diff options
| -rw-r--r-- | drivers/xen/xen-selfballoon.c | 67 |
1 files changed, 63 insertions, 4 deletions
diff --git a/drivers/xen/xen-selfballoon.c b/drivers/xen/xen-selfballoon.c index 1b4afd81f872..ff3f2e423af4 100644 --- a/drivers/xen/xen-selfballoon.c +++ b/drivers/xen/xen-selfballoon.c @@ -68,6 +68,8 @@ */ #include <linux/kernel.h> +#include <linux/bootmem.h> +#include <linux/swap.h> #include <linux/mm.h> #include <linux/mman.h> #include <linux/workqueue.h> @@ -92,6 +94,15 @@ static unsigned int selfballoon_uphysteresis __read_mostly = 1; /* In HZ, controls frequency of worker invocation. */ static unsigned int selfballoon_interval __read_mostly = 5; +/* + * Minimum usable RAM in MB for selfballooning target for balloon. + * If non-zero, it is added to totalreserve_pages and self-ballooning + * will not balloon below the sum. If zero, a piecewise linear function + * is calculated as a minimum and added to totalreserve_pages. Note that + * setting this value indiscriminately may cause OOMs and crashes. + */ +static unsigned int selfballoon_min_usable_mb; + static void selfballoon_process(struct work_struct *work); static DECLARE_DELAYED_WORK(selfballoon_worker, selfballoon_process); @@ -188,20 +199,23 @@ static int __init xen_selfballooning_setup(char *s) __setup("selfballooning", xen_selfballooning_setup); #endif /* CONFIG_FRONTSWAP */ +#define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT)) + /* * Use current balloon size, the goal (vm_committed_as), and hysteresis * parameters to set a new target balloon size */ static void selfballoon_process(struct work_struct *work) { - unsigned long cur_pages, goal_pages, tgt_pages; + unsigned long cur_pages, goal_pages, tgt_pages, floor_pages; + unsigned long useful_pages; bool reset_timer = false; if (xen_selfballooning_enabled) { - cur_pages = balloon_stats.current_pages; + cur_pages = totalram_pages; tgt_pages = cur_pages; /* default is no change */ goal_pages = percpu_counter_read_positive(&vm_committed_as) + - balloon_stats.current_pages - totalram_pages; + totalreserve_pages; #ifdef CONFIG_FRONTSWAP /* allow space for frontswap pages to be repatriated */ if (frontswap_selfshrinking && frontswap_enabled) @@ -216,7 +230,26 @@ static void selfballoon_process(struct work_struct *work) ((goal_pages - cur_pages) / selfballoon_uphysteresis); /* else if cur_pages == goal_pages, no change */ - balloon_set_new_target(tgt_pages); + useful_pages = max_pfn - totalreserve_pages; + if (selfballoon_min_usable_mb != 0) + floor_pages = totalreserve_pages + + MB2PAGES(selfballoon_min_usable_mb); + /* piecewise linear function ending in ~3% slope */ + else if (useful_pages < MB2PAGES(16)) + floor_pages = max_pfn; /* not worth ballooning */ + else if (useful_pages < MB2PAGES(64)) + floor_pages = totalreserve_pages + MB2PAGES(16) + + ((useful_pages - MB2PAGES(16)) >> 1); + else if (useful_pages < MB2PAGES(512)) + floor_pages = totalreserve_pages + MB2PAGES(40) + + ((useful_pages - MB2PAGES(40)) >> 3); + else /* useful_pages >= MB2PAGES(512) */ + floor_pages = totalreserve_pages + MB2PAGES(99) + + ((useful_pages - MB2PAGES(99)) >> 5); + if (tgt_pages < floor_pages) + tgt_pages = floor_pages; + balloon_set_new_target(tgt_pages + + balloon_stats.current_pages - totalram_pages); reset_timer = true; } #ifdef CONFIG_FRONTSWAP @@ -339,6 +372,31 @@ static ssize_t store_selfballoon_uphys(struct sys_device *dev, static SYSDEV_ATTR(selfballoon_uphysteresis, S_IRUGO | S_IWUSR, show_selfballoon_uphys, store_selfballoon_uphys); +SELFBALLOON_SHOW(selfballoon_min_usable_mb, "%d\n", + selfballoon_min_usable_mb); + +static ssize_t store_selfballoon_min_usable_mb(struct sys_device *dev, + struct sysdev_attribute *attr, + const char *buf, + size_t count) +{ + unsigned long val; + int err; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + err = strict_strtoul(buf, 10, &val); + if (err || val == 0) + return -EINVAL; + selfballoon_min_usable_mb = val; + return count; +} + +static SYSDEV_ATTR(selfballoon_min_usable_mb, S_IRUGO | S_IWUSR, + show_selfballoon_min_usable_mb, + store_selfballoon_min_usable_mb); + + #ifdef CONFIG_FRONTSWAP SELFBALLOON_SHOW(frontswap_selfshrinking, "%d\n", frontswap_selfshrinking); @@ -420,6 +478,7 @@ static struct attribute *selfballoon_attrs[] = { &attr_selfballoon_interval.attr, &attr_selfballoon_downhysteresis.attr, &attr_selfballoon_uphysteresis.attr, + &attr_selfballoon_min_usable_mb.attr, #ifdef CONFIG_FRONTSWAP &attr_frontswap_selfshrinking.attr, &attr_frontswap_hysteresis.attr, |