1 files changed, 398 insertions, 0 deletions
diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
new file mode 100644
index 000000000000..36a582e09eae
--- /dev/null
+++ b/mm/damon/reclaim.c
@@ -0,0 +1,398 @@
+// 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/kstrtox.h>
+#include <linux/module.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);
+
+/*
+ * Desired level of memory pressure-stall time in microseconds.
+ *
+ * While keeping the caps that set by other quotas, DAMON_RECLAIM automatically
+ * increases and decreases the effective level of the quota aiming this level of
+ * memory pressure is incurred.  System-wide ``some`` memory PSI in microseconds
+ * per quota reset interval (``quota_reset_interval_ms``) is collected and
+ * compared to this value to see if the aim is satisfied.  Value zero means
+ * disabling this auto-tuning feature.
+ *
+ * Disabled by default.
+ */
+static unsigned long quota_mem_pressure_us __read_mostly;
+module_param(quota_mem_pressure_us, ulong, 0600);
+
+/*
+ * User-specifiable feedback for auto-tuning of the effective quota.
+ *
+ * While keeping the caps that set by other quotas, DAMON_RECLAIM automatically
+ * increases and decreases the effective level of the quota aiming receiving this
+ * feedback of value ``10,000`` from the user.  DAMON_RECLAIM assumes the feedback
+ * value and the quota are positively proportional.  Value zero means disabling
+ * this auto-tuning feature.
+ *
+ * Disabled by default.
+ *
+ */
+static unsigned long quota_autotune_feedback __read_mostly;
+module_param(quota_autotune_feedback, ulong, 0600);
+
+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);
+
+/*
+ * Scale factor for DAMON_RECLAIM to ops address conversion.
+ *
+ * This parameter must not be set to 0.
+ */
+static unsigned long addr_unit __read_mostly = 1;
+
+/*
+ * Skip anonymous pages reclamation.
+ *
+ * If this parameter is set as ``Y``, DAMON_RECLAIM does not reclaim anonymous
+ * pages.  By default, ``N``.
+ */
+static bool skip_anon __read_mostly;
+module_param(skip_anon, bool, 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,
+			/* for each aggregation interval */
+			0,
+			/* under the quota. */
+			&damon_reclaim_quota,
+			/* (De)activate this according to the watermarks. */
+			&damon_reclaim_wmarks,
+			NUMA_NO_NODE);
+}
+
+static int damon_reclaim_apply_parameters(void)
+{
+	struct damon_ctx *param_ctx;
+	struct damon_target *param_target;
+	struct damos *scheme;
+	struct damos_quota_goal *goal;
+	struct damos_filter *filter;
+	int err;
+
+	err = damon_modules_new_paddr_ctx_target(&param_ctx, &param_target);
+	if (err)
+		return err;
+
+	/*
+	 * If monitor_region_start/end are unset, always silently
+	 * reset addr_unit to 1.
+	 */
+	if (!monitor_region_start && !monitor_region_end)
+		addr_unit = 1;
+	param_ctx->addr_unit = addr_unit;
+	param_ctx->min_sz_region = max(DAMON_MIN_REGION / addr_unit, 1);
+
+	if (!damon_reclaim_mon_attrs.aggr_interval) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	err = damon_set_attrs(param_ctx, &damon_reclaim_mon_attrs);
+	if (err)
+		goto out;
+
+	err = -ENOMEM;
+	scheme = damon_reclaim_new_scheme();
+	if (!scheme)
+		goto out;
+	damon_set_schemes(param_ctx, &scheme, 1);
+
+	if (quota_mem_pressure_us) {
+		goal = damos_new_quota_goal(DAMOS_QUOTA_SOME_MEM_PSI_US,
+				quota_mem_pressure_us);
+		if (!goal)
+			goto out;
+		damos_add_quota_goal(&scheme->quota, goal);
+	}
+
+	if (quota_autotune_feedback) {
+		goal = damos_new_quota_goal(DAMOS_QUOTA_USER_INPUT, 10000);
+		if (!goal)
+			goto out;
+		goal->current_value = quota_autotune_feedback;
+		damos_add_quota_goal(&scheme->quota, goal);
+	}
+
+	if (skip_anon) {
+		filter = damos_new_filter(DAMOS_FILTER_TYPE_ANON, true, false);
+		if (!filter)
+			goto out;
+		damos_add_filter(scheme, filter);
+	}
+
+	err = damon_set_region_biggest_system_ram_default(param_target,
+					&monitor_region_start,
+					&monitor_region_end,
+					param_ctx->min_sz_region);
+	if (err)
+		goto out;
+	err = damon_commit_ctx(ctx, param_ctx);
+out:
+	damon_destroy_ctx(param_ctx);
+	return err;
+}
+
+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_damon_call_fn(void *arg)
+{
+	struct damon_ctx *c = arg;
+	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 struct damon_call_control call_control = {
+	.fn = damon_reclaim_damon_call_fn,
+	.repeat = true,
+};
+
+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 damon_call(ctx, &call_control);
+}
+
+static int damon_reclaim_addr_unit_store(const char *val,
+		const struct kernel_param *kp)
+{
+	unsigned long input_addr_unit;
+	int err = kstrtoul(val, 0, &input_addr_unit);
+
+	if (err)
+		return err;
+	if (!input_addr_unit)
+		return -EINVAL;
+
+	addr_unit = input_addr_unit;
+	return 0;
+}
+
+static const struct kernel_param_ops addr_unit_param_ops = {
+	.set = damon_reclaim_addr_unit_store,
+	.get = param_get_ulong,
+};
+
+module_param_cb(addr_unit, &addr_unit_param_ops, &addr_unit, 0600);
+MODULE_PARM_DESC(addr_unit,
+	"Scale factor for DAMON_RECLAIM to ops address conversion (default: 1)");
+
+static int damon_reclaim_enabled_store(const char *val,
+		const struct kernel_param *kp)
+{
+	bool is_enabled = enabled;
+	bool enable;
+	int err;
+
+	err = kstrtobool(val, &enable);
+	if (err)
+		return err;
+
+	if (is_enabled == enable)
+		return 0;
+
+	/* Called before init function.  The function will handle this. */
+	if (!damon_initialized())
+		goto set_param_out;
+
+	err = damon_reclaim_turn(enable);
+	if (err)
+		return err;
+
+set_param_out:
+	enabled = enable;
+	return err;
+}
+
+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 __init damon_reclaim_init(void)
+{
+	int err;
+
+	if (!damon_initialized()) {
+		err = -ENOMEM;
+		goto out;
+	}
+	err = damon_modules_new_paddr_ctx_target(&ctx, &target);
+	if (err)
+		goto out;
+
+	call_control.data = ctx;
+
+	/* 'enabled' has set before this function, probably via command line */
+	if (enabled)
+		err = damon_reclaim_turn(true);
+
+out:
+	if (err && enabled)
+		enabled = false;
+	return err;
+}
+
+module_init(damon_reclaim_init);