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Date: Mon, 22 Nov 2010 02:30:39 +0200 From: Felipe Contreras <felipe.contreras@...il.com> To: Andrew Morton <akpm@...ux-foundation.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>, "linux-mm@...ck.org" <linux-mm@...ck.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, minchan.kim@...il.com, Bob Liu <lliubbo@...il.com>, fujita.tomonori@....ntt.co.jp, m.nazarewicz@...sung.com, pawel@...iak.com, andi.kleen@...el.com, "kosaki.motohiro@...fujitsu.com" <kosaki.motohiro@...fujitsu.com> Subject: Re: [PATCH 0/4] big chunk memory allocator v4 On Fri, Nov 19, 2010 at 10:56 PM, Andrew Morton <akpm@...ux-foundation.org> wrote: > On Fri, 19 Nov 2010 17:10:33 +0900 > KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> wrote: > >> Hi, this is an updated version. >> >> No major changes from the last one except for page allocation function. >> removed RFC. >> >> Order of patches is >> >> [1/4] move some functions from memory_hotplug.c to page_isolation.c >> [2/4] search physically contiguous range suitable for big chunk alloc. >> [3/4] allocate big chunk memory based on memory hotplug(migration) technique >> [4/4] modify page allocation function. >> >> For what: >> >> I hear there is requirements to allocate a chunk of page which is larger than >> MAX_ORDER. Now, some (embeded) device use a big memory chunk. To use memory, >> they hide some memory range by boot option (mem=) and use hidden memory >> for its own purpose. But this seems a lack of feature in memory management. Actually, now that's not needed any more by using memblock: http://article.gmane.org/gmane.linux.ports.arm.omap/44978 >> This patch adds >> alloc_contig_pages(start, end, nr_pages, gfp_mask) >> to allocate a chunk of page whose length is nr_pages from [start, end) >> phys address. This uses similar logic of memory-unplug, which tries to >> offline [start, end) pages. By this, drivers can allocate 30M or 128M or >> much bigger memory chunk on demand. (I allocated 1G chunk in my test). >> >> But yes, because of fragmentation, this cannot guarantee 100% alloc. >> If alloc_contig_pages() is called in system boot up or movable_zone is used, >> this allocation succeeds at high rate. > > So this is an alternatve implementation for the functionality offered > by Michal's "The Contiguous Memory Allocator framework". > >> I tested this on x86-64, and it seems to work as expected. But feedback from >> embeded guys are appreciated because I think they are main user of this >> function. > > From where I sit, feedback from the embedded guys is *vital*, because > they are indeed the main users. > > Michal, I haven't made a note of all the people who are interested in > and who are potential users of this code. Your patch series has a > billion cc's and is up to version 6. Could I ask that you review and > test this code, and also hunt down other people (probably at other > organisations) who can do likewise for us? Because until we hear from > those people that this work satisfies their needs, we can't really > proceed much further. As I've explained before, a contiguous memory allocator would be nice, but on ARM many drivers not only need contiguous memory, but non-cacheable, and this requires removing the memory from normal kernel mapping in early boot. Cheers. -- Felipe Contreras -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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