Commit 309d0b39 authored Nov 12, 2013 by Robin Holt Committed by Linus Torvalds Nov 13, 2013

mm/nobootmem.c: have __free_pages_memory() free in larger chunks.



On large memory machines it can take a few minutes to get through
free_all_bootmem().

Currently, when free_all_bootmem() calls __free_pages_memory(), the number
of contiguous pages that __free_pages_memory() passes to the buddy
allocator is limited to BITS_PER_LONG.  BITS_PER_LONG was originally
chosen to keep things similar to mm/nobootmem.c.  But it is more efficient
to limit it to MAX_ORDER.

       base   new  change
8TB    202s  172s   30s
16TB   401s  351s   50s

That is around 1%-3% improvement on total boot time.

This patch was spun off from the boot time rfc Robin and I had been
working on.

Signed-off-by: Robin Holt <robin.m.holt@gmail.com>
Signed-off-by: Nathan Zimmer <nzimmer@sgi.com>
Cc: Robin Holt <robinmholt@linux.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mike Travis <travis@sgi.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent b9921ecd

mm/nobootmem.c

+8 −17

Original line number	Diff line number	Diff line
		@@ -82,27 +82,18 @@ void __init free_bootmem_late(unsigned long addr, unsigned long size)

		static void __init __free_pages_memory(unsigned long start, unsigned long end)
		{
		unsigned long i, start_aligned, end_aligned;
		int order = ilog2(BITS_PER_LONG);
		int order;

		start_aligned = (start + (BITS_PER_LONG - 1)) & ~(BITS_PER_LONG - 1);
		end_aligned = end & ~(BITS_PER_LONG - 1);
		while (start < end) {
		order = min(MAX_ORDER - 1UL, __ffs(start));

		if (end_aligned <= start_aligned) {
		for (i = start; i < end; i++)
		__free_pages_bootmem(pfn_to_page(i), 0);
		while (start + (1UL << order) > end)
		order--;

		return;
		}

		for (i = start; i < start_aligned; i++)
		__free_pages_bootmem(pfn_to_page(i), 0);
		__free_pages_bootmem(pfn_to_page(start), order);

		for (i = start_aligned; i < end_aligned; i += BITS_PER_LONG)
		__free_pages_bootmem(pfn_to_page(i), order);

		for (i = end_aligned; i < end; i++)
		__free_pages_bootmem(pfn_to_page(i), 0);
		start += (1UL << order);
		}
		}

		static unsigned long __init __free_memory_core(phys_addr_t start,

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