// SPDX-License-Identifier: GPL-2.0/* * proactive reclamation: monitor access pattern of a given process, find * regions that seems not accessed, and proactively page out the regions. */ #define pr_fmt(fmt) "damon_sample_prcl: " fmt #include <linux/damon.h>#include <linux/init.h>#include <linux/kernel.h>#include <linux/module.h> #ifdef MODULE_PARAM_PREFIX#undef MODULE_PARAM_PREFIX#endif#define MODULE_PARAM_PREFIX "damon_sample_prcl." static int target_pid __read_mostly;module_param(target_pid, int, 0600); static int damon_sample_prcl_enable_store(		const char *val, const struct kernel_param *kp); static const struct kernel_param_ops enabled_param_ops = {	.set = damon_sample_prcl_enable_store,	.get = param_get_bool,}; static bool enabled __read_mostly;module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);MODULE_PARM_DESC(enabled, "Enable or disable DAMON_SAMPLE_PRCL"); static struct damon_ctx *ctx;static struct pid *target_pidp; static int damon_sample_prcl_repeat_call_fn(void *data){	struct damon_ctx *c = data;	struct damon_target *t; 	damon_for_each_target(t, c) {		struct damon_region *r;		unsigned long wss = 0; 		damon_for_each_region(r, t) {			if (r->nr_accesses > 0)				wss += r->ar.end - r->ar.start;		}		pr_info("wss: %lu\n", wss);	}	return 0;} static struct damon_call_control repeat_call_control = {	.fn = damon_sample_prcl_repeat_call_fn,	.repeat = true,}; static int damon_sample_prcl_start(void){	struct damon_target *target;	struct damos *scheme;	int err; 	pr_info("start\n"); 	ctx = damon_new_ctx();	if (!ctx)		return -ENOMEM;	if (damon_select_ops(ctx, DAMON_OPS_VADDR)) {		damon_destroy_ctx(ctx);		return -EINVAL;	} 	target = damon_new_target();	if (!target) {		damon_destroy_ctx(ctx);		return -ENOMEM;	}	damon_add_target(ctx, target);	target_pidp = find_get_pid(target_pid);	if (!target_pidp) {		damon_destroy_ctx(ctx);		return -EINVAL;	}	target->pid = target_pidp; 	scheme = damon_new_scheme(			&(struct damos_access_pattern) {			.min_sz_region = PAGE_SIZE,			.max_sz_region = ULONG_MAX,			.min_nr_accesses = 0,			.max_nr_accesses = 0,			.min_age_region = 50,			.max_age_region = UINT_MAX},			DAMOS_PAGEOUT,			0,			&(struct damos_quota){},			&(struct damos_watermarks){},			NUMA_NO_NODE);	if (!scheme) {		damon_destroy_ctx(ctx);		return -ENOMEM;	}	damon_set_schemes(ctx, &scheme, 1); 	err = damon_start(&ctx, 1, true);	if (err) {		damon_destroy_ctx(ctx);		return err;	} 	repeat_call_control.data = ctx;	err = damon_call(ctx, &repeat_call_control);	if (err)		damon_destroy_ctx(ctx);	return err;} static void damon_sample_prcl_stop(void){	pr_info("stop\n");	if (ctx) {		damon_stop(&ctx, 1);		damon_destroy_ctx(ctx);	}} static int damon_sample_prcl_enable_store(		const char *val, const struct kernel_param *kp){	bool is_enabled = enabled;	int err; 	err = kstrtobool(val, &enabled);	if (err)		return err; 	if (enabled == is_enabled)		return 0; 	if (!damon_initialized())		return 0; 	if (enabled) {		err = damon_sample_prcl_start();		if (err)			enabled = false;		return err;	}	damon_sample_prcl_stop();	return 0;} static int __init damon_sample_prcl_init(void){	int err = 0; 	if (!damon_initialized()) {		if (enabled)			enabled = false;		return -ENOMEM;	} 	if (enabled) {		err = damon_sample_prcl_start();		if (err)			enabled = false;	}	return 0;} module_init(damon_sample_prcl_init);