From: Robin Holt <robin.m.holt@xxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: Nathan Zimmer <nzimmer@xxxxxxx>
To: "H. Peter Anvin" <hpa@xxxxxxxxx>
To: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Linux Kernel <linux-kernel@xxxxxxxxxxxxxxx>
Cc: Linux MM <linux-mm@xxxxxxxxx>
Cc: Rob Landley <rob@xxxxxxxxxxx>
Cc: Mike Travis <travis@xxxxxxx>
Cc: Daniel J Blueman <daniel@xxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
---
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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