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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: Wed, 5 Feb 2020 08:59:22 -0500	[thread overview]
Message-ID: <f475cd25-2b63-39bc-c18c-14ac7274428b@redhat.com> (raw)
In-Reply-To: <20200205094153.GH14879@hirez.programming.kicks-ass.net>

On 2/5/20 4:41 AM, Peter Zijlstra wrote:
> On Tue, Feb 04, 2020 at 11:45:15AM -0500, Waiman Long wrote:
>> 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
>>  
> Sure, also I tihnk the compiler is unhappy about %lu vs 'unsigned int'
> for some of them.
>
Yes, I found that after I compiled the code :-)

Cheers,
Longman


  reply	other threads:[~2020-02-05 13:59 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
2020-02-05  9:41       ` Peter Zijlstra
2020-02-05 13:59         ` Waiman Long [this message]
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

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