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

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Message-ID: <20201204120816.GC10011@alpha.franken.de>
Date:   Fri, 4 Dec 2020 13:08:16 +0100
From:   Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To:     Jiaxun Yang <jiaxun.yang@...goat.com>
Cc:     Tiezhu Yang <yangtiezhu@...ngson.cn>, 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 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...

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]