linux-kernel - Re: [PATCH V2 0/2] Introduce slabinfo version 2.2

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Message-ID: <ad844581-2533-4a9c-8367-e14bf7b494d7@bytedance.com>
Date: Tue, 20 Feb 2024 15:09:46 +0800
From: Chengming Zhou <zhouchengming@...edance.com>
To: zhang fangzheng <fangzheng.zhang1003@...il.com>
Cc: Fangzheng Zhang <fangzheng.zhang@...soc.com>,
 Christoph Lameter <cl@...ux.com>, Pekka Enberg <penberg@...nel.org>,
 David Rientjes <rientjes@...gle.com>, Joonsoo Kim <iamjoonsoo.kim@....com>,
 Andrew Morton <akpm@...ux-foundation.org>, Vlastimil Babka <vbabka@...e.cz>,
 Roman Gushchin <roman.gushchin@...ux.dev>,
 Hyeonggon Yoo <42.hyeyoo@...il.com>, Greg KH <gregkh@...uxfoundation.org>,
 linux-mm@...ck.org, linux-kernel@...r.kernel.org, tkjos@...gle.com,
 Yuming Han <yuming.han@...soc.com>, Chunyan Zhang <zhang.lyra@...il.com>
Subject: Re: [PATCH V2 0/2] Introduce slabinfo version 2.2

On 2024/2/20 14:25, zhang fangzheng wrote:
> On Mon, Feb 19, 2024 at 7:29 PM Chengming Zhou
> <zhouchengming@...edance.com> wrote:
>>
>> On 2024/2/19 11:19, Fangzheng Zhang wrote:
>>> Hi all,
>>>
>>> This series introduces slabinfo version 2.2 to users.
>>> In slabinfo V2.2, we added a slabreclaim column to
>>> record whether each slab pool is of reclaim type.
>>> This will be more conducive for users to obtain
>>> the type of each slabdata more intuitively than through
>>> the interface /sys/kernel/slab/$cache/reclaim_account.
>>
>> I want to recommend a better tool: drgn[1] for these tasks, instead of changing
>> the output format of /proc/slabinfo, which may break existing userspace tools.
>>
>> [1] https://drgn.readthedocs.io/en/latest/index.html#
>>
> 
> Thank you very much for providing a new way.
> I have the following three questions about the new tool you provided:
> ---- 1. From the introduction, the tool is described as an alternative
> to the crash utility.
>           Will the permission requirements have different effects when
> used, user or userdebug?
> ----  2. The 'Helpers' chapter introduces the simple use of
> common.memory, but there is no output example.
>            It involves the use of slab objects, but it also needs to
> provide a specific slab_cache_name,
>            which cannot give an intuitive overall information like
> proc/slabinfo.

You can of course use drgn to iterate over all slabs by using the global
"slab_caches" list. (All kernel space is at your hand.)

>            I guess it is difficult to achieve direct output of slab
> type (reclaim or unreclaim). I don’t know, right?

It's easy for drgn to inspect each slab's information.

> ---- 3. Regarding the supported versions, is it supported for both
> arm/arm64? I don't seem to have seen any similar instructions.
> Finally, I would like to express my gratitude again. This tool will be
> very helpful for me in other future work.

Please check https://github.com/osandov/drgn for details.

Thanks.