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authorPavel Tatashin <pasha.tatashin@oracle.com>2018-08-17 15:44:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-17 16:20:28 -0700
commit720e14ebec642bc56c44e5e60a2d595900e5bbf0 (patch)
tree0cf640d04be919592ed18fc197491732f7e630fd /mm/page_alloc.c
parent50a7ca3c6fc86955f99fc432fc8a186b968b365b (diff)
mm: skip invalid pages block at a time in zero_resv_unresv()
The role of zero_resv_unavail() is to make sure that every struct page that is allocated but is not backed by memory that is accessible by kernel is zeroed and not in some uninitialized state. Since struct pages are allocated in blocks (2M pages in x86 case), we can skip pageblock_nr_pages at a time, when the first one is found to be invalid. This optimization may help since now on x86 every hole in e820 maps is marked as reserved in memblock, and thus will go through this function. This function is called before sched_clock() is initialized, so I used my x86 early boot clock patches to measure the performance improvement. With 1T hole on i7-8700 currently we would take 0.606918s of boot time, but with this optimization 0.001103s. Link: http://lkml.kernel.org/r/20180615155733.1175-1-pasha.tatashin@oracle.com Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com> Cc: Steven Sistare <steven.sistare@oracle.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0922ef5d2e46..33f6745bb649 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6405,8 +6405,11 @@ void __paginginit zero_resv_unavail(void)
pgcnt = 0;
for_each_resv_unavail_range(i, &start, &end) {
for (pfn = PFN_DOWN(start); pfn < PFN_UP(end); pfn++) {
- if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages)))
+ if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) {
+ pfn = ALIGN_DOWN(pfn, pageblock_nr_pages)
+ + pageblock_nr_pages - 1;
continue;
+ }
mm_zero_struct_page(pfn_to_page(pfn));
pgcnt++;
}