linux-kernel - Re: [PATCH 2/4] alloc_contig_pages() find appropriate physical memory range

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Message-Id: <20101122091137.13da6a25.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Mon, 22 Nov 2010 09:11:37 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Minchan Kim <minchan.kim@...il.com>
Cc:	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Bob Liu <lliubbo@...il.com>, fujita.tomonori@....ntt.co.jp,
	m.nazarewicz@...sung.com, pawel@...iak.com, andi.kleen@...el.com,
	felipe.contreras@...il.com,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"kosaki.motohiro@...fujitsu.com" <kosaki.motohiro@...fujitsu.com>
Subject: Re: [PATCH 2/4] alloc_contig_pages() find appropriate physical
 memory range

On Mon, 22 Nov 2010 00:21:31 +0900
Minchan Kim <minchan.kim@...il.com> wrote:

> Acked-by: Minchan Kim <minchan.kim@...il.com>
> 
> Just some trivial comment below. 
> 
> Intentionally, I don't add Reviewed-by. 
> Instead of it, I add Acked-by since I support this work.
Thanks.

> 
> I reviewed your old version but have forgot it. :(

Sorry, I had a vacation ;(

> So I will have a time to review your code and then add Reviewed-by.
> 
> > ---
> >  mm/page_isolation.c |  146 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 146 insertions(+)
> > 
> > Index: mmotm-1117/mm/page_isolation.c
> > ===================================================================
> > --- mmotm-1117.orig/mm/page_isolation.c
> > +++ mmotm-1117/mm/page_isolation.c
> > @@ -7,6 +7,7 @@
> >  #include <linux/pageblock-flags.h>
> >  #include <linux/memcontrol.h>
> >  #include <linux/migrate.h>
> > +#include <linux/memory_hotplug.h>
> >  #include <linux/mm_inline.h>
> >  #include "internal.h"
> >  
> > @@ -250,3 +251,148 @@ int do_migrate_range(unsigned long start
> >  out:
> >  	return ret;
> >  }
> > +
> > +/*
> > + * Functions for getting contiguous MOVABLE pages in a zone.
> > + */
> > +struct page_range {
> > +	unsigned long base; /* Base address of searching contigouous block */
> > +	unsigned long end;
> > +	unsigned long pages;/* Length of contiguous block */
> > +	int align_order;
> > +	unsigned long align_mask;
> > +};
> > +
> > +int __get_contig_block(unsigned long pfn, unsigned long nr_pages, void *arg)
> > +{
> > +	struct page_range *blockinfo = arg;
> > +	unsigned long end;
> > +
> > +	end = pfn + nr_pages;
> > +	pfn = ALIGN(pfn, 1 << blockinfo->align_order);
> > +	end = end & ~(MAX_ORDER_NR_PAGES - 1);
> > +
> > +	if (end < pfn)
> > +		return 0;
> > +	if (end - pfn >= blockinfo->pages) {
> > +		blockinfo->base = pfn;
> > +		blockinfo->end = end;
> > +		return 1;
> > +	}
> > +	return 0;
> > +}
> > +
> > +static void __trim_zone(struct zone *zone, struct page_range *range)
> > +{
> > +	unsigned long pfn;
> > +	/*
> > + 	 * skip pages which dones'nt under the zone.
> 
>                             typo
> 
will fix.


> > + 	 * There are some archs which zones are not in linear layout.
> > +	 */
> > +	if (page_zone(pfn_to_page(range->base)) != zone) {
> > +		for (pfn = range->base;
> > +			pfn < range->end;
> > +			pfn += MAX_ORDER_NR_PAGES) {
> > +			if (page_zone(pfn_to_page(pfn)) == zone)
> > +				break;
> > +		}
> > +		range->base = min(pfn, range->end);
> > +	}
> > +	/* Here, range-> base is in the zone if range->base != range->end */
> > +	for (pfn = range->base;
> > +	     pfn < range->end;
> > +	     pfn += MAX_ORDER_NR_PAGES) {
> > +		if (zone != page_zone(pfn_to_page(pfn))) {
> > +			pfn = pfn - MAX_ORDER_NR_PAGES;
> > +			break;
> > +		}
> > +	}
> > +	range->end = min(pfn, range->end);
> > +	return;
> > +}
> > +
> > +/*
> > + * This function is for finding a contiguous memory block which has length
> > + * of pages and MOVABLE. If it finds, make the range of pages as ISOLATED
> > + * and return the first page's pfn.
> > + * This checks all pages in the returned range is free of Pg_LRU. To reduce
> 
>                                                               typo
> 
will lfix.

> > + * the risk of false-positive testing, lru_add_drain_all() should be called
> > + * before this function to reduce pages on pagevec for zones.
> > + */
> > +
> > +static unsigned long find_contig_block(unsigned long base,
> > +		unsigned long end, unsigned long pages,
> > +		int align_order, struct zone *zone)
> > +{
> > +	unsigned long pfn, pos;
> > +	struct page_range blockinfo;
> > +	int ret;
> > +
> > +	VM_BUG_ON(pages & (MAX_ORDER_NR_PAGES - 1));
> > +	VM_BUG_ON(base & ((1 << align_order) - 1));
> > +retry:
> > +	blockinfo.base = base;
> > +	blockinfo.end = end;
> > +	blockinfo.pages = pages;
> > +	blockinfo.align_order = align_order;
> > +	blockinfo.align_mask = (1 << align_order) - 1;
> > +	/*
> > +	 * At first, check physical page layout and skip memory holes.
> > +	 */
> > +	ret = walk_system_ram_range(base, end - base, &blockinfo,
> > +		__get_contig_block);
> 
> We need #include <linux/ioport.h>
> 

ok.

Thanks,
-Kame

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