lockdep: Add nr_save_trace_invocations counter
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From: John Kacur on 23 Apr 2010 03:30 On Fri, 23 Apr 2010, Yong Zhang wrote: > On Thu, Apr 22, 2010 at 10:15:48PM +0200, John Kacur wrote: > > NOT FOR INCLUSION > > > > I created this patch as a result of Peter Zilstra's request to get more > > info from lockdep. This patch is not for inclusion, at least in its > > present form, because it adds some redunant info to /proc/lockdep_stats > > > > However, some of the fields are new, and it is worth examining, and / or > > applying if you are looking at the MAX_STACK_TRACE_ENTRIES too big > > problem. > > > > I generated this patch against a recent tip/master but it applies without > > conflicts to the latest rt kernel as well. Comments are welcome, in fact > > they are appreciated. > > > > >From 5181c0296dd1549e4e706ff25a4cd81a1d90137d Mon Sep 17 00:00:00 2001 > > From: John Kacur <jkacur(a)redhat.com> > > Date: Thu, 22 Apr 2010 17:02:42 +0200 > > Subject: [PATCH] lockdep: Add nr_save_trace_invocations counter > > > > Add the nr_save_trace_invocations counter which counts the number of > > time save_trace() is invoked when relevant for trace enteries. > > > > This means, those invocations from mark_lock() and add_lock_to_list() > > > > When called from mark_lock() we break it down into LOCKSTATE categories. > > > > Signed-off-by: John Kacur <jkacur(a)redhat.com> > > Just take a rough look at it. I don't think this can give more info. > > > +/* Calls to save_trace() from mark_lock() and add_lock_to_list() only*/ > > +unsigned long nr_save_trace_invocations; > > It will equal to nr_list_entries. > > > +unsigned long nr_save_trace_invocations_type[LOCK_USAGE_STATES]; > > And each item in this array will equal to nr_hardirq_[un]safe, > nr_softirq_[un]safe and such things under lockdep_stats_show(). Right? > > Thanks, > Yong > Hi Yong Some context here - Peter asked me to see if we could get some more detailed stats on why some configurations reach the MAX_STACK_TRACE_ENTRIES limit - whether the limit was really too low for some circumstances, or whether we were counting somethings unnecessarily. In any case, I stamped a big NOT FOR INCLUSION on my mail, because I noticed that somethings were redundant - albeit, obtained in a slightly different manner, however, not everything is redundant. In particular, nr_save_trace_invocations is NOT equal to nr_list_entries. You will see that reported in /proc/lockdep_stats as direct dependencies: 8752 [max: 16384] I have stack-trace invocations: 10888 from the same run. Still trying to figure out what the meaning is of that though to be honest. Here is a portion of the lockdep_stats, with all of the new fields and the redundant ones. stack-trace invocations: 10888 LOCK_USED_IN_HARDIRQ: 15 LOCK_USED_IN_HARDIRQ_READ: 0 LOCK_ENABLED_HARDIRQ: 543 LOCK_ENABLED_HARDIRQ_READ: 28 LOCK_USED_IN_SOFTIRQ: 0 LOCK_USED_IN_SOFTIRQ_READ: 0 LOCK_ENABLED_SOFTIRQ: 543 LOCK_ENABLED_SOFTIRQ_READ: 28 LOCK_USED_IN_RECLAIM_FS: 5 LOCK_USED_IN_RECLAIM_FS_READ: 0 LOCK_ENABLED_RECLAIM_FS: 95 LOCK_ENABLED_RECLAIM_FS_READ: 8 LOCK_USED: 871 combined max dependencies: 139841 hardirq-safe locks: 15 hardirq-unsafe locks: 543 softirq-safe locks: 0 softirq-unsafe locks: 543 irq-safe locks: 15 irq-unsafe locks: 543 hardirq-read-safe locks: 0 hardirq-read-unsafe locks: 28 softirq-read-safe locks: 0 softirq-read-unsafe locks: 28 irq-read-safe locks: 0 irq-read-unsafe locks: 28 So, you see that all of the reclaim fields are new, LOCK_USED_IN_RECLAIM_FS: 5 LOCK_USED_IN_RECLAIM_FS_READ: 0 LOCK_ENABLED_RECLAIM_FS: 95 LOCK_ENABLED_RECLAIM_FS_READ: 8 I can create a patch for inclusion that adds the reclaim fields, the question is, is the nr_save_trace_invocations a useful stat for us or not? Thanks -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Peter Zijlstra on 23 Apr 2010 04:10 On Fri, 2010-04-23 at 09:24 +0200, John Kacur wrote: > direct dependencies: 8752 [max: 16384] > I have > stack-trace invocations: 10888 > from the same run. > > Still trying to figure out what the meaning is of that though to be > honest. > > Here is a portion of the lockdep_stats, with all of the new fields and the > redundant ones. > > stack-trace invocations: 10888 > LOCK_USED_IN_HARDIRQ: 15 > LOCK_USED_IN_HARDIRQ_READ: 0 > LOCK_ENABLED_HARDIRQ: 543 > LOCK_ENABLED_HARDIRQ_READ: 28 > LOCK_USED_IN_SOFTIRQ: 0 > LOCK_USED_IN_SOFTIRQ_READ: 0 > LOCK_ENABLED_SOFTIRQ: 543 > LOCK_ENABLED_SOFTIRQ_READ: 28 > LOCK_USED_IN_RECLAIM_FS: 5 > LOCK_USED_IN_RECLAIM_FS_READ: 0 > LOCK_ENABLED_RECLAIM_FS: 95 > LOCK_ENABLED_RECLAIM_FS_READ: 8 > LOCK_USED: 871 8752+871+8+95+5+28+543+28+543+15=10888 So you get a stack-trace for each direct-dependency, and you get a stack-trace for each LOCK_state, the sum seems to match the total invocations. Non of these numbers look strange.. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Yong Zhang on 23 Apr 2010 04:10 On Fri, Apr 23, 2010 at 09:24:55AM +0200, John Kacur wrote: > Some context here - Peter asked me to see if we could get some more > detailed stats on why some configurations reach the > MAX_STACK_TRACE_ENTRIES limit - whether the limit was really too low for > some circumstances, or whether we were counting somethings unnecessarily. > > In any case, I stamped a big NOT FOR INCLUSION on my mail, because I > noticed that somethings were redundant - albeit, obtained in a slightly > different manner, however, not everything is redundant. > > In particular, nr_save_trace_invocations is NOT equal to nr_list_entries. > You will see that reported in /proc/lockdep_stats as > direct dependencies: 8752 [max: 16384] > I have > stack-trace invocations: 10888 > from the same run. I missed that nr_save_trace_invocations is also increased in inc_save_trace_invocations(). So nr_save_trace_invocations = nr_list_entries + sum of nr_save_trace_invocations_type[]. > > Still trying to figure out what the meaning is of that though to be > honest. > > Here is a portion of the lockdep_stats, with all of the new fields and the > redundant ones. > > stack-trace invocations: 10888 > LOCK_USED_IN_HARDIRQ: 15 > LOCK_USED_IN_HARDIRQ_READ: 0 > LOCK_ENABLED_HARDIRQ: 543 > LOCK_ENABLED_HARDIRQ_READ: 28 > LOCK_USED_IN_SOFTIRQ: 0 > LOCK_USED_IN_SOFTIRQ_READ: 0 > LOCK_ENABLED_SOFTIRQ: 543 > LOCK_ENABLED_SOFTIRQ_READ: 28 > LOCK_USED_IN_RECLAIM_FS: 5 > LOCK_USED_IN_RECLAIM_FS_READ: 0 > LOCK_ENABLED_RECLAIM_FS: 95 > LOCK_ENABLED_RECLAIM_FS_READ: 8 > LOCK_USED: 871 > combined max dependencies: 139841 > hardirq-safe locks: 15 > hardirq-unsafe locks: 543 > softirq-safe locks: 0 > softirq-unsafe locks: 543 > irq-safe locks: 15 > irq-unsafe locks: 543 > hardirq-read-safe locks: 0 > hardirq-read-unsafe locks: 28 > softirq-read-safe locks: 0 > softirq-read-unsafe locks: 28 > irq-read-safe locks: 0 > irq-read-unsafe locks: 28 > > So, you see that all of the reclaim fields are new, > LOCK_USED_IN_RECLAIM_FS: 5 > LOCK_USED_IN_RECLAIM_FS_READ: 0 > LOCK_ENABLED_RECLAIM_FS: 95 > LOCK_ENABLED_RECLAIM_FS_READ: 8 Yes, indeed, data in lockdep_stats_show() is out of time. So as Peter has said in another thread, we should add sample for RECLAIM_FS. > > I can create a patch for inclusion that adds the reclaim fields, the > question is, is the nr_save_trace_invocations a useful stat for us or not? Actually it's just a summation of the samples. I don't think it's necessary. Thanks, Yong -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Yong Zhang on 23 Apr 2010 04:10
On Fri, Apr 23, 2010 at 08:52:05AM +0200, Peter Zijlstra wrote: > On Fri, 2010-04-23 at 10:58 +0800, Yong Zhang wrote: > > > > > +unsigned long nr_save_trace_invocations_type[LOCK_USAGE_STATES]; > > > > And each item in this array will equal to nr_hardirq_[un]safe, > > nr_softirq_[un]safe and such things under lockdep_stats_show(). Right? > > Well, the stats for RECLAIM_FS as missing, so at the very least we need > to re-write lockdep_stats_show() to use the lockdep_states.h magic. Yeah, it's a good start point and will keep thing unifying in the future. Thanks, Yong -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |