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Diffstat (limited to 'mm/damon/reclaim.c')
| -rw-r--r-- | mm/damon/reclaim.c | 356 |
1 files changed, 356 insertions, 0 deletions
diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c new file mode 100644 index 000000000000..dc1485044eaf --- /dev/null +++ b/mm/damon/reclaim.c @@ -0,0 +1,356 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * DAMON-based page reclamation + * + * Author: SeongJae Park <sj@kernel.org> + */ + +#define pr_fmt(fmt) "damon-reclaim: " fmt + +#include <linux/damon.h> +#include <linux/ioport.h> +#include <linux/module.h> +#include <linux/sched.h> +#include <linux/workqueue.h> + +#ifdef MODULE_PARAM_PREFIX +#undef MODULE_PARAM_PREFIX +#endif +#define MODULE_PARAM_PREFIX "damon_reclaim." + +/* + * Enable or disable DAMON_RECLAIM. + * + * You can enable DAMON_RCLAIM by setting the value of this parameter as ``Y``. + * Setting it as ``N`` disables DAMON_RECLAIM. Note that DAMON_RECLAIM could + * do no real monitoring and reclamation due to the watermarks-based activation + * condition. Refer to below descriptions for the watermarks parameter for + * this. + */ +static bool enabled __read_mostly; +module_param(enabled, bool, 0600); + +/* + * Time threshold for cold memory regions identification in microseconds. + * + * If a memory region is not accessed for this or longer time, DAMON_RECLAIM + * identifies the region as cold, and reclaims. 120 seconds by default. + */ +static unsigned long min_age __read_mostly = 120000000; +module_param(min_age, ulong, 0600); + +/* + * Limit of time for trying the reclamation in milliseconds. + * + * DAMON_RECLAIM tries to use only up to this time within a time window + * (quota_reset_interval_ms) for trying reclamation of cold pages. This can be + * used for limiting CPU consumption of DAMON_RECLAIM. If the value is zero, + * the limit is disabled. + * + * 10 ms by default. + */ +static unsigned long quota_ms __read_mostly = 10; +module_param(quota_ms, ulong, 0600); + +/* + * Limit of size of memory for the reclamation in bytes. + * + * DAMON_RECLAIM charges amount of memory which it tried to reclaim within a + * time window (quota_reset_interval_ms) and makes no more than this limit is + * tried. This can be used for limiting consumption of CPU and IO. If this + * value is zero, the limit is disabled. + * + * 128 MiB by default. + */ +static unsigned long quota_sz __read_mostly = 128 * 1024 * 1024; +module_param(quota_sz, ulong, 0600); + +/* + * The time/size quota charge reset interval in milliseconds. + * + * The charge reset interval for the quota of time (quota_ms) and size + * (quota_sz). That is, DAMON_RECLAIM does not try reclamation for more than + * quota_ms milliseconds or quota_sz bytes within quota_reset_interval_ms + * milliseconds. + * + * 1 second by default. + */ +static unsigned long quota_reset_interval_ms __read_mostly = 1000; +module_param(quota_reset_interval_ms, ulong, 0600); + +/* + * The watermarks check time interval in microseconds. + * + * Minimal time to wait before checking the watermarks, when DAMON_RECLAIM is + * enabled but inactive due to its watermarks rule. 5 seconds by default. + */ +static unsigned long wmarks_interval __read_mostly = 5000000; +module_param(wmarks_interval, ulong, 0600); + +/* + * Free memory rate (per thousand) for the high watermark. + * + * If free memory of the system in bytes per thousand bytes is higher than + * this, DAMON_RECLAIM becomes inactive, so it does nothing but periodically + * checks the watermarks. 500 (50%) by default. + */ +static unsigned long wmarks_high __read_mostly = 500; +module_param(wmarks_high, ulong, 0600); + +/* + * Free memory rate (per thousand) for the middle watermark. + * + * If free memory of the system in bytes per thousand bytes is between this and + * the low watermark, DAMON_RECLAIM becomes active, so starts the monitoring + * and the reclaiming. 400 (40%) by default. + */ +static unsigned long wmarks_mid __read_mostly = 400; +module_param(wmarks_mid, ulong, 0600); + +/* + * Free memory rate (per thousand) for the low watermark. + * + * If free memory of the system in bytes per thousand bytes is lower than this, + * DAMON_RECLAIM becomes inactive, so it does nothing but periodically checks + * the watermarks. In the case, the system falls back to the LRU-based page + * granularity reclamation logic. 200 (20%) by default. + */ +static unsigned long wmarks_low __read_mostly = 200; +module_param(wmarks_low, ulong, 0600); + +/* + * Sampling interval for the monitoring in microseconds. + * + * The sampling interval of DAMON for the cold memory monitoring. Please refer + * to the DAMON documentation for more detail. 5 ms by default. + */ +static unsigned long sample_interval __read_mostly = 5000; +module_param(sample_interval, ulong, 0600); + +/* + * Aggregation interval for the monitoring in microseconds. + * + * The aggregation interval of DAMON for the cold memory monitoring. Please + * refer to the DAMON documentation for more detail. 100 ms by default. + */ +static unsigned long aggr_interval __read_mostly = 100000; +module_param(aggr_interval, ulong, 0600); + +/* + * Minimum number of monitoring regions. + * + * The minimal number of monitoring regions of DAMON for the cold memory + * monitoring. This can be used to set lower-bound of the monitoring quality. + * But, setting this too high could result in increased monitoring overhead. + * Please refer to the DAMON documentation for more detail. 10 by default. + */ +static unsigned long min_nr_regions __read_mostly = 10; +module_param(min_nr_regions, ulong, 0600); + +/* + * Maximum number of monitoring regions. + * + * The maximum number of monitoring regions of DAMON for the cold memory + * monitoring. This can be used to set upper-bound of the monitoring overhead. + * However, setting this too low could result in bad monitoring quality. + * Please refer to the DAMON documentation for more detail. 1000 by default. + */ +static unsigned long max_nr_regions __read_mostly = 1000; +module_param(max_nr_regions, ulong, 0600); + +/* + * Start of the target memory region in physical address. + * + * The start physical address of memory region that DAMON_RECLAIM will do work + * against. By default, biggest System RAM is used as the region. + */ +static unsigned long monitor_region_start __read_mostly; +module_param(monitor_region_start, ulong, 0600); + +/* + * End of the target memory region in physical address. + * + * The end physical address of memory region that DAMON_RECLAIM will do work + * against. By default, biggest System RAM is used as the region. + */ +static unsigned long monitor_region_end __read_mostly; +module_param(monitor_region_end, ulong, 0600); + +/* + * PID of the DAMON thread + * + * If DAMON_RECLAIM is enabled, this becomes the PID of the worker thread. + * Else, -1. + */ +static int kdamond_pid __read_mostly = -1; +module_param(kdamond_pid, int, 0400); + +static struct damon_ctx *ctx; +static struct damon_target *target; + +struct damon_reclaim_ram_walk_arg { + unsigned long start; + unsigned long end; +}; + +static int walk_system_ram(struct resource *res, void *arg) +{ + struct damon_reclaim_ram_walk_arg *a = arg; + + if (a->end - a->start < res->end - res->start) { + a->start = res->start; + a->end = res->end; + } + return 0; +} + +/* + * Find biggest 'System RAM' resource and store its start and end address in + * @start and @end, respectively. If no System RAM is found, returns false. + */ +static bool get_monitoring_region(unsigned long *start, unsigned long *end) +{ + struct damon_reclaim_ram_walk_arg arg = {}; + + walk_system_ram_res(0, ULONG_MAX, &arg, walk_system_ram); + if (arg.end <= arg.start) + return false; + + *start = arg.start; + *end = arg.end; + return true; +} + +static struct damos *damon_reclaim_new_scheme(void) +{ + struct damos_watermarks wmarks = { + .metric = DAMOS_WMARK_FREE_MEM_RATE, + .interval = wmarks_interval, + .high = wmarks_high, + .mid = wmarks_mid, + .low = wmarks_low, + }; + struct damos_quota quota = { + /* + * Do not try reclamation for more than quota_ms milliseconds + * or quota_sz bytes within quota_reset_interval_ms. + */ + .ms = quota_ms, + .sz = quota_sz, + .reset_interval = quota_reset_interval_ms, + /* Within the quota, page out older regions first. */ + .weight_sz = 0, + .weight_nr_accesses = 0, + .weight_age = 1 + }; + struct damos *scheme = damon_new_scheme( + /* Find regions having PAGE_SIZE or larger size */ + PAGE_SIZE, ULONG_MAX, + /* and not accessed at all */ + 0, 0, + /* for min_age or more micro-seconds, and */ + min_age / aggr_interval, UINT_MAX, + /* page out those, as soon as found */ + DAMOS_PAGEOUT, + /* under the quota. */ + "a, + /* (De)activate this according to the watermarks. */ + &wmarks); + + return scheme; +} + +static int damon_reclaim_turn(bool on) +{ + struct damon_region *region; + struct damos *scheme; + int err; + + if (!on) { + err = damon_stop(&ctx, 1); + if (!err) + kdamond_pid = -1; + return err; + } + + err = damon_set_attrs(ctx, sample_interval, aggr_interval, 0, + min_nr_regions, max_nr_regions); + if (err) + return err; + + if (monitor_region_start > monitor_region_end) + return -EINVAL; + if (!monitor_region_start && !monitor_region_end && + !get_monitoring_region(&monitor_region_start, + &monitor_region_end)) + return -EINVAL; + /* DAMON will free this on its own when finish monitoring */ + region = damon_new_region(monitor_region_start, monitor_region_end); + if (!region) + return -ENOMEM; + damon_add_region(region, target); + + /* Will be freed by 'damon_set_schemes()' below */ + scheme = damon_reclaim_new_scheme(); + if (!scheme) { + err = -ENOMEM; + goto free_region_out; + } + err = damon_set_schemes(ctx, &scheme, 1); + if (err) + goto free_scheme_out; + + err = damon_start(&ctx, 1); + if (!err) { + kdamond_pid = ctx->kdamond->pid; + return 0; + } + +free_scheme_out: + damon_destroy_scheme(scheme); +free_region_out: + damon_destroy_region(region, target); + return err; +} + +#define ENABLE_CHECK_INTERVAL_MS 1000 +static struct delayed_work damon_reclaim_timer; +static void damon_reclaim_timer_fn(struct work_struct *work) +{ + static bool last_enabled; + bool now_enabled; + + now_enabled = enabled; + if (last_enabled != now_enabled) { + if (!damon_reclaim_turn(now_enabled)) + last_enabled = now_enabled; + else + enabled = last_enabled; + } + + schedule_delayed_work(&damon_reclaim_timer, + msecs_to_jiffies(ENABLE_CHECK_INTERVAL_MS)); +} +static DECLARE_DELAYED_WORK(damon_reclaim_timer, damon_reclaim_timer_fn); + +static int __init damon_reclaim_init(void) +{ + ctx = damon_new_ctx(); + if (!ctx) + return -ENOMEM; + + damon_pa_set_primitives(ctx); + + /* 4242 means nothing but fun */ + target = damon_new_target(4242); + if (!target) { + damon_destroy_ctx(ctx); + return -ENOMEM; + } + damon_add_target(ctx, target); + + schedule_delayed_work(&damon_reclaim_timer, 0); + return 0; +} + +module_init(damon_reclaim_init); |