vapier at gentoo dot org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: schwab@linux-m68k.org @ 2012-12-19 10:47 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=13701
Andreas Schwab <schwab@linux-m68k.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|drepper.fsp at gmail dot |unassigned at sourceware
|com |dot org
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^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug nptl/13701] pthread_rwlock_rdlock & realtime scheduling writer lock precedence
2012-02-16 17:05 [Bug nptl/13701] New: pthread_rwlock_rdlock & realtime scheduling writer lock precedence chrubis at suse dot cz
2012-12-19 10:47 ` [Bug nptl/13701] " schwab@linux-m68k.org
@ 2013-08-28 6:27 ` vapier at gentoo dot org
2014-04-15 1:18 ` wangxg.fnst at cn dot fujitsu.com
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: vapier at gentoo dot org @ 2013-08-28 6:27 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=13701
Mike Frysinger <vapier at gentoo dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
URL| |http://austingroupbugs.net/
| |view.php?id=722
CC| |vapier at gentoo dot org
See Also| |https://bugzilla.novell.com
| |/show_bug.cgi?id=66013,
| |http://austingroupbugs.net/
| |view.php?id=722
--- Comment #1 from Mike Frysinger <vapier at gentoo dot org> ---
discussion has moved to the austin group tracker now
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^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug nptl/13701] pthread_rwlock_rdlock & realtime scheduling writer lock precedence
2012-02-16 17:05 [Bug nptl/13701] New: pthread_rwlock_rdlock & realtime scheduling writer lock precedence chrubis at suse dot cz
2012-12-19 10:47 ` [Bug nptl/13701] " schwab@linux-m68k.org
2013-08-28 6:27 ` vapier at gentoo dot org
@ 2014-04-15 1:18 ` wangxg.fnst at cn dot fujitsu.com
2014-06-26 15:22 ` fweimer at redhat dot com
2015-04-28 20:02 ` triegel at redhat dot com
4 siblings, 0 replies; 6+ messages in thread
From: wangxg.fnst at cn dot fujitsu.com @ 2014-04-15 1:18 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=13701
Xiaoguang Wang <wangxg.fnst at cn dot fujitsu.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |wangxg.fnst at cn dot fujitsu.com
--- Comment #2 from Xiaoguang Wang <wangxg.fnst at cn dot fujitsu.com> ---
According to austin group's discussion results, it seems that write locks
should be implemented to take precedence before the read locks.
Whether is this considered as a glibc bug or should be fixed? Thanks.
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^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug nptl/13701] pthread_rwlock_rdlock & realtime scheduling writer lock precedence
2012-02-16 17:05 [Bug nptl/13701] New: pthread_rwlock_rdlock & realtime scheduling writer lock precedence chrubis at suse dot cz
` (2 preceding siblings ...)
2014-04-15 1:18 ` wangxg.fnst at cn dot fujitsu.com
@ 2014-06-26 15:22 ` fweimer at redhat dot com
2015-04-28 20:02 ` triegel at redhat dot com
4 siblings, 0 replies; 6+ messages in thread
From: fweimer at redhat dot com @ 2014-06-26 15:22 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=13701
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Flags| |security-
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^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug nptl/13701] pthread_rwlock_rdlock & realtime scheduling writer lock precedence
2012-02-16 17:05 [Bug nptl/13701] New: pthread_rwlock_rdlock & realtime scheduling writer lock precedence chrubis at suse dot cz
` (3 preceding siblings ...)
2014-06-26 15:22 ` fweimer at redhat dot com
@ 2015-04-28 20:02 ` triegel at redhat dot com
4 siblings, 0 replies; 6+ messages in thread
From: triegel at redhat dot com @ 2015-04-28 20:02 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=13701
Torvald Riegel <triegel at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P2 |P3
CC| |triegel at redhat dot com
Severity|normal |enhancement
--- Comment #3 from Torvald Riegel <triegel at redhat dot com> ---
Precisely, if Thread Execution Scheduling is supported (and glibc claims it
is), and if the threads use SCHED_FIFO / SCHED_RR / SCHED_SPORADIC,
pthread_rwlock_rdlock() must prefer blocked writers if and only if their
priority is higher or equal to that of the reader; otherwise, the reader is
preferred:
http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_rwlock_rdlock.html
The current implementation does not guarantee that; instead, it prefers readers
if other readers have already acquired the lock, or neither readers nor writers
have acquired the lock. The former seems to be, intuitively, the right
behavior given that recursive rdlock acquisitions are allowed also.
Implementing the special requirements for Thread Execution Scheduling seems
difficult, especially in an efficient way, and given the futex facilities we
have today and the role userspace has when using them (e.g., the rwlock
implementation would need to track the maximum priority of all blocked writers,
yet we'd need to still support process-shared rwlocks). Therefore, unless
there is strong demand for this feature, I don't think it's worthwhile to spend
significant time on this.
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^ permalink raw reply [flat|nested] 6+ messages in thread