| Bug #54726 | Inconsistent reporting between mutex and RW lock spin rounds | ||
|---|---|---|---|
| Submitted: | 23 Jun 2010 9:28 | Modified: | 1 Dec 2010 20:01 |
| Reporter: | Mark Leith | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Server: InnoDB storage engine | Severity: | S3 (Non-critical) |
| Version: | 5.5 | OS: | Any |
| Assigned to: | Mark Leith | CPU Architecture: | Any |
[30 Jun 2010 9:13]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/112530 3129 Mark Leith 2010-06-30 Bug#54726 - Inconsistent reporting between mutex and RW lock spin rounds - Add round counts to the output for RW s/x locks
[30 Jun 2010 9:21]
Mark Leith
Pushed to mysql-trunk-innodb:
3129 Mark Leith 2010-06-30
Bug#54726 - Inconsistent reporting between mutex and RW lock spin rounds
- Add round counts to the output for RW s/x locks
modified:
storage/innobase/sync/sync0sync.c
[4 Aug 2010 7:49]
Bugs System
Pushed into mysql-trunk 5.5.6-m3 (revid:alik@sun.com-20100731131027-1n61gseejyxsqk5d) (version source revid:marko.makela@oracle.com-20100630093149-wmc37t128gic933v) (merge vers: 5.1.49) (pib:18)
[4 Aug 2010 8:02]
Bugs System
Pushed into mysql-trunk 5.6.1-m4 (revid:alik@ibmvm-20100804080001-bny5271e65xo34ig) (version source revid:marko.makela@oracle.com-20100630093149-wmc37t128gic933v) (merge vers: 5.1.49) (pib:18)
[4 Aug 2010 8:18]
Bugs System
Pushed into mysql-trunk 5.6.1-m4 (revid:alik@ibmvm-20100804081533-c1d3rbipo9e8rt1s) (version source revid:marko.makela@oracle.com-20100630093149-wmc37t128gic933v) (merge vers: 5.1.49) (pib:18)
[4 Aug 2010 9:01]
Bugs System
Pushed into mysql-next-mr (revid:alik@ibmvm-20100804081630-ntapn8bf9pko9vj3) (version source revid:marko.makela@oracle.com-20100630093149-wmc37t128gic933v) (pib:20)
[17 Aug 2010 20:22]
John Russell
As this isn't a fix to functionality, and this particular message seems to be fairly deep in the internals, I'm going to close without adding an entry to the change log in the doc.
[18 Aug 2010 11:14]
Mark Leith
Actually, this changes the output of SHOW ENGINE INNODB STATUS, so it should be documented, and the documentation that has any SHOW ENGINE INNODB STATUS output within it should be updated to reflect it. Before this change: ---------- SEMAPHORES ---------- OS WAIT ARRAY INFO: reservation count 491, signal count 485 Mutex spin waits 785, rounds 11067, OS waits 123 RW-shared spins 163, OS waits 177; RW-excl spins 2, OS waits 170 Spin rounds per wait: 14.10 mutex, 34.42 RW-shared, 2655.00 RW-excl After this change: ---------- SEMAPHORES ---------- OS WAIT ARRAY INFO: reservation count 2, signal count 2 Mutex spin waits 0, rounds 0, OS waits 0 RW-shared spins 2, rounds 60, OS waits 2 RW-excl spins 0, rounds 0, OS waits 0 Spin rounds per wait: 0.00 mutex, 30.00 RW-shared, 0.00 RW-excl
[18 Aug 2010 16:22]
John Russell
Added to change log for 5.5.6: The output from the SHOW ENGINE INNODB STATUS command now includes information about "spin rounds" for RW-locks (both shared and exclusive locks). Leaving the bug in documenting status for the moment, because instances of SHOW ENGINE INNODB STATUS have not been updated yet. Also, need to ensure there is a good explanation of the idea of "spin" terms such as spin rounds in the doc.
[1 Dec 2010 20:00]
John Russell
Only one example showing this level of detail in the Ref Man. Updated per Mark's example.
Description: The plugin now outputs the following line: Spin rounds per wait: 31.23 mutex, 17.82 RW-shared, 13.71 RW-excl These are the ratios between spin rounds to spin waits. For mutexes we report each data point, as such: Mutex spin waits 187325, rounds 5849403, OS waits 4117 However for RW locks, we do not expose the rounds variables (though the are still tracked internally); RW-shared spins 23255, OS waits 11027; RW-excl spins 16989, OS waits 4809 To be more consistent across all, we should expose spin rounds for each RW lock type too. How to repeat: N/A Suggested fix: === modified file 'storage/innobase/sync/sync0sync.c' --- storage/innobase/sync/sync0sync.c revid:vasil.dimov@oracle.com-20100617095953-0v2pan110jlxpeor +++ storage/innobase/sync/sync0sync.c 2010-06-23 09:17:42 +0000 @@ -1492,14 +1492,16 @@ fprintf(file, "Mutex spin waits %llu, rounds %llu, OS waits %llu\n" - "RW-shared spins %llu, OS waits %llu;" - " RW-excl spins %llu, OS waits %llu\n", + "RW-shared spins %llu, rounds %llu, OS waits %llu\n" + "RW-excl spins %llu, rounds %llu, OS waits %llu\n", mutex_spin_wait_count, mutex_spin_round_count, mutex_os_wait_count, rw_s_spin_wait_count, + rw_s_spin_round_count, rw_s_os_wait_count, rw_x_spin_wait_count, + rw_x_spin_round_count, rw_x_os_wait_count); fprintf(file,