Re: [Patch1/4]: fake numa for x86_64 patch

From: Mel Gorman
Date: Mon Nov 27 2006 - 08:18:56 EST


On Wed, 22 Nov 2006, Rohit Seth wrote:

This patch provides a IO hole size in a given address range.


Hi,

This patch reintroduces a function that doubles up what absent_pages_in_range(start_pfn, end_pfn). I recognise you do this because you are interested in hole sizes before add_active_range() is called. However, what is not clear is why these patches are so specific to x86_64.

It looks possible to do the work of functions like split_nodes_equal() in an architecture-independent manner using early_node_map rather than dealing with the arch-specific nodes array. That would open the possibility of providing fake nodes on more than one architecture in the future.

What I think can be done is that you register memory as normal and then split up the nodes into fake nodes. This would remove the need for having e820_hole_size() reintroduced.

Signed-off-by: David Rientjes <reintjes@xxxxxxxxxx>
Signed-off-by: Paul Menage <menage@xxxxxxxxxx>
Signed-off-by: Rohit Seth <rohitseth@xxxxxxxxxx>

--- linux-2.6.19-rc5-mm2.org/include/asm-x86_64/e820.h 2006-11-22 12:20:39.000000000 -0800
+++ linux-2.6.19-rc5-mm2/include/asm-x86_64/e820.h 2006-11-22 12:17:25.000000000 -0800
@@ -46,6 +46,7 @@ extern void e820_mark_nosave_regions(voi
extern void e820_print_map(char *who);
extern int e820_any_mapped(unsigned long start, unsigned long end, unsigned type);
extern int e820_all_mapped(unsigned long start, unsigned long end, unsigned type);
+extern unsigned long e820_hole_size(unsigned long start, unsigned long end);

extern void e820_setup_gap(void);
extern void e820_register_active_regions(int nid,
--- linux-2.6.19-rc5-mm2.org/arch/x86_64/kernel/e820.c 2006-11-22 12:20:55.000000000 -0800
+++ linux-2.6.19-rc5-mm2/arch/x86_64/kernel/e820.c 2006-11-21 18:48:15.000000000 -0800
@@ -184,6 +184,38 @@ unsigned long __init e820_end_of_ram(voi
}

/*
+ * Find the hole size in the range.
+ */
+unsigned long __init e820_hole_size(unsigned long start, unsigned long end)
+{
+ unsigned long ram = 0;
+ int i;
+
+ for (i = 0; i < e820.nr_map; i++) {
+ struct e820entry *ei = &e820.map[i];
+ unsigned long last, addr;
+
+ if (ei->type != E820_RAM ||
+ ei->addr+ei->size <= start ||
+ ei->addr >= end)
+ continue;
+
+ addr = round_up(ei->addr, PAGE_SIZE);
+ if (addr < start)
+ addr = start;
+
+ last = round_down(ei->addr + ei->size, PAGE_SIZE);
+ if (last >= end)
+ last = end;
+
+ if (last > addr)
+ ram += last - addr;
+ }
+ return ((end - start) - ram);
+}
+
+
+/*
* Mark e820 reserved areas as busy for the resource manager.
*/
void __init e820_reserve_resources(void)



--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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