Messages in this thread | | | Date | Tue, 17 May 2011 10:00:12 +0800 | Subject | Re: [PATCH] Documentation: statistics about nested locks | From | Yong Zhang <> |
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On Mon, May 16, 2011 at 6:01 PM, Juri Lelli <juri.lelli@gmail.com> wrote: > 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. > > 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 first subclass (/1) of &rq->lock class,
Actually it's the second subclass because subclass starts from 0.
Thanks, Yong
> 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
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