Subject: [-] mm-memmap_init_zone-performance-improvement.patch removed from -mm tree To: mike.yoknis@xxxxxx,hannes@xxxxxxxxxxx,mgorman@xxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Wed, 10 Jul 2013 13:25:01 -0700 The patch titled Subject: mm: memmap_init_zone() performance improvement has been removed from the -mm tree. Its filename was mm-memmap_init_zone-performance-improvement.patch This patch was dropped because it has gone stale ------------------------------------------------------ From: Mike Yoknis <mike.yoknis@xxxxxx> Subject: mm: memmap_init_zone() performance improvement We have what we call an "architectural simulator". It is a computer program that pretends that it is a computer system. We use it to test the firmware before real hardware is available. We have booted Linux on our simulator. As you would expect it takes longer to boot on the simulator than it does on real hardware. With my patch - boot time 41 minutes Without patch - boot time 94 minutes These numbers do not scale linearly to real hardware. But indicate to me a place where Linux can be improved. memmap_init_zone() loops through every Page Frame Number (pfn), including pfn values that are within the gaps between existing memory sections. The unneeded looping will become a boot performance issue when machines configure larger memory ranges that will contain larger and more numerous gaps. The code will skip across invalid pfn values to reduce the number of loops executed. Signed-off-by: Mike Yoknis <mike.yoknis@xxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/page_alloc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff -puN mm/page_alloc.c~mm-memmap_init_zone-performance-improvement mm/page_alloc.c --- a/mm/page_alloc.c~mm-memmap_init_zone-performance-improvement +++ a/mm/page_alloc.c @@ -3933,8 +3933,11 @@ void __meminit memmap_init_zone(unsigned * exist on hotplugged memory. */ if (context == MEMMAP_EARLY) { - if (!early_pfn_valid(pfn)) + if (!early_pfn_valid(pfn)) { + pfn = ALIGN(pfn + MAX_ORDER_NR_PAGES, + MAX_ORDER_NR_PAGES) - 1; continue; + } if (!early_pfn_in_nid(pfn, nid)) continue; } _ Patches currently in -mm which might be from mike.yoknis@xxxxxx are -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html