linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Waiman Long <longman@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>,
	linux-kernel@vger.kernel.org,
	Bart Van Assche <bvanassche@acm.org>
Subject: Re: [PATCH v5 6/7] locking/lockdep: Reuse freed chain_hlocks entries
Date: Tue, 4 Feb 2020 11:45:15 -0500	[thread overview]
Message-ID: <8fd7ce61-d8eb-6bde-7d41-54b9920e3e39@redhat.com> (raw)
In-Reply-To: <20200204123629.GO14914@hirez.programming.kicks-ass.net>

On 2/4/20 7:36 AM, Peter Zijlstra wrote:
> --- a/kernel/locking/lockdep_proc.c
> +++ b/kernel/locking/lockdep_proc.c
> @@ -278,9 +278,11 @@ static int lockdep_stats_show(struct seq
>  #ifdef CONFIG_PROVE_LOCKING
>  	seq_printf(m, " dependency chains:             %11lu [max: %lu]\n",
>  			lock_chain_count(), MAX_LOCKDEP_CHAINS);
> -	seq_printf(m, " dependency chain hlocks:       %11lu [max: %lu]\n",
> -			MAX_LOCKDEP_CHAIN_HLOCKS - nr_free_chain_hlocks,
> +	seq_printf(m, " dependency chain hlocks used:  %11lu [max: %lu]\n",
> +			MAX_LOCKDEP_CHAIN_HLOCKS - (nr_free_chain_hlocks - nr_lost_chain_hlocks),
>  			MAX_LOCKDEP_CHAIN_HLOCKS);
> +	seq_printf(m, " dependency chain hlocks free:  %11lu\n", nr_free_chain_hlocks);
> +	seq_printf(m, " dependency chain hlocks lost:  %11lu\n", nr_lost_chain_hlocks);

I do have some comments on this. There are three buckets now - free,
lost, used. They add up to MAX_LOCKDEP_CHAIN_HLOCKS. I don't think we
need to list all three. We can compute the third one by subtracting max
from the other two.

Something like:

diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c
index 14932ea50317..6fe6a21c58d3 100644
--- a/kernel/locking/lockdep_proc.c
+++ b/kernel/locking/lockdep_proc.c
@@ -278,9 +278,12 @@ static int lockdep_stats_show(struct seq_file *m,
void *v)
 #ifdef CONFIG_PROVE_LOCKING
        seq_printf(m, " dependency chains:             %11lu [max: %lu]\n",
                        lock_chain_count(), MAX_LOCKDEP_CHAINS);
-       seq_printf(m, " dependency chain hlocks:       %11lu [max: %lu]\n",
-                       MAX_LOCKDEP_CHAIN_HLOCKS - nr_free_chain_hlocks,
+       seq_printf(m, " dependency chain hlocks used:  %11lu [max: %lu]\n",
+                       MAX_LOCKDEP_CHAIN_HLOCKS -
+                       (nr_free_chain_hlocks + nr_lost_chain_hlocks),
                        MAX_LOCKDEP_CHAIN_HLOCKS);
+       seq_printf(m, " dependency chain hlocks lost:  %11lu\n",
+                       nr_lost_chain_hlocks);
 #endif
 
 #ifdef CONFIG_TRACE_IRQFLAGS

Cheers,
Longman


  parent reply	other threads:[~2020-02-04 16:45 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-03 16:41 [PATCH v5 0/7] locking/lockdep: Reuse zapped chain_hlocks entries Waiman Long
2020-02-03 16:41 ` [PATCH v5 1/7] locking/lockdep: Decrement irq context counters when removing lock chain Waiman Long
2020-02-03 16:41 ` [PATCH v5 2/7] locking/lockdep: Display irq_context names in /proc/lockdep_chains Waiman Long
2020-02-03 16:41 ` [PATCH v5 3/7] locking/lockdep: Track number of zapped classes Waiman Long
2020-02-03 16:41 ` [PATCH v5 4/7] locking/lockdep: Throw away all lock chains with zapped class Waiman Long
2020-02-03 16:41 ` [PATCH v5 5/7] locking/lockdep: Track number of zapped lock chains Waiman Long
2020-02-03 16:41 ` [PATCH v5 6/7] locking/lockdep: Reuse freed chain_hlocks entries Waiman Long
2020-02-04 12:36   ` Peter Zijlstra
2020-02-04 14:54     ` Waiman Long
2020-02-04 16:45     ` Waiman Long [this message]
2020-02-05  9:41       ` Peter Zijlstra
2020-02-05 13:59         ` Waiman Long
2020-02-04 15:42   ` Peter Zijlstra
2020-02-04 16:12     ` Waiman Long
2020-02-04 16:26       ` Waiman Long
2020-02-04 16:57         ` Waiman Long
2020-02-05  9:48           ` Peter Zijlstra
2020-02-05 14:03             ` Waiman Long
2020-02-03 16:41 ` [PATCH v5 7/7] locking/lockdep: Add a fast path for chain_hlocks allocation Waiman Long
2020-02-04 12:47   ` Peter Zijlstra
2020-02-04 15:07     ` Waiman Long
2020-02-04 13:18   ` Peter Zijlstra
2020-02-04 13:44     ` Peter Zijlstra
2020-02-04 18:02       ` Waiman Long

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=8fd7ce61-d8eb-6bde-7d41-54b9920e3e39@redhat.com \
    --to=longman@redhat.com \
    --cc=bvanassche@acm.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    --cc=will.deacon@arm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).