linux-kernel - Re: [RESEND PATCH 00/10] memblock: introduce memsize showing reserved memory

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Date: Tue, 21 May 2024 10:31:31 +0300
From: Mike Rapoport <rppt@...nel.org>
To: Jaewon Kim <jaewon31.kim@...sung.com>
Cc: "vbabka@...e.cz" <vbabka@...e.cz>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"jaewon31.kim@...il.com" <jaewon31.kim@...il.com>,
	"tkjos@...gle.com" <tkjos@...gle.com>
Subject: Re: [RESEND PATCH 00/10] memblock: introduce memsize showing
 reserved memory

On Tue, May 21, 2024 at 11:53:29AM +0900, Jaewon Kim wrote:
> >--------- Original Message ---------
> >Sender : 김재원 <jaewon31.kim@...sung.com>System Performance Lab.(MX)/삼성전자
> >Date   : 2024-05-21 11:40 (GMT+9)
> >Title  : [RESEND PATCH 00/10] memblock: introduce memsize showing reserved memory
> >?
> >Some of memory regions can be reserved for a specific purpose. They are
> >usually defined through reserved-memory in device tree. If only size
> >without address is specified in device tree, the address of the region
> >will be determined at boot time.
> >
> >We may find the address of the memory regions through booting log, but
> >it does not show all. And it could be hard to catch the very beginning
> >log. The memblock_dump_all shows all memblock status but it does not
> >show region name and its information is difficult to summarize.
> >
> >This patch introduce a debugfs node, memblock/memsize, to see reserved
> >memory easily.
> >
> >Here's an example
> >
> >$ cat debugfs/memblock/memsize
> >
> >0x0000000000000000-0x0000000000000000 0x02000000 (?  32768 KB )?  map reusable linux,cma
> >0x0000000000000000-0x0000000000000000 0x01000000 (?  16384 KB )?  map reusable vxxxxx
> >...
> >0x0000000000000000-0x0000000000000000 0x004e0000 (? ? 4992 KB ) nomap unusable unknown
> >0x0000000000000000-0x0000000000000000 0x00400000 (? ? 4096 KB ) nomap unusable cxxxxx
> >0x0000000000000000-0x0000000000000000 0x00e00000 (?  14336 KB ) nomap unusable gxxxxx
> >
> >Reserved? ? : 1223856 KB
> > .kernel? ? :? 275208 KB
> >? .text? ?  :?  16576 KB
> >? .rwdata?  :? ? 1963 KB
> >? .rodata?  :?  11920 KB
> >? .bss? ? ? :? ? 2450 KB
> >? .memmap?  :? 186368 KB
> >? .etc? ? ? :?  55933 KB
> > .unusable? :? 948648 KB
> >System? ? ? : 11359056 KB
> > .common? ? : 10306384 KB
> > .reusable? : 1052672 KB
> >Total? ? ?  : 12582912 KB ( 12288.00 MB )
> >
> >Jaewon Kim (10):
> >? memblock: introduce memsize showing reserved memory
> >? memblock: detect hidden memory hole size
> >? memblock: handle overlapped reserved memory region
> >? memblock: take a region intersecting an unknown region
> >? memblock: track memblock changed at early param
> >? memblock: recognize late freed size by checking PageReserved
> >? memblock: track kernel size on memsize
> >? memblock: print memsize summary information
> >? memblock: print kernel internal size
> >? memblock: support memsize reusable to consider as reusable
> >
> > drivers/of/fdt.c? ? ? ? ? ?  |? 11 +
> > drivers/of/of_reserved_mem.c |? 12 +-
> > include/linux/memblock.h? ?  |? 29 ++
> > init/main.c? ? ? ? ? ? ? ? ? |? 13 +-
> > kernel/dma/contiguous.c? ? ? |?  9 +-
> > mm/Kconfig? ? ? ? ? ? ? ? ?  |? 16 ++
> > mm/memblock.c? ? ? ? ? ? ? ? | 502 ++++++++++++++++++++++++++++++++++-
> > mm/mm_init.c? ? ? ? ? ? ? ?  |?  6 +-
> > mm/page_alloc.c? ? ? ? ? ? ? |? 10 +-
> > 9 files changed, 597 insertions(+), 11 deletions(-)
> >
> >-- 
> >2.25.1
> 
> Hello Mike 
> 
> This is actually RESEND as it was introduced 2 years ago.
> Please refer to https://lore.kernel.org/linux-mm/YkQB6Ah603yPR3qf@kernel.org/#t
> 
> > But you never provided details about *why* you want this information exposed.
> 
> For your question, I'd like to say ;
> We can see the same format and exact information between different version of kernel status.
> 
> 1) Internally we can check if the reserved memory changes.
> 2) Externally we can communicate between chipset vendors and OEM, with a same format.

Why the existing debugfs interface is not sufficient?
 
> This helps us to communitcate well, to easily detect changes or just to see differences.
> 
> Jaewon Kim
> 

-- 
Sincerely yours,
Mike.