[RESEND PATCH] Documentation: statistics about nested locks

[RESEND PATCH] Documentation: statistics about nested locks

[Juri Lelli]

Explain what the trailing "/1" on some lock class names of lock_stat output
means.

Cc: Yong Zhang <yong.zhang0@gmail.com>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>

---
 Documentation/lockstat.txt |   36 ++++++++++++++++++++++++++++++++++--
 1 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/Documentation/lockstat.txt b/Documentation/lockstat.txt
index 65f4c79..75eeb65 100644
--- a/Documentation/lockstat.txt
+++ b/Documentation/lockstat.txt
@@ -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 second subclass (/1) of &rq->lock class
+(subclass starts from 0), 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
-- 
1.7.4.1

Re: [RESEND PATCH] Documentation: statistics about nested locks

[Peter Zijlstra]

On Thu, 2011-05-19 at 12:53 +0200, Juri Lelli wrote:
> Explain what the trailing "/1" on some lock class names of lock_stat output
> means.

great, this applies without problems, thanks!

Re: [RESEND PATCH] Documentation: statistics about nested locks

[Yong Zhang]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset=UTF-8, Size: 4841 bytes --]

On Thu, May 19, 2011 at 6:53 PM, Juri Lelli <juri.lelli@gmail.com> wrote:
> Explain what the trailing "/1" on some lock class names of lock_stat output
> means.
>
> Cc: Yong Zhang <yong.zhang0@gmail.com>
> Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
>

Looks good.

Reviewed-by: Yong Zhang <yong.zhang0@gmail.com>

> ---
>  Documentation/lockstat.txt |   36 ++++++++++++++++++++++++++++++++++--
>  1 files changed, 34 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/lockstat.txt b/Documentation/lockstat.txt
> index 65f4c79..75eeb65 100644
> --- a/Documentation/lockstat.txt
> +++ b/Documentation/lockstat.txt
> @@ -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 second subclass (/1) of &rq->lock class
> +(subclass starts from 0), 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
> --
> 1.7.4.1
>



-- 
Only stand for myself
ÿôèº{.nÇ+‰·Ÿ®‰­†+%ŠËÿ±éݶ\x17¥Šwÿº{.nÇ+‰·¥Š{±þG«éÿŠ{ayº\x1dʇڙë,j\a­¢f£¢·hšïêÿ‘êçz_è®\x03(­éšŽŠÝ¢j"ú\x1a¶^[m§ÿÿ¾\a«þG«éÿ¢¸?™¨è­Ú&£ø§~á¶iO•æ¬z·švØ^\x14\x04\x1a¶^[m§ÿÿÃ\fÿ¶ìÿ¢¸?–I¥

[tip:core/urgent] Documentation: Add statistics about nested locks

[tip-bot for Juri Lelli]

Commit-ID:  f62508f68d04adefc4cf9b0177ba02c8818b3eec
Gitweb:     http://git.kernel.org/tip/f62508f68d04adefc4cf9b0177ba02c8818b3eec
Author:     Juri Lelli <juri.lelli@gmail.com>
AuthorDate: Thu, 19 May 2011 12:53:53 +0200
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Sat, 28 May 2011 17:03:29 +0200

Documentation: Add statistics about nested locks

Explain what the trailing "/1" on some lock class names of
lock_stat output means.

Reviewed-by: Yong Zhang <yong.zhang0@gmail.com>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4DD4F6C1.5090701@gmail.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 Documentation/lockstat.txt |   36 ++++++++++++++++++++++++++++++++++--
 1 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/Documentation/lockstat.txt b/Documentation/lockstat.txt
index 9c0a80d..cef00d4 100644
--- a/Documentation/lockstat.txt
+++ b/Documentation/lockstat.txt
@@ -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 second subclass (/1) of &rq->lock class
+(subclass starts from 0), 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