On 4/5/2018 7:34 PM, Matthew Wilcox Wrote:
On Thu, Apr 05, 2018 at 01:04:35AM -0700, Jia He wrote:Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns where possible") optimized the loop in memmap_init_zone(). But there is still some room for improvement. E.g. if pfn and pfn+1 are in the same memblock region, we can simply pfn++ instead of doing the binary search in memblock_next_valid_pfn.Sure, but I bet if we are >end_pfn, we're almost certainly going to the start_pfn of the next block, so why not test that as well?+ /* fast path, return pfn+1 if next pfn is in the same region */ + if (early_region_idx != -1) { + start_pfn = PFN_DOWN(regions[early_region_idx].base); + end_pfn = PFN_DOWN(regions[early_region_idx].base + + regions[early_region_idx].size); + + if (pfn >= start_pfn && pfn < end_pfn) + return pfn;early_region_idx++; start_pfn = PFN_DOWN(regions[early_region_idx].base); if (pfn >= end_pfn && pfn <= start_pfn) return start_pfn;
Thanks, thus the binary search in next step can be discarded? -- Cheers, Jia
