linux-kernel - Re: [PATCH 2/2] MIPS: Select ARCH_KEEP_MEMBLOCK to enable sysfs memblock debug

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Message-ID: <727e9b94-0a22-189f-4c65-4a6e8504013f@loongson.cn>
Date:   Sat, 5 Dec 2020 13:05:06 +0800
From:   Tiezhu Yang <yangtiezhu@...ngson.cn>
To:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Jiaxun Yang <jiaxun.yang@...goat.com>
Cc:     linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        Xuefeng Li <lixuefeng@...ngson.cn>
Subject: Re: [PATCH 2/2] MIPS: Select ARCH_KEEP_MEMBLOCK to enable sysfs
 memblock debug

On 12/04/2020 08:08 PM, Thomas Bogendoerfer wrote:
> On Thu, Dec 03, 2020 at 11:58:51AM +0800, Jiaxun Yang wrote:
>>
>> 在 2020/12/3 上午11:19, Tiezhu Yang 写道:
>>> In the current code, CONFIG_ARCH_KEEP_MEMBLOCK is not set for MIPS arch,
>>> memblock_discard() will discard memory and reserved arrays if they were
>>> allocated, select ARCH_KEEP_MEMBLOCK to give a chance to track "memory"
>>> and "reserved" memblocks after early boot, with this patch, we can see
>>> the following two sysfs interfaces under DEBUG_FS.
>>>
>>> /sys/kernel/debug/memblock/memory
>>> /sys/kernel/debug/memblock/reserved
>> Is this really necessary?
>> memblock data is not really necessary after boot for non-debug purpose.
>>
>> Given that MIPS is widely used in embedded systems which doesn't have much
>> memory, keeping unused data after boot is kinda unconvincing.
> about how much memory are talking here ?
>
>> If you intend to debug that please do it locally.
> maybe we can add a
>
> if DEBUG_KERNEL
>
> since enabling DEBUG_KERNEL will cost already some memory...

Yes, that makes sense.

If nobody has any objections, I will send v2 in the next week.

Thanks,
Tiezhu

>
> Thomas.
>