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-rw-r--r--mm/damon/reclaim.c284
1 files changed, 284 insertions, 0 deletions
diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
new file mode 100644
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--- /dev/null
+++ b/mm/damon/reclaim.c
@@ -0,0 +1,284 @@
+// 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>
+
+#include "modules-common.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;
+
+/*
+ * Make DAMON_RECLAIM reads the input parameters again, except ``enabled``.
+ *
+ * Input parameters that updated while DAMON_RECLAIM is running are not applied
+ * by default. Once this parameter is set as ``Y``, DAMON_RECLAIM reads values
+ * of parametrs except ``enabled`` again. Once the re-reading is done, this
+ * parameter is set as ``N``. If invalid parameters are found while the
+ * re-reading, DAMON_RECLAIM will be disabled.
+ */
+static bool commit_inputs __read_mostly;
+module_param(commit_inputs, 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);
+
+static struct damos_quota damon_reclaim_quota = {
+ /* use up to 10 ms time, reclaim up to 128 MiB per 1 sec by default */
+ .ms = 10,
+ .sz = 128 * 1024 * 1024,
+ .reset_interval = 1000,
+ /* Within the quota, page out older regions first. */
+ .weight_sz = 0,
+ .weight_nr_accesses = 0,
+ .weight_age = 1
+};
+DEFINE_DAMON_MODULES_DAMOS_QUOTAS(damon_reclaim_quota);
+
+static struct damos_watermarks damon_reclaim_wmarks = {
+ .metric = DAMOS_WMARK_FREE_MEM_RATE,
+ .interval = 5000000, /* 5 seconds */
+ .high = 500, /* 50 percent */
+ .mid = 400, /* 40 percent */
+ .low = 200, /* 20 percent */
+};
+DEFINE_DAMON_MODULES_WMARKS_PARAMS(damon_reclaim_wmarks);
+
+static struct damon_attrs damon_reclaim_mon_attrs = {
+ .sample_interval = 5000, /* 5 ms */
+ .aggr_interval = 100000, /* 100 ms */
+ .ops_update_interval = 0,
+ .min_nr_regions = 10,
+ .max_nr_regions = 1000,
+};
+DEFINE_DAMON_MODULES_MON_ATTRS_PARAMS(damon_reclaim_mon_attrs);
+
+/*
+ * 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 damos_stat damon_reclaim_stat;
+DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_reclaim_stat,
+ reclaim_tried_regions, reclaimed_regions, quota_exceeds);
+
+static struct damon_ctx *ctx;
+static struct damon_target *target;
+
+static struct damos *damon_reclaim_new_scheme(void)
+{
+ struct damos_access_pattern pattern = {
+ /* Find regions having PAGE_SIZE or larger size */
+ .min_sz_region = PAGE_SIZE,
+ .max_sz_region = ULONG_MAX,
+ /* and not accessed at all */
+ .min_nr_accesses = 0,
+ .max_nr_accesses = 0,
+ /* for min_age or more micro-seconds */
+ .min_age_region = min_age /
+ damon_reclaim_mon_attrs.aggr_interval,
+ .max_age_region = UINT_MAX,
+ };
+
+ return damon_new_scheme(
+ &pattern,
+ /* page out those, as soon as found */
+ DAMOS_PAGEOUT,
+ /* under the quota. */
+ &damon_reclaim_quota,
+ /* (De)activate this according to the watermarks. */
+ &damon_reclaim_wmarks);
+}
+
+static int damon_reclaim_apply_parameters(void)
+{
+ struct damos *scheme;
+ int err = 0;
+
+ err = damon_set_attrs(ctx, &damon_reclaim_mon_attrs);
+ if (err)
+ return err;
+
+ /* Will be freed by next 'damon_set_schemes()' below */
+ scheme = damon_reclaim_new_scheme();
+ if (!scheme)
+ return -ENOMEM;
+ damon_set_schemes(ctx, &scheme, 1);
+
+ return damon_set_region_biggest_system_ram_default(target,
+ &monitor_region_start,
+ &monitor_region_end);
+}
+
+static int damon_reclaim_turn(bool on)
+{
+ int err;
+
+ if (!on) {
+ err = damon_stop(&ctx, 1);
+ if (!err)
+ kdamond_pid = -1;
+ return err;
+ }
+
+ err = damon_reclaim_apply_parameters();
+ if (err)
+ return err;
+
+ err = damon_start(&ctx, 1, true);
+ if (err)
+ return err;
+ kdamond_pid = ctx->kdamond->pid;
+ return 0;
+}
+
+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;
+ }
+}
+static DECLARE_DELAYED_WORK(damon_reclaim_timer, damon_reclaim_timer_fn);
+
+static bool damon_reclaim_initialized;
+
+static int damon_reclaim_enabled_store(const char *val,
+ const struct kernel_param *kp)
+{
+ int rc = param_set_bool(val, kp);
+
+ if (rc < 0)
+ return rc;
+
+ /* system_wq might not initialized yet */
+ if (!damon_reclaim_initialized)
+ return rc;
+
+ schedule_delayed_work(&damon_reclaim_timer, 0);
+ return 0;
+}
+
+static const struct kernel_param_ops enabled_param_ops = {
+ .set = damon_reclaim_enabled_store,
+ .get = param_get_bool,
+};
+
+module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);
+MODULE_PARM_DESC(enabled,
+ "Enable or disable DAMON_RECLAIM (default: disabled)");
+
+static int damon_reclaim_handle_commit_inputs(void)
+{
+ int err;
+
+ if (!commit_inputs)
+ return 0;
+
+ err = damon_reclaim_apply_parameters();
+ commit_inputs = false;
+ return err;
+}
+
+static int damon_reclaim_after_aggregation(struct damon_ctx *c)
+{
+ struct damos *s;
+
+ /* update the stats parameter */
+ damon_for_each_scheme(s, c)
+ damon_reclaim_stat = s->stat;
+
+ return damon_reclaim_handle_commit_inputs();
+}
+
+static int damon_reclaim_after_wmarks_check(struct damon_ctx *c)
+{
+ return damon_reclaim_handle_commit_inputs();
+}
+
+static int __init damon_reclaim_init(void)
+{
+ ctx = damon_new_ctx();
+ if (!ctx)
+ return -ENOMEM;
+
+ if (damon_select_ops(ctx, DAMON_OPS_PADDR)) {
+ damon_destroy_ctx(ctx);
+ return -EINVAL;
+ }
+
+ ctx->callback.after_wmarks_check = damon_reclaim_after_wmarks_check;
+ ctx->callback.after_aggregation = damon_reclaim_after_aggregation;
+
+ target = damon_new_target();
+ if (!target) {
+ damon_destroy_ctx(ctx);
+ return -ENOMEM;
+ }
+ damon_add_target(ctx, target);
+
+ schedule_delayed_work(&damon_reclaim_timer, 0);
+
+ damon_reclaim_initialized = true;
+ return 0;
+}
+
+module_init(damon_reclaim_init);