linux-kernel - Re: [RFC PATCH 1/2] lib: debugobjects: export max loops counter

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Message-ID: <8ea5263b-6733-78fa-f6bd-331eedb39da5@redhat.com>
Date:   Mon, 27 Nov 2017 13:08:31 -0500
From:   Waiman Long <longman@...hat.com>
To:     Yang Shi <yang.s@...baba-inc.com>, tglx@...utronix.de
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 1/2] lib: debugobjects: export max loops counter

On 11/27/2017 12:53 PM, Yang Shi wrote:
> Hi Waiman & tglx,
>
> I'm not sure who is the maintainer for lib/debugobjects.c now, I'm
> supposed tglx still is, however, get_maintainer.pl told me Waiman is
> the most active developer of this, so added Waiman in this loop in
> case he didn't see the patches on LKML.
>
> Thanks,
> Yang
>
> On 11/17/17 11:43 AM, Yang Shi wrote:
>> Currently max chain counter is exported to sysfs, it just record the

It is the debugfs, which is different from sysfs.

>> counter of inner loop, however, there might be significant iterations of
>> external loop then it may take significant amount of time to finish all
>> of the checks. This may cuase lockup on !CONFIG_PREEMPT kernel build
>> occasionally.
>>
>> Record the counter of the max loops then export to sysfs so that the
>> user can be aware of the real overhead.
>>
>> Then the output of /sys/kernel/debug/debug_objects/stats looks like:
>>
>> max_chain     :121
>> max_loops     :543267
>> warnings      :0
>> fixups        :0
>> pool_free     :1764
>> pool_min_free :341
>> pool_used     :86438
>> pool_max_used :268887
>> objs_allocated:6068254
>> objs_freed    :5981076
>>
>> Signed-off-by: Yang Shi <yang.s@...baba-inc.com>

I have no objection to adding one more tracking count.

Cheers,
Longman