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From: Peter Zijlstra <peterz@infradead.org>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, Dmitry Vyukov <dvyukov@google.com>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH v3] lockdep: Allow tuning tracing capacity constants.
Date: Wed, 18 Nov 2020 16:10:38 +0100	[thread overview]
Message-ID: <20201118151038.GX3121392@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1778f2e5-0a0c-2c6e-2c83-fe51d938e8a2@i-love.sakura.ne.jp>

On Wed, Nov 18, 2020 at 11:30:05PM +0900, Tetsuo Handa wrote:
> The problem is that we can't know what exactly is consuming these resources.
> My question is do you have a plan to make it possible to know what exactly is
> consuming these resources.

I'm pretty sure it's in /proc/lockdep* somewhere.

IIRC you were suffering from "MAX_LOCKDEP_ENTRIES too low!", which you
find in alloc_list_entry(), that's used in add_lock_to_list(), which in
turn is used in check_prev_add() to add to ->locks_after and
->locks_before.

/me frobs in lockdep_proc.c and finds l_show() uses locks_after,
l_show() is the implementation for /proc/lockdep.

So something like:

$ grep "^ ->" /proc/lockdep | wc -l
5064

Should be roughly half (it only shows the forward dependencies) the
number of list_entries used.

/proc/lockdep_stats: direct dependencies:                 11886 [max: 32768]

gives the number of list_entries used

Trick then is finding where they all go, because as you can see, my
machine is nowhere near saturated, even though it's been running a few
days.

So, go forth and analyize your problem.

  reply	other threads:[~2020-11-18 15:11 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-25  1:30 [PATCH] lockdep: Introduce CONFIG_LOCKDEP_LARGE Tetsuo Handa
2020-07-25  4:48 ` Dmitry Vyukov
2020-07-25  5:23   ` Tetsuo Handa
2020-08-04  2:36     ` Tetsuo Handa
2020-08-18  9:57       ` Dmitry Vyukov
2020-08-18 11:07         ` Tetsuo Handa
2020-08-18 12:02           ` Dmitry Vyukov
2020-08-18 12:59             ` Tetsuo Handa
2020-08-27 15:20 ` [PATCH v2] lockdep: Allow tuning tracing capacity constants Tetsuo Handa
2020-09-04 16:05   ` Tetsuo Handa
2020-09-16 11:28     ` Dmitry Vyukov
2020-09-16 11:50       ` peterz
2020-09-16 12:14         ` Dmitry Vyukov
2020-09-28  0:24           ` Tetsuo Handa
2020-09-28  5:12             ` Dmitry Vyukov
2020-10-10 12:58   ` [PATCH v3] " Tetsuo Handa
2020-10-18 13:02     ` Tetsuo Handa
2020-11-18 13:57       ` Tetsuo Handa
2020-11-18 14:23         ` Peter Zijlstra
2020-11-18 14:30           ` Tetsuo Handa
2020-11-18 15:10             ` Peter Zijlstra [this message]
2020-11-18 15:31               ` Tetsuo Handa
2020-11-19 12:33                 ` Dmitry Vyukov
2020-11-19 12:43                   ` Dmitry Vyukov
2020-11-19 12:49                     ` Dmitry Vyukov
2020-11-19 13:06                       ` Dmitry Vyukov
2020-11-19 13:45                         ` Tetsuo Handa
2020-11-19 14:05                           ` Dmitry Vyukov
     [not found]                             ` <CACT4Y+aNJmuhk0KicX4FzKW6PhawFBgvrC2gSJcWwUkR8VSSmg@mail.gmail.com>
2020-11-19 14:36                               ` Dmitry Vyukov
2020-11-19 18:08                                 ` Dmitry Vyukov
2020-11-20  9:22                                   ` Dmitry Vyukov
2020-11-20  9:27                                     ` Dmitry Vyukov
2020-11-22  1:56                                       ` Tetsuo Handa
2020-11-27  9:00                                         ` Dmitry Vyukov
2020-12-03 13:47                                           ` Tetsuo Handa
2020-12-04 14:35                                             ` Tetsuo Handa
2020-11-19 14:57                               ` Tetsuo Handa
2021-01-01  8:09     ` [PATCH v4] " Tetsuo Handa

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