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

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Date:   Tue, 28 Nov 2017 02:53:15 +0800
From:   "Yang Shi" <yang.s@...baba-inc.com>
To:     Waiman Long <longman@...hat.com>, tglx@...utronix.de
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 1/2] lib: debugobjects: export max loops counter



On 11/27/17 10:08 AM, Waiman Long wrote:
> 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.

Will correct it.

> 
>>> 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.

Thanks.

Yang

> 
> Cheers,
> Longman
>