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From: Yehuda Yitschak <yehuday@marvell.com>
To: "linux-mm@kvack.org" <linux-mm@kvack.org>
Cc: Shadi Ammouri <shadi@marvell.com>
Subject: [QUESTION] mmap of  device file with huge pages
Date: Tue, 9 Aug 2016 09:58:32 +0000	[thread overview]
Message-ID: <85d8c7bb8bcc4a30865a4512dd174cf8@IL-EXCH02.marvell.com> (raw)

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Hello everyone

I am trying mmap  kernel buffers associated with a device file (like /dev/mem) using huge pages.
I couldn't find any mechanism to do this.

On the kernel side I allocate a contiguous 2M buffer using alloc_pages.

A regular mmap with MAP_HUGETLB flag will only accept anonymous mappings or hugetlbfs files but not device files.
So, I think I need to make sure the mapping uses huge pages in my device file's mmap hook.
Usually these kind of mmap fops use remap_pfn_range but I couldn't find a way to make remap_pfn_range use huge pages.

I also tried to make Transparent huge pages recognize the mapping done with remap_pfn_range and collapse them to a huge page but that didn't work. Not sure why

I would appreciate any advice on this issue

Thanks !

-------------------
Yehuda Yitschak
Marvell Semiconductor Ltd.


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             reply	other threads:[~2016-08-09  9:58 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-09  9:58 Yehuda Yitschak [this message]
2016-08-09 17:39 ` [QUESTION] mmap of device file with huge pages Dave Hansen
2016-08-10  7:36   ` Yehuda Yitschak
2016-08-10 16:20     ` Dave Hansen

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