From: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> Subject: 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@xxxxxxxxxx: v5] Link: http://lkml.kernel.org/r/20180228030308.1116-7-pasha.tatashin@xxxxxxxxxx Link: http://lkml.kernel.org/r/20180215165920.8570-7-pasha.tatashin@xxxxxxxxxx Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Baoquan He <bhe@xxxxxxxxxx> Cc: Bharata B Rao <bharata@xxxxxxxxxxxxxxxxxx> Cc: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Cc: Steven Sistare <steven.sistare@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/base/node.c | 2 ++ include/linux/memory.h | 1 + mm/memory_hotplug.c | 27 ++++++++------------------- mm/page_alloc.c | 28 ++++++++++------------------ mm/sparse.c | 8 +++++++- 5 files changed, 28 insertions(+), 38 deletions(-) diff -puN drivers/base/node.c~mm-memory_hotplug-optimize-memory-hotplug drivers/base/node.c --- a/drivers/base/node.c~mm-memory_hotplug-optimize-memory-hotplug +++ a/drivers/base/node.c @@ -407,6 +407,8 @@ int register_mem_sect_under_node(struct if (!mem_blk) return -EFAULT; + + mem_blk->nid = nid; if (!node_online(nid)) return 0; diff -puN include/linux/memory.h~mm-memory_hotplug-optimize-memory-hotplug include/linux/memory.h --- a/include/linux/memory.h~mm-memory_hotplug-optimize-memory-hotplug +++ a/include/linux/memory.h @@ -33,6 +33,7 @@ struct memory_block { void *hw; /* optional pointer to fw/hw data */ int (*phys_callback)(struct memory_block *); struct device dev; + int nid; /* NID for this memory block */ }; int arch_get_memory_phys_device(unsigned long start_pfn); diff -puN mm/memory_hotplug.c~mm-memory_hotplug-optimize-memory-hotplug mm/memory_hotplug.c --- a/mm/memory_hotplug.c~mm-memory_hotplug-optimize-memory-hotplug +++ a/mm/memory_hotplug.c @@ -250,7 +250,6 @@ static int __meminit __add_section(int n struct vmem_altmap *altmap, bool want_memblock) { int ret; - int i; if (pfn_valid(phys_start_pfn)) return -EEXIST; @@ -259,23 +258,6 @@ static int __meminit __add_section(int n if (ret < 0) return ret; - /* - * Make all the pages reserved so that nobody will stumble over half - * initialized state. - * FIXME: We also have to associate it with a node because page_to_nid - * relies on having page with the proper node. - */ - for (i = 0; i < PAGES_PER_SECTION; i++) { - unsigned long pfn = phys_start_pfn + i; - struct page *page; - if (!pfn_valid(pfn)) - continue; - - page = pfn_to_page(pfn); - set_page_node(page, nid); - SetPageReserved(page); - } - if (!want_memblock) return 0; @@ -908,8 +890,15 @@ int __ref online_pages(unsigned long pfn int nid; int ret; struct memory_notify arg; + struct memory_block *mem; + + /* + * We can't use pfn_to_nid() because nid might be stored in struct page + * which is not yet initialized. Instead, we find nid from memory block. + */ + mem = find_memory_block(__pfn_to_section(pfn)); + nid = mem->nid; - nid = pfn_to_nid(pfn); /* associate pfn range with the zone */ zone = move_pfn_range(online_type, nid, pfn, nr_pages); diff -puN mm/page_alloc.c~mm-memory_hotplug-optimize-memory-hotplug mm/page_alloc.c --- a/mm/page_alloc.c~mm-memory_hotplug-optimize-memory-hotplug +++ a/mm/page_alloc.c @@ -1143,10 +1143,9 @@ static void free_one_page(struct zone *z } static void __meminit __init_single_page(struct page *page, unsigned long pfn, - unsigned long zone, int nid, bool zero) + unsigned long zone, int nid) { - if (zero) - mm_zero_struct_page(page); + mm_zero_struct_page(page); set_page_links(page, zone, nid, pfn); init_page_count(page); page_mapcount_reset(page); @@ -1160,12 +1159,6 @@ static void __meminit __init_single_page #endif } -static void __meminit __init_single_pfn(unsigned long pfn, unsigned long zone, - int nid, bool zero) -{ - return __init_single_page(pfn_to_page(pfn), pfn, zone, nid, zero); -} - #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT static void __meminit init_reserved_page(unsigned long pfn) { @@ -1184,7 +1177,7 @@ static void __meminit init_reserved_page if (pfn >= zone->zone_start_pfn && pfn < zone_end_pfn(zone)) break; } - __init_single_pfn(pfn, zid, nid, true); + __init_single_page(pfn_to_page(pfn), pfn, zid, nid); } #else static inline void init_reserved_page(unsigned long pfn) @@ -1501,7 +1494,7 @@ static unsigned long __init deferred_in } else { page++; } - __init_single_page(page, pfn, zid, nid, true); + __init_single_page(page, pfn, zid, nid); nr_pages++; } return (nr_pages); @@ -5434,6 +5427,7 @@ void __meminit memmap_init_zone(unsigned pg_data_t *pgdat = NODE_DATA(nid); unsigned long pfn; unsigned long nr_initialised = 0; + struct page *page; #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP struct memblock_region *r = NULL, *tmp; #endif @@ -5486,6 +5480,11 @@ void __meminit memmap_init_zone(unsigned #endif not_early: + page = pfn_to_page(pfn); + __init_single_page(page, pfn, zone, nid); + if (context == MEMMAP_HOTPLUG) + SetPageReserved(page); + /* * Mark the block movable so that blocks are reserved for * movable at startup. This will force kernel allocations @@ -5502,15 +5501,8 @@ not_early: * because this is done early in sparse_add_one_section */ if (!(pfn & (pageblock_nr_pages - 1))) { - struct page *page = pfn_to_page(pfn); - - __init_single_page(page, pfn, zone, nid, - context != MEMMAP_HOTPLUG); set_pageblock_migratetype(page, MIGRATE_MOVABLE); cond_resched(); - } else { - __init_single_pfn(pfn, zone, nid, - context != MEMMAP_HOTPLUG); } } } diff -puN mm/sparse.c~mm-memory_hotplug-optimize-memory-hotplug mm/sparse.c --- a/mm/sparse.c~mm-memory_hotplug-optimize-memory-hotplug +++ a/mm/sparse.c @@ -779,7 +779,13 @@ int __meminit sparse_add_one_section(str 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); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
