On Fri, 2019-01-04 at 10:31 +0530, Arun KS wrote: > 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 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. > > 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 | 6 ++++-- > drivers/xen/balloon.c | 23 +++++++++++++++-------- > include/linux/memory_hotplug.h | 2 +- > mm/internal.h | 1 + > mm/memory_hotplug.c | 42 ++++++++++++++++++++++++++++++------------ > mm/page_alloc.c | 8 ++++---- > 6 files changed, 55 insertions(+), 27 deletions(-) > > diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c > index 5301fef..211f3fe 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 int hv_online_page(struct page *pg, unsigned int order) > { > struct hv_hotadd_state *has; > unsigned long flags; > @@ -783,10 +783,12 @@ 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); > + > + return 0; > } > > static int pfn_covered(unsigned long start_pfn, unsigned long pfn_cnt) > diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c > index ceb5048..95f888f 100644 > --- a/drivers/xen/balloon.c > +++ b/drivers/xen/balloon.c > @@ -345,8 +345,8 @@ static enum bp_state reserve_additional_memory(void) > > /* > * add_memory_resource() will call online_pages() which in its turn > - * will call xen_online_page() callback causing deadlock if we don't > - * release balloon_mutex here. Unlocking here is safe because the > + * will call xen_bring_pgs_online() callback causing deadlock if we > + * don't release balloon_mutex here. Unlocking here is safe because the > * callers drop the mutex before trying again. > */ > mutex_unlock(&balloon_mutex); > @@ -369,15 +369,22 @@ static enum bp_state reserve_additional_memory(void) > return BP_ECANCELED; > } > > -static void xen_online_page(struct page *page) > +static int xen_bring_pgs_online(struct page *pg, unsigned int order) > { > - __online_page_set_limits(page); > + unsigned long i, size = (1 << order); > + unsigned long start_pfn = page_to_pfn(pg); > + 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); > + > + return 0; > } > > static int xen_memory_notifier(struct notifier_block *nb, unsigned long val, void *v) > @@ -702,7 +709,7 @@ static int __init balloon_init(void) > balloon_stats.max_retry_count = RETRY_UNLIMITED; > > #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG > - set_online_page_callback(&xen_online_page); > + set_online_page_callback(&xen_bring_pgs_online); > register_memory_notifier(&xen_memory_nb); > register_sysctl_table(xen_root); > #endif > diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h > index 07da5c6..d56bfba 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 int (*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..0ea0eb1 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 int 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 +656,44 @@ void __online_page_free(struct page *page) > } > EXPORT_SYMBOL_GPL(__online_page_free); > > -static void generic_online_page(struct page *page) > +static int 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 > + return 0; > +} > + > +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))); > + > + ret = (*online_page_callback)(pfn_to_page(start), order); > + if (!ret) > + onlined_pages += (1UL << order); > + else if (ret > 0) > + onlined_pages += ret; > + > + 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); Shouldn't this be a "+=" instead of an "="? It seems like you are going to lose your count otherwise. > > online_mem_sections(start_pfn, start_pfn + nr_pages); > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index cde5dac..f51a920 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); > } > } >
