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// 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);
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);
/*
* 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,
/* 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;
struct damos_filter *filter;
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;
if (skip_anon) {
filter = damos_new_filter(DAMOS_FILTER_TYPE_ANON, true);
if (!filter) {
/* Will be freed by next 'damon_set_schemes()' below */
damon_destroy_scheme(scheme);
return -ENOMEM;
}
damos_add_filter(scheme, filter);
}
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 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 (!ctx)
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 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)
{
int err = damon_modules_new_paddr_ctx_target(&ctx, &target);
if (err)
return err;
ctx->callback.after_wmarks_check = damon_reclaim_after_wmarks_check;
ctx->callback.after_aggregation = damon_reclaim_after_aggregation;
/* 'enabled' has set before this function, probably via command line */
if (enabled)
err = damon_reclaim_turn(true);
return err;
}
module_init(damon_reclaim_init);