From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934981Ab1ETBUh (ORCPT ); Thu, 19 May 2011 21:20:37 -0400 Received: from mail-gx0-f174.google.com ([209.85.161.174]:45691 "EHLO mail-gx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934603Ab1ETBUf (ORCPT ); Thu, 19 May 2011 21:20:35 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=ZCa0Cfv74VEAOvycWtcV4WW71FnGJcbgrcAQ4DWD1VUvW3cTU0XjDLieGhuicKMTWE TC+6EglKq8OgvP3jqlGG39/BEV21Eq7w+hPURJIq8DM7PnrEE/NWYVJGgZeYFK2Av/8i v6cJbNo/TVtvB6Me5eUGDS4A5gprcsPrwXkdQ= MIME-Version: 1.0 In-Reply-To: <4DD4F6C1.5090701@gmail.com> References: <4DD4F6C1.5090701@gmail.com> Date: Fri, 20 May 2011 09:20:34 +0800 Message-ID: Subject: Re: [RESEND PATCH] Documentation: statistics about nested locks From: Yong Zhang To: Juri Lelli Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , trivial@kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id p4K1KoOK014773 On Thu, May 19, 2011 at 6:53 PM, Juri Lelli wrote: > Explain what the trailing "/1" on some lock class names of lock_stat output > means. > > Cc: Yong Zhang > Signed-off-by: Juri Lelli > Looks good. Reviewed-by: Yong Zhang > --- >  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          [] task_rq_lock+0x43/0x75 > +37                               &rq->lock            297          [] try_to_wake_up+0x127/0x25a > +38                               &rq->lock            360          [] select_task_rq_fair+0x1f0/0x74a > +39                               &rq->lock            428          [] scheduler_tick+0x46/0x1fb > +40                               --------- > +41                               &rq->lock             77          [] task_rq_lock+0x43/0x75 > +42                               &rq->lock            174          [] try_to_wake_up+0x127/0x25a > +43                               &rq->lock           4715          [] double_rq_lock+0x42/0x54 > +44                               &rq->lock            893          [] 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          [] double_rq_lock+0x4f/0x54 > +51                             ----------- > +52                             &rq->lock/1           5645          [] double_rq_lock+0x42/0x54 > +53                             &rq->lock/1           1224          [] schedule+0x157/0x7b8 > +54                             &rq->lock/1           4336          [] double_rq_lock+0x4f/0x54 > +55                             &rq->lock/1            181          [] 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 {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I