1 files changed, 284 insertions, 0 deletions
diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
new file mode 100644
index 000000000..162c9b1ca
--- /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);