When freeing pages are done with higher order, time spent on coalescing pages by buddy allocator can be reduced. With section size of 256MB, hot add latency of a single section shows improvement from 50-60 ms to less than 1 ms, hence improving the hot add latency by 60 times. Modify external providers of online callback to align with the change. Signed-off-by: Arun KS <arunks@xxxxxxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Reviewed-by: Oscar Salvador <osalvador@xxxxxxx> --- Changes since v8: - Remove return type change for online_page_callback. - Use consistent names for external online_page providers. - Fix onlined_pages accounting. Changes since v7: - Rebased to 5.0-rc1. - Fixed onlined_pages accounting. - Added comment for return value of online_page_callback. - Renamed xen_bring_pgs_online to xen_online_pages. Changes since v6: - Rebased to 4.20 - Changelog updated. - No improvement seen on arm64, hence removed removal of prefetch. Changes since v5: - Rebased to 4.20-rc1. - Changelog updated. Changes since v4: - As suggested by Michal Hocko, - Simplify logic in online_pages_block() by using get_order(). - Seperate out removal of prefetch from __free_pages_core(). Changes since v3: - Renamed _free_pages_boot_core -> __free_pages_core. - Removed prefetch from __free_pages_core. - Removed xen_online_page(). Changes since v2: - Reuse code from __free_pages_boot_core(). Changes since v1: - Removed prefetch(). Changes since RFC: - Rebase. - As suggested by Michal Hocko remove pages_per_block. - Modifed external providers of online_page_callback. v8: https://lore.kernel.org/patchwork/patch/1030332/ v7: https://lore.kernel.org/patchwork/patch/1028908/ v6: https://lore.kernel.org/patchwork/patch/1007253/ v5: https://lore.kernel.org/patchwork/patch/995739/ v4: https://lore.kernel.org/patchwork/patch/995111/ v3: https://lore.kernel.org/patchwork/patch/992348/ v2: https://lore.kernel.org/patchwork/patch/991363/ v1: https://lore.kernel.org/patchwork/patch/989445/ RFC: https://lore.kernel.org/patchwork/patch/984754/ --- --- drivers/hv/hv_balloon.c | 4 ++-- drivers/xen/balloon.c | 15 ++++++++++----- include/linux/memory_hotplug.h | 2 +- mm/internal.h | 1 + mm/memory_hotplug.c | 37 +++++++++++++++++++++++++------------ mm/page_alloc.c | 8 ++++---- 6 files changed, 43 insertions(+), 24 deletions(-) diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c index 5301fef..55d79f8 100644 --- a/drivers/hv/hv_balloon.c +++ b/drivers/hv/hv_balloon.c @@ -771,7 +771,7 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size, } } -static void hv_online_page(struct page *pg) +static void hv_online_page(struct page *pg, unsigned int order) { struct hv_hotadd_state *has; unsigned long flags; @@ -783,7 +783,7 @@ static void hv_online_page(struct page *pg) if ((pfn < has->start_pfn) || (pfn >= has->end_pfn)) continue; - hv_page_online_one(has, pg); + hv_bring_pgs_online(has, pfn, (1UL << order)); break; } spin_unlock_irqrestore(&dm_device.ha_lock, flags); diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index ceb5048..d107447 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -369,14 +369,19 @@ static enum bp_state reserve_additional_memory(void) return BP_ECANCELED; } -static void xen_online_page(struct page *page) +static void xen_online_page(struct page *page, unsigned int order) { - __online_page_set_limits(page); + unsigned long i, size = (1 << order); + unsigned long start_pfn = page_to_pfn(page); + struct page *p; + pr_debug("Online %lu pages starting at pfn 0x%lx\n", size, start_pfn); mutex_lock(&balloon_mutex); - - __balloon_append(page); - + for (i = 0; i < size; i++) { + p = pfn_to_page(start_pfn + i); + __online_page_set_limits(p); + __balloon_append(p); + } mutex_unlock(&balloon_mutex); } diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index 07da5c6..e368730 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -87,7 +87,7 @@ extern int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn, unsigned long *valid_start, unsigned long *valid_end); extern void __offline_isolated_pages(unsigned long, unsigned long); -typedef void (*online_page_callback_t)(struct page *page); +typedef void (*online_page_callback_t)(struct page *page, unsigned int order); extern int set_online_page_callback(online_page_callback_t callback); extern int restore_online_page_callback(online_page_callback_t callback); diff --git a/mm/internal.h b/mm/internal.h index f4a7bb0..536bc2a 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -163,6 +163,7 @@ static inline struct page *pageblock_pfn_to_page(unsigned long start_pfn, extern int __isolate_free_page(struct page *page, unsigned int order); extern void memblock_free_pages(struct page *page, unsigned long pfn, unsigned int order); +extern void __free_pages_core(struct page *page, unsigned int order); extern void prep_compound_page(struct page *page, unsigned int order); extern void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags); diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index b9a667d..77dff24 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -47,7 +47,7 @@ * and restore_online_page_callback() for generic callback restore. */ -static void generic_online_page(struct page *page); +static void generic_online_page(struct page *page, unsigned int order); static online_page_callback_t online_page_callback = generic_online_page; static DEFINE_MUTEX(online_page_callback_lock); @@ -656,26 +656,39 @@ void __online_page_free(struct page *page) } EXPORT_SYMBOL_GPL(__online_page_free); -static void generic_online_page(struct page *page) +static void generic_online_page(struct page *page, unsigned int order) { - __online_page_set_limits(page); - __online_page_increment_counters(page); - __online_page_free(page); + __free_pages_core(page, order); + totalram_pages_add(1UL << order); +#ifdef CONFIG_HIGHMEM + if (PageHighMem(page)) + totalhigh_pages_add(1UL << order); +#endif +} + +static int online_pages_blocks(unsigned long start, unsigned long nr_pages) +{ + unsigned long end = start + nr_pages; + int order, ret, onlined_pages = 0; + + while (start < end) { + order = min(MAX_ORDER - 1, + get_order(PFN_PHYS(end) - PFN_PHYS(start))); + (*online_page_callback)(pfn_to_page(start), order); + + onlined_pages += (1UL << order); + start += (1UL << order); + } + return onlined_pages; } static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages, void *arg) { - unsigned long i; unsigned long onlined_pages = *(unsigned long *)arg; - struct page *page; if (PageReserved(pfn_to_page(start_pfn))) - for (i = 0; i < nr_pages; i++) { - page = pfn_to_page(start_pfn + i); - (*online_page_callback)(page); - onlined_pages++; - } + onlined_pages += online_pages_blocks(start_pfn, nr_pages); online_mem_sections(start_pfn, start_pfn + nr_pages); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d295c9b..883212a 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1303,7 +1303,7 @@ static void __free_pages_ok(struct page *page, unsigned int order) local_irq_restore(flags); } -static void __init __free_pages_boot_core(struct page *page, unsigned int order) +void __free_pages_core(struct page *page, unsigned int order) { unsigned int nr_pages = 1 << order; struct page *p = page; @@ -1382,7 +1382,7 @@ void __init memblock_free_pages(struct page *page, unsigned long pfn, { if (early_page_uninitialised(pfn)) return; - return __free_pages_boot_core(page, order); + __free_pages_core(page, order); } /* @@ -1472,14 +1472,14 @@ static void __init deferred_free_range(unsigned long pfn, if (nr_pages == pageblock_nr_pages && (pfn & (pageblock_nr_pages - 1)) == 0) { set_pageblock_migratetype(page, MIGRATE_MOVABLE); - __free_pages_boot_core(page, pageblock_order); + __free_pages_core(page, pageblock_order); return; } for (i = 0; i < nr_pages; i++, page++, pfn++) { if ((pfn & (pageblock_nr_pages - 1)) == 0) set_pageblock_migratetype(page, MIGRATE_MOVABLE); - __free_pages_boot_core(page, 0); + __free_pages_core(page, 0); } } -- 1.9.1
