linux-kernel - Re: [PATCH] MM: Support more pagesizes for MAP_HUGETLB/SHM

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Message-ID: <4FDC358F.6020905@jp.fujitsu.com>
Date:	Sat, 16 Jun 2012 16:28:15 +0900
From:	Kamezawa Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Andi Kleen <andi@...stfloor.org>
CC:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH] MM: Support more pagesizes for MAP_HUGETLB/SHM_HUGETLB
 v2

(2012/06/13 8:13), Andi Kleen wrote:
> From: Andi Kleen<ak@...ux.intel.com>
> 
> There was some desire in large applications using MAP_HUGETLB/SHM_HUGETLB
> to use 1GB huge pages on some mappings, and stay with 2MB on others. This
> is useful together with NUMA policy: use 2MB interleaving on some mappings,
> but 1GB on local mappings.
> 
> This patch extends the IPC/SHM syscall interfaces slightly to allow specifying
> the page size.
> 
> It borrows some upper bits in the existing flag arguments and allows encoding
> the log of the desired page size in addition to the *_HUGETLB flag.
> When 0 is specified the default size is used, this makes the change fully
> compatible.
> 
> Extending the internal hugetlb code to handle this is straight forward. Instead
> of a single mount it just keeps an array of them and selects the right
> mount based on the specified page size.
> 
> I also exported the new flags to the user headers
> (they were previously under __KERNEL__). Right now only symbols
> for x86 and some other architecture for 1GB and 2MB are defined.
> The interface should already work for all other architectures
> though.
> 
> v2: Port to new tree. Fix unmount.
> Signed-off-by: Andi Kleen<ak@...ux.intel.com>

I like this.

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

BTW, do you have any plan to implement 1GB page allocator ?
I wonder recent contiguous-memory-allocator works can be used for...




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