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authorPavel Tatashin <pasha.tatashin@oracle.com>2018-04-05 16:23:00 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-05 21:36:25 -0700
commitd0dc12e86b3197a14a908d4fe7cb35b73dda82b5 (patch)
tree28bd3b5c716e3e1c04fab511c3a41033bdc85993 /mm/sparse.c
parentfc44f7f9231a73821fc858f5bc48883a9e78f6de (diff)
mm/memory_hotplug: optimize memory hotplug
During memory hotplugging we traverse struct pages three times: 1. memset(0) in sparse_add_one_section() 2. loop in __add_section() to set do: set_page_node(page, nid); and SetPageReserved(page); 3. loop in memmap_init_zone() to call __init_single_pfn() This patch removes the first two loops, and leaves only loop 3. All struct pages are initialized in one place, the same as it is done during boot. The benefits: - We improve memory hotplug performance because we are not evicting the cache several times and also reduce loop branching overhead. - Remove condition from hotpath in __init_single_pfn(), that was added in order to fix the problem that was reported by Bharata in the above email thread, thus also improve performance during normal boot. - Make memory hotplug more similar to the boot memory initialization path because we zero and initialize struct pages only in one function. - Simplifies memory hotplug struct page initialization code, and thus enables future improvements, such as multi-threading the initialization of struct pages in order to improve hotplug performance even further on larger machines. [pasha.tatashin@oracle.com: v5] Link: http://lkml.kernel.org/r/20180228030308.1116-7-pasha.tatashin@oracle.com Link: http://lkml.kernel.org/r/20180215165920.8570-7-pasha.tatashin@oracle.com Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com> Reviewed-by: Ingo Molnar <mingo@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Baoquan He <bhe@redhat.com> Cc: Bharata B Rao <bharata@linux.vnet.ibm.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Steven Sistare <steven.sistare@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/sparse.c')
-rw-r--r--mm/sparse.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/mm/sparse.c b/mm/sparse.c
index 58cab483e81b..62eef264a7bd 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -779,7 +779,13 @@ int __meminit sparse_add_one_section(struct pglist_data *pgdat,
goto out;
}
- memset(memmap, 0, sizeof(struct page) * PAGES_PER_SECTION);
+#ifdef CONFIG_DEBUG_VM
+ /*
+ * Poison uninitialized struct pages in order to catch invalid flags
+ * combinations.
+ */
+ memset(memmap, PAGE_POISON_PATTERN, sizeof(struct page) * PAGES_PER_SECTION);
+#endif
section_mark_present(ms);