Documentation: statistics about nested locks
PATCH 1/1 Documentation: statistics about nested locks
Hi all,
just a little patch to the Documentation. I had some trouble understanding the trailing "/1" on some lock class names of lock_stat output, so I added something on this inside lockstat documentation.
--- Documentation/lockstat.txt | 36 ++++++++++++++++++++++++++++++++++-- 1 files changed, 34 insertions(+), 2 deletions(-)
Documentation/lockstat.txt +34 -2
@@ -12,8 +12,9 @@ Because things like lock contention can severely impact performance. - HOW Lockdep already has hooks in the lock functions and maps lock instances to -lock classes. We build on that. The graph below shows the relation between -the lock functions and the various hooks therein. +lock classes. We build on that (see Documentation/lockdep-design.txt). +The graph below shows the relation between the lock functions and the various +hooks therein. __acquire |
@@ -128,6 +129,37 @@ points are the points we're contending with. The integer part of the time values is in us. +Dealing with nested locks, subclasses may appear: + +32............................................................................................................................................................................................... +33 +34 &rq->lock: 13128 13128 0.43 190.53 103881.26 97454 3453404 0.00 401.11 13224683.11 +35 --------- +36 &rq->lock 645 [<ffffffff8103bfc4>] task_rq_lock+0x43/0x75 +37 &rq->lock 297 [<ffffffff8104ba65>] try_to_wake_up+0x127/0x25a +38 &rq->lock 360 [<ffffffff8103c4c5>] select_task_rq_fair+0x1f0/0x74a +39 &rq->lock 428 [<ffffffff81045f98>] scheduler_tick+0x46/0x1fb +40 --------- +41 &rq->lock 77 [<ffffffff8103bfc4>] task_rq_lock+0x43/0x75 +42 &rq->lock 174 [<ffffffff8104ba65>] try_to_wake_up+0x127/0x25a +43 &rq->lock 4715 [<ffffffff8103ed4b>] double_rq_lock+0x42/0x54 +44 &rq->lock 893 [<ffffffff81340524>] schedule+0x157/0x7b8 +45 +46............................................................................................................................................................................................... +47 +48 &rq->lock/1: 11526 11488 0.33 388.73 136294.31 21461 38404 0.00 37.93 109388.53 +49 ----------- +50 &rq->lock/1 11526 [<ffffffff8103ed58>] double_rq_lock+0x4f/0x54 +51 ----------- +52 &rq->lock/1 5645 [<ffffffff8103ed4b>] double_rq_lock+0x42/0x54 +53 &rq->lock/1 1224 [<ffffffff81340524>] schedule+0x157/0x7b8 +54 &rq->lock/1 4336 [<ffffffff8103ed58>] double_rq_lock+0x4f/0x54 +55 &rq->lock/1 181 [<ffffffff8104ba65>] try_to_wake_up+0x127/0x25a + +Line 48 shows statistics for the first subclass (/1) of &rq->lock class, since +in this case, as line 50 suggests, double_rq_lock actually acquires a nested +lock of two spinlocks. + View the top contending locks:
# grep : /proc/lock_stat | head
Signature · 1 line
1.7.4.1
Quoted 3 lines · Juri Lelli
+The graph below shows the relation between the lock functions and the various
+hooks therein.
That smells like the patch has whitespace damage..
Quoted 6 lines · Peter Zijlstra
Quoted 3 lines · Juri Lelli
+The graph below shows the relation between the lock functions and the various
+hooks therein.That smells like the patch has whitespace damage..
Yeah, Documentation/email-clients.txt might help there.
Thanks,
Ingo
Sorry for my mistake with the email client and thanks for the hint! May I resend a (I hope) corrected version of this small patch with the revision made by Yong?
Quoted 10 lines · Ingo Molnar
Quoted 6 lines · Peter Zijlstra
Quoted 3 lines · Juri Lelli
+The graph below shows the relation between the lock functions and the various
+hooks therein.That smells like the patch has whitespace damage..
Quoted 5 lines
Yeah,
Documentation/email-clients.txtmight help there.Thanks,
Ingo
Thanks,
Juri
Quoted 3 lines · Juri Lelli
Sorry for my mistake with the email client and thanks for the hint! May I resend a (I hope) corrected version of this small patch with the revision made by Yong?
No problem on my side :)
Thanks,
Yong
Quoted 22 lines · Ingo Molnar
Quoted 10 lines · Peter Zijlstra
Quoted 7 lines · Juri Lelli
Quoted 3 lines
+The graph below shows the relation between the lock functions and the various
+hooks therein.That smells like the patch has whitespace damage..
Quoted 5 lines
Yeah,
Documentation/email-clients.txtmight help there.Thanks,
Ingo
Thanks,
Juri
Signature · 1 line
Only stand for myself
Quoted 76 lines · Juri Lelli
Hi all,
just a little patch to the Documentation. I had some trouble understanding the trailing "/1" on some lock class names oflock_statoutput, so I added something on this inside lockstat documentation.Signed-off-by Juri Lelli <[email protected]>---
Documentation/lockstat.txt | 36 ++++++++++++++++++++++++++++++++++--1 files changed, 34 insertions(+), 2 deletions(-)Documentation/lockstat.txt +0
-0@@ -12,8 +12,9 @@ Because things like lock contention can severely impactperformance.
- HOWLockdep already has hooks in the lock functions and maps lock instances to
Documentation/lockstat.txt +2
-2-lock classes. We build on that. The graph below shows the relation between -the lock functions and the various hooks therein. +lock classes. We build on that (see Documentation/lockdep-design.txt). +The graph below shows the relation between the lock functions and thevarious
+hooks therein.
__acquire
|Documentation/lockstat.txt +0
-0@@ -128,6 +129,37 @@ points are the points we're contending with.The integer part of the time values is in us.
Documentation/lockstat.txt +5
-0+Dealing with nested locks, subclasses may appear: + +32............................................................................................................................................................................................... +33 +34 &rq->lock: 13128 131280.43 190.53 103881.26 97454 3453404 0.00
401.11 13224683.11
+35 ---------
+36&rq->lock645
[<ffffffff8103bfc4>]task_rq_lock+0x43/0x75
+37&rq->lock297
[<ffffffff8104ba65>]try_to_wake_up+0x127/0x25a
+38&rq->lock360
[<ffffffff8103c4c5>]select_task_rq_fair+0x1f0/0x74a
+39&rq->lock428
[<ffffffff81045f98>]scheduler_tick+0x46/0x1fb
+40 ---------
+41&rq->lock77
[<ffffffff8103bfc4>]task_rq_lock+0x43/0x75
+42&rq->lock174
[<ffffffff8104ba65>]try_to_wake_up+0x127/0x25a
+43&rq->lock4715
[<ffffffff8103ed4b>]double_rq_lock+0x42/0x54
+44&rq->lock893
[<ffffffff81340524>]schedule+0x157/0x7b8
+45 +46............................................................................................................................................................................................... +47
+48 &rq->lock/1: 11526 11488
0.33 388.73 136294.31 21461 38404 0.00
37.93 109388.53
+49 -----------
+50 &rq->lock/1 11526
[<ffffffff8103ed58>]double_rq_lock+0x4f/0x54
+51 -----------
+52 &rq->lock/1 5645
[<ffffffff8103ed4b>]double_rq_lock+0x42/0x54
+53 &rq->lock/1 1224
[<ffffffff81340524>]schedule+0x157/0x7b8
+54 &rq->lock/1 4336
[<ffffffff8103ed58>]double_rq_lock+0x4f/0x54
+55 &rq->lock/1 181
[<ffffffff8104ba65>]try_to_wake_up+0x127/0x25a
Documentation/lockstat.txt
Quoted 2 lines
Documentation/lockstat.txt +2
-0+ +Line 48 shows statistics for the first subclass (/1) of &rq->lock class,
Actually it's the second subclass because subclass starts from 0.
Thanks,
Yong
Quoted 11 lines
since
+in this case, as line 50 suggests,double_rq_lockactually acquires a nestedDocumentation/lockstat.txt +2
-0+lock of two spinlocks. +View the top contending locks:
# grep : /proc/lock_stat | head -- 1.7.4.1
Signature · 2 lines
Only stand for myself
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