Messages in this thread Patch in this message | | | From | Nathan Zimmer <> | Subject | [PATCH] Have __free_pages_memory() free in larger chunks. | Date | Tue, 10 Sep 2013 13:57:24 -0500 |
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From: Robin Holt <robin.m.holt@gmail.com>
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> To: "H. Peter Anvin" <hpa@zytor.com> To: Ingo Molnar <mingo@kernel.org> Cc: Linux Kernel <linux-kernel@vger.kernel.org> Cc: Linux MM <linux-mm@kvack.org> Cc: Rob Landley <rob@landley.net> Cc: Mike Travis <travis@sgi.com> Cc: Daniel J Blueman <daniel@numascale-asia.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Mel Gorman <mgorman@suse.de> --- mm/nobootmem.c | 25 ++++++++----------------- 1 file changed, 8 insertions(+), 17 deletions(-)
diff --git a/mm/nobootmem.c b/mm/nobootmem.c index 61107cf..2c254d3 100644 --- a/mm/nobootmem.c +++ b/mm/nobootmem.c @@ -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, -- 1.8.2.1
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