Re: [PATCH] memory_hotplug: Free pages as higher order
On 2018-09-21 21:12, Dan Williams wrote: On Fri, Sep 21, 2018 at 2:40 AM Arun KS wrote: When free pages are done with higher order, time spend 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%. Modify external providers of online callback to align with the change. Signed-off-by: Arun KS --- Changes since RFC: - Rebase. - As suggested by Michal Hocko remove pages_per_block. - Modifed external providers of online_page_callback. RFC: https://lore.kernel.org/patchwork/patch/984754/ --- drivers/hv/hv_balloon.c| 6 +++-- drivers/xen/balloon.c | 18 +++--- include/linux/memory_hotplug.h | 2 +- mm/memory_hotplug.c| 55 +- 4 files changed, 63 insertions(+), 18 deletions(-) diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c index b1b7880..c5bc0b5 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(_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 e12bb25..010cf4d 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -390,8 +390,8 @@ 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(_mutex); @@ -422,6 +422,18 @@ static void xen_online_page(struct page *page) mutex_unlock(_mutex); } +static int xen_bring_pgs_online(struct page *pg, unsigned int order) +{ + unsigned long i, size = (1 << order); + unsigned long start_pfn = page_to_pfn(pg); + + pr_debug("Online %lu pages starting at pfn 0x%lx\n", size, start_pfn); + for (i = 0; i < size; i++) + xen_online_page(pfn_to_page(start_pfn + i)); + + return 0; +} + static int xen_memory_notifier(struct notifier_block *nb, unsigned long val, void *v) { if (val == MEM_ONLINE) @@ -744,7 +756,7 @@ static int __init balloon_init(void) balloon_stats.max_retry_count = RETRY_UNLIMITED; #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG - set_online_page_callback(_online_page); + set_online_page_callback(_bring_pgs_online); register_memory_notifier(_memory_nb); register_sysctl_table(xen_root); diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index 34a2822..7b04c1d 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/memory_hotplug.c b/mm/memory_hotplug.c index 38d94b7..24c2b8e 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); @@ -655,26 +655,57 @@ 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); -
Re: [PATCH] memory_hotplug: Free pages as higher order
On 2018-09-21 21:12, Dan Williams wrote: On Fri, Sep 21, 2018 at 2:40 AM Arun KS wrote: When free pages are done with higher order, time spend 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%. Modify external providers of online callback to align with the change. Signed-off-by: Arun KS --- Changes since RFC: - Rebase. - As suggested by Michal Hocko remove pages_per_block. - Modifed external providers of online_page_callback. RFC: https://lore.kernel.org/patchwork/patch/984754/ --- drivers/hv/hv_balloon.c| 6 +++-- drivers/xen/balloon.c | 18 +++--- include/linux/memory_hotplug.h | 2 +- mm/memory_hotplug.c| 55 +- 4 files changed, 63 insertions(+), 18 deletions(-) diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c index b1b7880..c5bc0b5 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(_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 e12bb25..010cf4d 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -390,8 +390,8 @@ 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(_mutex); @@ -422,6 +422,18 @@ static void xen_online_page(struct page *page) mutex_unlock(_mutex); } +static int xen_bring_pgs_online(struct page *pg, unsigned int order) +{ + unsigned long i, size = (1 << order); + unsigned long start_pfn = page_to_pfn(pg); + + pr_debug("Online %lu pages starting at pfn 0x%lx\n", size, start_pfn); + for (i = 0; i < size; i++) + xen_online_page(pfn_to_page(start_pfn + i)); + + return 0; +} + static int xen_memory_notifier(struct notifier_block *nb, unsigned long val, void *v) { if (val == MEM_ONLINE) @@ -744,7 +756,7 @@ static int __init balloon_init(void) balloon_stats.max_retry_count = RETRY_UNLIMITED; #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG - set_online_page_callback(_online_page); + set_online_page_callback(_bring_pgs_online); register_memory_notifier(_memory_nb); register_sysctl_table(xen_root); diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index 34a2822..7b04c1d 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/memory_hotplug.c b/mm/memory_hotplug.c index 38d94b7..24c2b8e 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); @@ -655,26 +655,57 @@ 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); -