The patch titled
Subject: mm: return zero_resv_unavail optimization
has been added to the -mm tree. Its filename is
mm-return-zero_resv_unavail-optimization.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-return-zero_resv_unavail-optimization.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-return-zero_resv_unavail-optimization.patch
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------------------------------------------------------
From: Pavel Tatashin <pavel.tatashin@xxxxxxxxxxxxx>
Subject: mm: return zero_resv_unavail optimization
When checking for valid pfns in zero_resv_unavail(), it is not necessary
to verify that pfns within pageblock_nr_pages ranges are valid, only the
first one needs to be checked. This is because memory for pages are
allocated in contiguous chunks that contain pageblock_nr_pages struct
pages.
Link: http://lkml.kernel.org/r/20181002143821.5112-3-msys.mizuma@xxxxxxxxx
Signed-off-by: Pavel Tatashin <pavel.tatashin@xxxxxxxxxxxxx>
Signed-off-by: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>
Reviewed-by: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>
Acked-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN mm/page_alloc.c~mm-return-zero_resv_unavail-optimization mm/page_alloc.c
--- a/mm/page_alloc.c~mm-return-zero_resv_unavail-optimization
+++ a/mm/page_alloc.c
@@ -6517,6 +6517,29 @@ void __init free_area_init_node(int nid,
}
#if defined(CONFIG_HAVE_MEMBLOCK) && !defined(CONFIG_FLAT_NODE_MEM_MAP)
+
+/*
+ * Zero all valid struct pages in range [spfn, epfn), return number of struct
+ * pages zeroed
+ */
+static u64 zero_pfn_range(unsigned long spfn, unsigned long epfn)
+{
+ unsigned long pfn;
+ u64 pgcnt = 0;
+
+ for (pfn = spfn; pfn < epfn; pfn++) {
+ 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++;
+ }
+
+ return pgcnt;
+}
+
/*
* Only struct pages that are backed by physical memory are zeroed and
* initialized by going through __init_single_page(). But, there are some
@@ -6532,7 +6555,6 @@ void __init free_area_init_node(int nid,
void __init zero_resv_unavail(void)
{
phys_addr_t start, end;
- unsigned long pfn;
u64 i, pgcnt;
phys_addr_t next = 0;
@@ -6542,34 +6564,18 @@ void __init zero_resv_unavail(void)
pgcnt = 0;
for_each_mem_range(i, &memblock.memory, NULL,
NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end, NULL) {
- if (next < start) {
- for (pfn = PFN_DOWN(next); pfn < PFN_UP(start); pfn++) {
- if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages)))
- continue;
- mm_zero_struct_page(pfn_to_page(pfn));
- pgcnt++;
- }
- }
+ if (next < start)
+ pgcnt += zero_pfn_range(PFN_DOWN(next), PFN_UP(start));
next = end;
}
- for (pfn = PFN_DOWN(next); pfn < max_pfn; pfn++) {
- if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages)))
- continue;
- mm_zero_struct_page(pfn_to_page(pfn));
- pgcnt++;
- }
-
+ pgcnt += zero_pfn_range(PFN_DOWN(next), max_pfn);
/*
* Struct pages that do not have backing memory. This could be because
* firmware is using some of this memory, or for some other reasons.
- * Once memblock is changed so such behaviour is not allowed: i.e.
- * list of "reserved" memory must be a subset of list of "memory", then
- * this code can be removed.
*/
if (pgcnt)
pr_info("Zeroed struct page in unavailable ranges: %lld pages", pgcnt);
-
}
#endif /* CONFIG_HAVE_MEMBLOCK && !CONFIG_FLAT_NODE_MEM_MAP */
_
Patches currently in -mm which might be from pavel.tatashin@xxxxxxxxxxxxx are
mm-return-zero_resv_unavail-optimization.patch
