From 485761bd6a72d33b3d4fa884927b2b0d983b701e Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Fri, 26 Aug 2005 18:34:10 -0700 Subject: [PATCH] x86_64: Tell VM about holes in nodes Some nodes can have large holes on x86-64. This fixes problems with the VM allowing too many dirty pages because it overestimates the number of available RAM in a node. In extreme cases you can end up with all RAM filled with dirty pages which can lead to deadlocks and other nasty behaviour. This patch just tells the VM about the known holes from e820. Reserved (like the kernel text or mem_map) is still not taken into account, but that should be only a few percent error now. Small detail is that the flat setup uses the NUMA free_area_init_node() now too because it offers more flexibility. (akpm: lotsa thanks to Martin for working this problem out) Cc: Martin Bligh Signed-off-by: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86_64/kernel/e820.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) (limited to 'arch/x86_64/kernel/e820.c') diff --git a/arch/x86_64/kernel/e820.c b/arch/x86_64/kernel/e820.c index 6ded3a5..b548dea 100644 --- a/arch/x86_64/kernel/e820.c +++ b/arch/x86_64/kernel/e820.c @@ -185,6 +185,40 @@ unsigned long __init e820_end_of_ram(void) } /* + * Compute how much memory is missing in a range. + * Unlike the other functions in this file the arguments are in page numbers. + */ +unsigned long __init +e820_hole_size(unsigned long start_pfn, unsigned long end_pfn) +{ + unsigned long ram = 0; + unsigned long start = start_pfn << PAGE_SHIFT; + unsigned long end = end_pfn << PAGE_SHIFT; + 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) >> PAGE_SHIFT; +} + +/* * Mark e820 reserved areas as busy for the resource manager. */ void __init e820_reserve_resources(void) -- cgit v1.1