diff options
| -rw-r--r-- | drivers/xen/balloon.c | 107 |
1 files changed, 90 insertions, 17 deletions
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 9206ff7514e..6cd2530f233 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -66,6 +66,22 @@ #define BALLOON_CLASS_NAME "xen_memory" +/* + * balloon_process() state: + * + * BP_DONE: done or nothing to do, + * BP_EAGAIN: error, go to sleep, + * BP_ECANCELED: error, balloon operation canceled. + */ + +enum bp_state { + BP_DONE, + BP_EAGAIN, + BP_ECANCELED +}; + +#define RETRY_UNLIMITED 0 + struct balloon_stats { /* We aim for 'current allocation' == 'target allocation'. */ unsigned long current_pages; @@ -73,6 +89,10 @@ struct balloon_stats { /* Number of pages in high- and low-memory balloons. */ unsigned long balloon_low; unsigned long balloon_high; + unsigned long schedule_delay; + unsigned long max_schedule_delay; + unsigned long retry_count; + unsigned long max_retry_count; }; static DEFINE_MUTEX(balloon_mutex); @@ -171,6 +191,36 @@ static struct page *balloon_next_page(struct page *page) return list_entry(next, struct page, lru); } +static enum bp_state update_schedule(enum bp_state state) +{ + if (state == BP_DONE) { + balloon_stats.schedule_delay = 1; + balloon_stats.retry_count = 1; + return BP_DONE; + } + + pr_info("xen_balloon: Retry count: %lu/%lu\n", balloon_stats.retry_count, + balloon_stats.max_retry_count); + + ++balloon_stats.retry_count; + + if (balloon_stats.max_retry_count != RETRY_UNLIMITED && + balloon_stats.retry_count > balloon_stats.max_retry_count) { + pr_info("xen_balloon: Retry count limit exceeded\n" + "xen_balloon: Balloon operation canceled\n"); + balloon_stats.schedule_delay = 1; + balloon_stats.retry_count = 1; + return BP_ECANCELED; + } + + balloon_stats.schedule_delay <<= 1; + + if (balloon_stats.schedule_delay > balloon_stats.max_schedule_delay) + balloon_stats.schedule_delay = balloon_stats.max_schedule_delay; + + return BP_EAGAIN; +} + static unsigned long current_target(void) { unsigned long target = balloon_stats.target_pages; @@ -183,11 +233,11 @@ static unsigned long current_target(void) return target; } -static int increase_reservation(unsigned long nr_pages) +static enum bp_state increase_reservation(unsigned long nr_pages) { + int rc; unsigned long pfn, i; struct page *page; - long rc; struct xen_memory_reservation reservation = { .address_bits = 0, .extent_order = 0, @@ -199,7 +249,10 @@ static int increase_reservation(unsigned long nr_pages) page = balloon_first_page(); for (i = 0; i < nr_pages; i++) { - BUG_ON(page == NULL); + if (!page) { + nr_pages = i; + break; + } frame_list[i] = page_to_pfn(page); page = balloon_next_page(page); } @@ -207,8 +260,10 @@ static int increase_reservation(unsigned long nr_pages) set_xen_guest_handle(reservation.extent_start, frame_list); reservation.nr_extents = nr_pages; rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation); - if (rc < 0) - goto out; + if (rc <= 0) { + pr_info("xen_balloon: %s: Cannot allocate memory\n", __func__); + return BP_EAGAIN; + } for (i = 0; i < rc; i++) { page = balloon_retrieve(); @@ -238,15 +293,14 @@ static int increase_reservation(unsigned long nr_pages) balloon_stats.current_pages += rc; - out: - return rc < 0 ? rc : rc != nr_pages; + return BP_DONE; } -static int decrease_reservation(unsigned long nr_pages) +static enum bp_state decrease_reservation(unsigned long nr_pages) { + enum bp_state state = BP_DONE; unsigned long pfn, i; struct page *page; - int need_sleep = 0; int ret; struct xen_memory_reservation reservation = { .address_bits = 0, @@ -259,8 +313,9 @@ static int decrease_reservation(unsigned long nr_pages) for (i = 0; i < nr_pages; i++) { if ((page = alloc_page(GFP_BALLOON)) == NULL) { + pr_info("xen_balloon: %s: Cannot allocate memory\n", __func__); nr_pages = i; - need_sleep = 1; + state = BP_EAGAIN; break; } @@ -296,7 +351,7 @@ static int decrease_reservation(unsigned long nr_pages) balloon_stats.current_pages -= nr_pages; - return need_sleep; + return state; } /* @@ -307,27 +362,31 @@ static int decrease_reservation(unsigned long nr_pages) */ static void balloon_process(struct work_struct *work) { - int need_sleep = 0; + enum bp_state state = BP_DONE; long credit; mutex_lock(&balloon_mutex); do { credit = current_target() - balloon_stats.current_pages; + if (credit > 0) - need_sleep = (increase_reservation(credit) != 0); + state = increase_reservation(credit); + if (credit < 0) - need_sleep = (decrease_reservation(-credit) != 0); + state = decrease_reservation(-credit); + + state = update_schedule(state); #ifndef CONFIG_PREEMPT if (need_resched()) schedule(); #endif - } while ((credit != 0) && !need_sleep); + } while (credit && state == BP_DONE); /* Schedule more work if there is some still to be done. */ - if (current_target() != balloon_stats.current_pages) - schedule_delayed_work(&balloon_worker, HZ); + if (state == BP_EAGAIN) + schedule_delayed_work(&balloon_worker, balloon_stats.schedule_delay * HZ); mutex_unlock(&balloon_mutex); } @@ -394,6 +453,11 @@ static int __init balloon_init(void) balloon_stats.balloon_low = 0; balloon_stats.balloon_high = 0; + balloon_stats.schedule_delay = 1; + balloon_stats.max_schedule_delay = 32; + balloon_stats.retry_count = 1; + balloon_stats.max_retry_count = 16; + register_balloon(&balloon_sysdev); /* @@ -447,6 +511,11 @@ BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages)); BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low)); BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high)); +static SYSDEV_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay); +static SYSDEV_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay); +static SYSDEV_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count); +static SYSDEV_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count); + static ssize_t show_target_kb(struct sys_device *dev, struct sysdev_attribute *attr, char *buf) { @@ -508,6 +577,10 @@ static SYSDEV_ATTR(target, S_IRUGO | S_IWUSR, static struct sysdev_attribute *balloon_attrs[] = { &attr_target_kb, &attr_target, + &attr_schedule_delay.attr, + &attr_max_schedule_delay.attr, + &attr_retry_count.attr, + &attr_max_retry_count.attr }; static struct attribute *balloon_info_attrs[] = { |