linux-kernel - Re: [PATCH] crash_core: export vmemmap when CONFIG_SPARSEMEM

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Date: Thu, 21 Dec 2023 11:11:20 +0800
From: Shijie Huang <shijie@...eremail.onmicrosoft.com>
To: Baoquan He <bhe@...hat.com>, k-hagio-ab@....com
Cc: Huang Shijie <shijie@...amperecomputing.com>, lijiang@...hat.com,
 akpm@...ux-foundation.org, vgoyal@...hat.com, dyoung@...hat.com,
 kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
 patches@...erecomputing.com
Subject: Re: [PATCH] crash_core: export vmemmap when CONFIG_SPARSEMEM_VMEMMAP
 is enabled

Hi Baoquan,

在 2023/11/28 15:34, Baoquan He 写道:
> On 11/28/23 at 11:31am, Shijie Huang wrote:
>> 在 2023/11/28 11:25, Baoquan He 写道:
>>> On 11/27/23 at 11:18am, Shijie Huang wrote:
>>>> 在 2023/11/27 10:51, Baoquan He 写道:
>>>>> Hi,
>>>>>
>>>>> On 11/27/23 at 10:07am, Huang Shijie wrote:
>>>>>> In memory_model.h, if CONFIG_SPARSEMEM_VMEMMAP is configed,
>>>>>> kernel will use vmemmap to do the __pfn_to_page/page_to_pfn,
>>>>>> and kernel will not use the "classic sparse" to do the
>>>>>> __pfn_to_page/page_to_pfn.
>>>>>>
>>>>>> So export the vmemmap when CONFIG_SPARSEMEM_VMEMMAP is configed.
>>>>>> This makes the user applications (crash, etc) get faster
>>>>>> pfn_to_page/page_to_pfn operations too.
>>>>> Are there Crash or makedupfile patches posted yet to make use of this?
>>>> I have patches for Crash to use the 'vmemmap', but after this patch is
>>>> merged, I will send it out.
>>>>
>>>> (I think Kazu will not merge a crash patch which depends on a kernel patch
>>>> which is not merged.)
>>> Maybe post these userspace patches too so that Kazu can evaluat if those
>>> improvement is necessary?
>> No problem.  I will send out them later.
> Thank, Shijie. Let's wait and see if Kazu has any comment about these.


Kazu is waiting for this patch to be merged now:

https://lists.crash-utility.osci.io/archives/list/devel@lists.crash-utility.osci.io/thread/IJB54DIDWEJVCSCOLDYLC5NJ5AUIJZDP/


Thanks

Huang Shijie

>