linux-kernel - Re: [RFC PATCH 1/3] proc/meminfo: introduce extra meminfo

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Date:   Wed, 11 Mar 2020 20:35:50 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     Jaewon Kim <jaewon31.kim@...sung.com>
Cc:     akpm@...ux-foundation.org, labbott@...hat.com,
        sumit.semwal@...aro.org, minchan@...nel.org, ngupta@...are.org,
        sergey.senozhatsky.work@...il.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, jaewon31.kim@...il.com
Subject: Re: [RFC PATCH 1/3] proc/meminfo: introduce extra meminfo

On Wed, Mar 11, 2020 at 12:44:39PM +0900, Jaewon Kim wrote:
> Provide APIs to drivers so that they can show its memory usage on
> /proc/meminfo.
> 
> int register_extra_meminfo(atomic_long_t *val, int shift,
> 			   const char *name);
> int unregister_extra_meminfo(atomic_long_t *val);

> +			show_val_kb(m, memtemp->name_pad, nr_page);

I have 3 issues.

Can this be printed without "KB" piece and without useless whitespace,
like /proc/vmstat does?

I don't know how do you parse /proc/meminfo.
Do you search for specific string or do you use some kind of map[k] = v
interface?

2) zsmalloc can create top-level symlink and resolve it to necessary value.
It will be only 1 readlink(2) system call to fetch it.

3) android can do the same

For simple values there is no need to register stuff and create
mini subsystems.

	/proc/alexey