On Wed, Oct 03, 2012 at 08:56:14AM -0600, Mike Yoknis wrote: > 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 sections to reduce the > number of loops executed. > > Signed-off-by: Mike Yoknis <mike.yoknis@xxxxxx> This only helps SPARSEMEM and changes more headers than should be necessary. It would have been easier to do something simple like if (!early_pfn_valid(pfn)) { pfn = ALIGN(pfn + MAX_ORDER_NR_PAGES, MAX_ORDER_NR_PAGES) - 1; continue; } because that would obey the expectation that pages within a MAX_ORDER_NR_PAGES-aligned range are all valid or all invalid (ARM is the exception that breaks this rule). It would be less efficient on SPARSEMEM than what you're trying to merge but I do not see the need for the additional complexity unless you can show it makes a big difference to boot times. -- Mel Gorman SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html