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Date:   Tue, 28 Nov 2023 11:25:56 +0800
From:   Baoquan He <bhe@redhat.com>
To:     Shijie Huang <shijie@amperemail.onmicrosoft.com>
Cc:     Huang Shijie <shijie@os.amperecomputing.com>, k-hagio-ab@nec.com,
        lijiang@redhat.com, akpm@linux-foundation.org, vgoyal@redhat.com,
        dyoung@redhat.com, kexec@lists.infradead.org,
        linux-kernel@vger.kernel.org, patches@amperecomputing.com
Subject: Re: [PATCH] crash_core: export vmemmap when CONFIG_SPARSEMEM_VMEMMAP
 is enabled
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References: <20231127020727.25296-1-shijie@os.amperecomputing.com>
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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?