Memory hotplug support for Xen balloon driver. It should be mentioned that hotplugged memory is not onlined automatically. It should be onlined by user through standard sysfs interface. There are a few prerequisite patches which fixes some problems found during work on memory hotplug patch or add some futures which are needed by this patch. They are available here: - https://lkml.org/lkml/2011/3/28/94, - https://lkml.org/lkml/2011/3/28/98. I have received notice that previous series of patches broke machine migration under Xen. I am going to confirm that and solve that problem ASAP. I do not have received any notices about other problems till now. Signed-off-by: Daniel Kiper <dkiper@xxxxxxxxxxxx> --- drivers/xen/Kconfig | 10 +++ drivers/xen/balloon.c | 148 ++++++++++++++++++++++++++++++++++++++++++++++++- include/xen/balloon.h | 4 + 3 files changed, 160 insertions(+), 2 deletions(-) diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig index e5ecae6..39df71b 100644 --- a/drivers/xen/Kconfig +++ b/drivers/xen/Kconfig @@ -9,6 +9,16 @@ config XEN_BALLOON the system to expand the domain's memory allocation, or alternatively return unneeded memory to the system. +config XEN_BALLOON_MEMORY_HOTPLUG + bool "Memory hotplug support for Xen balloon driver" + default n + depends on XEN_BALLOON && MEMORY_HOTPLUG + help + Memory hotplug support for Xen balloon driver allows expanding memory + available for the system above limit declared at system startup. + It is very useful on critical systems which require long + run without rebooting. + config XEN_SCRUB_PAGES bool "Scrub pages before returning them to system" depends on XEN_BALLOON diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index f54290b..189023e 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -4,6 +4,12 @@ * Copyright (c) 2003, B Dragovic * Copyright (c) 2003-2004, M Williamson, K Fraser * Copyright (c) 2005 Dan M. Smith, IBM Corporation + * Copyright (c) 2010 Daniel Kiper + * + * Memory hotplug support was written by Daniel Kiper. Work on + * it was sponsored by Google under Google Summer of Code 2010 + * program. Jeremy Fitzhardinge from Xen.org was the mentor for + * this project. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License version 2 @@ -40,6 +46,9 @@ #include <linux/mutex.h> #include <linux/list.h> #include <linux/gfp.h> +#include <linux/notifier.h> +#include <linux/memory.h> +#include <linux/memory_hotplug.h> #include <asm/page.h> #include <asm/pgalloc.h> @@ -194,6 +203,96 @@ static enum bp_state update_schedule(enum bp_state state) return BP_EAGAIN; } +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG +static long current_credit(void) +{ + return balloon_stats.target_pages - balloon_stats.current_pages - + balloon_stats.hotplug_pages; +} + +static bool balloon_is_inflated(void) +{ + if (balloon_stats.balloon_low || balloon_stats.balloon_high || + balloon_stats.balloon_hotplug) + return true; + else + return false; +} + +/* + * reserve_additional_memory() adds memory region of size >= credit above + * max_pfn. New region is section aligned and size is modified to be multiple + * of section size. Those features allow optimal use of address space and + * establish proper alignment when this function is called first time after + * boot (last section not fully populated at boot time may contains unused + * memory pages with PG_reserved bit not set; online_pages() does not allow + * page onlining in whole section if first page does not have PG_reserved + * bit set). Real size of added memory is established at page onlining stage. + */ + +static enum bp_state reserve_additional_memory(long credit) +{ + int nid, rc; + u64 start; + unsigned long balloon_hotplug = credit; + + start = PFN_PHYS(SECTION_ALIGN_UP(max_pfn)); + balloon_hotplug = (balloon_hotplug & PAGE_SECTION_MASK) + PAGES_PER_SECTION; + nid = memory_add_physaddr_to_nid(start); + + rc = add_memory(nid, start, balloon_hotplug << PAGE_SHIFT); + + if (rc) { + pr_info("xen_balloon: %s: add_memory() failed: %i\n", __func__, rc); + return BP_EAGAIN; + } + + balloon_hotplug -= credit; + + balloon_stats.hotplug_pages += credit; + balloon_stats.balloon_hotplug = balloon_hotplug; + + return BP_DONE; +} + +static int xen_online_page_notifier(struct notifier_block *nb, unsigned long val, void *v) +{ + struct page *page = v; + + __online_page_increment_counters(page, OP_DO_NOT_INCREMENT_TOTAL_COUNTERS); + + mutex_lock(&balloon_mutex); + + __balloon_append(page); + + if (balloon_stats.hotplug_pages) + --balloon_stats.hotplug_pages; + else + --balloon_stats.balloon_hotplug; + + mutex_unlock(&balloon_mutex); + + return NOTIFY_STOP; +} + +static struct notifier_block xen_online_page_nb = { + .notifier_call = xen_online_page_notifier, + .priority = 10 +}; + +static int xen_memory_notifier(struct notifier_block *nb, unsigned long val, void *v) +{ + if (val == MEM_ONLINE) + schedule_delayed_work(&balloon_worker, 0); + + return NOTIFY_OK; +} + +static struct notifier_block xen_memory_nb = { + .notifier_call = xen_memory_notifier, + .priority = 0 +}; +#else static long current_credit(void) { unsigned long target = balloon_stats.target_pages; @@ -206,6 +305,21 @@ static long current_credit(void) return target - balloon_stats.current_pages; } +static int balloon_is_inflated(void) +{ + if (balloon_stats.balloon_low || balloon_stats.balloon_high) + return 1; + else + return 0; +} + +static enum bp_state reserve_additional_memory(long credit) +{ + balloon_stats.target_pages = balloon_stats.current_pages; + return BP_DONE; +} +#endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */ + static enum bp_state increase_reservation(unsigned long nr_pages) { int rc; @@ -217,6 +331,15 @@ static enum bp_state increase_reservation(unsigned long nr_pages) .domid = DOMID_SELF }; +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG + if (!balloon_stats.balloon_low && !balloon_stats.balloon_high) { + nr_pages = min(nr_pages, balloon_stats.balloon_hotplug); + balloon_stats.hotplug_pages += nr_pages; + balloon_stats.balloon_hotplug -= nr_pages; + return BP_DONE; + } +#endif + if (nr_pages > ARRAY_SIZE(frame_list)) nr_pages = ARRAY_SIZE(frame_list); @@ -279,6 +402,15 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) .domid = DOMID_SELF }; +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG + if (balloon_stats.hotplug_pages) { + nr_pages = min(nr_pages, balloon_stats.hotplug_pages); + balloon_stats.hotplug_pages -= nr_pages; + balloon_stats.balloon_hotplug += nr_pages; + return BP_DONE; + } +#endif + if (nr_pages > ARRAY_SIZE(frame_list)) nr_pages = ARRAY_SIZE(frame_list); @@ -340,8 +472,12 @@ static void balloon_process(struct work_struct *work) do { credit = current_credit(); - if (credit > 0) - state = increase_reservation(credit); + if (credit > 0) { + if (balloon_is_inflated()) + state = increase_reservation(credit); + else + state = reserve_additional_memory(credit); + } if (credit < 0) state = decrease_reservation(-credit, GFP_BALLOON); @@ -448,6 +584,14 @@ static int __init balloon_init(void) balloon_stats.retry_count = 1; balloon_stats.max_retry_count = RETRY_UNLIMITED; +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG + balloon_stats.hotplug_pages = 0; + balloon_stats.balloon_hotplug = 0; + + register_online_page_notifier(&xen_online_page_nb); + register_memory_notifier(&xen_memory_nb); +#endif + /* * Initialise the balloon with excess memory space. We need * to make sure we don't add memory which doesn't exist or diff --git a/include/xen/balloon.h b/include/xen/balloon.h index a2b22f0..aeca6ae 100644 --- a/include/xen/balloon.h +++ b/include/xen/balloon.h @@ -15,6 +15,10 @@ struct balloon_stats { unsigned long max_schedule_delay; unsigned long retry_count; unsigned long max_retry_count; +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG + unsigned long hotplug_pages; + unsigned long balloon_hotplug; +#endif }; extern struct balloon_stats balloon_stats; -- 1.5.6.5 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>