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From: SeongJae Park <sjpark@amazon.com>
To: <akpm@linux-foundation.org>
Cc: SeongJae Park <sjpark@amazon.de>, <aarcange@redhat.com>,
	<acme@kernel.org>, <alexander.shishkin@linux.intel.com>,
	<amit@kernel.org>, <brendan.d.gregg@gmail.com>,
	<brendanhiggins@google.com>, <cai@lca.pw>,
	<colin.king@canonical.com>, <corbet@lwn.net>, <dwmw@amazon.com>,
	<jolsa@redhat.com>, <kirill@shutemov.name>,
	<mark.rutland@arm.com>, <mgorman@suse.de>, <minchan@kernel.org>,
	<mingo@redhat.com>, <namhyung@kernel.org>, <peterz@infradead.org>,
	<rdunlap@infradead.org>, <riel@surriel.com>,
	<rientjes@google.com>, <rostedt@goodmis.org>, <shuah@kernel.org>,
	<sj38.park@gmail.com>, <vbabka@suse.cz>, <vdavydov.dev@gmail.com>,
	<yang.shi@linux.alibaba.com>, <ying.huang@intel.com>,
	<linux-mm@kvack.org>, <linux-doc@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>
Subject: [RFC v4 4/7] mm/damon/schemes: Implement a debugfs interface
Date: Tue, 3 Mar 2020 13:14:03 +0100
Message-ID: <20200303121406.20954-5-sjpark@amazon.com> (raw)
In-Reply-To: <20200303121406.20954-1-sjpark@amazon.com>

From: SeongJae Park <sjpark@amazon.de>

This commit implements a debugfs interface for the data access
monitoring oriented memory management schemes.  It is supposed to be
used by administrators and/or privileged user space programs.  Users can
read and update the rules using ``<debugfs>/damon/schemes`` file.  The
format is::

    <min/max size> <min/max access frequency> <min/max age> <action>

Signed-off-by: SeongJae Park <sjpark@amazon.de>
---
 mm/damon.c | 171 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 169 insertions(+), 2 deletions(-)

diff --git a/mm/damon.c b/mm/damon.c
index 338e7ea76c7f..c573a0290234 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -199,6 +199,29 @@ static void damon_destroy_task(struct damon_task *t)
 	damon_free_task(t);
 }
 
+static struct damos *damon_new_scheme(
+		unsigned int min_sz_region, unsigned int max_sz_region,
+		unsigned int min_nr_accesses, unsigned int max_nr_accesses,
+		unsigned int min_age_region, unsigned int max_age_region,
+		enum damos_action action)
+{
+	struct damos *ret;
+
+	ret = kmalloc(sizeof(struct damos), GFP_KERNEL);
+	if (!ret)
+		return NULL;
+	ret->min_sz_region = min_sz_region;
+	ret->max_sz_region = max_sz_region;
+	ret->min_nr_accesses = min_nr_accesses;
+	ret->max_nr_accesses = max_nr_accesses;
+	ret->min_age_region = min_age_region;
+	ret->max_age_region = max_age_region;
+	ret->action = action;
+	INIT_LIST_HEAD(&ret->list);
+
+	return ret;
+}
+
 static void damon_add_scheme(struct damon_ctx *ctx, struct damos *s)
 {
 	list_add_tail(&s->list, &ctx->schemes_list);
@@ -1306,6 +1329,144 @@ static ssize_t debugfs_monitor_on_write(struct file *file,
 	return ret;
 }
 
+static ssize_t sprint_schemes(struct damon_ctx *c, char *buf, ssize_t len)
+{
+	struct damos *s;
+	int written = 0;
+	int rc;
+
+	damon_for_each_schemes(c, s) {
+		rc = snprintf(&buf[written], len - written,
+				"%u %u %u %u %u %u %d\n",
+				s->min_sz_region, s->max_sz_region,
+				s->min_nr_accesses, s->max_nr_accesses,
+				s->min_age_region, s->max_age_region,
+				s->action);
+		if (!rc)
+			return -ENOMEM;
+		written += rc;
+	}
+	return written;
+}
+
+static ssize_t debugfs_schemes_read(struct file *file, char __user *buf,
+		size_t count, loff_t *ppos)
+{
+	struct damon_ctx *ctx = &damon_user_ctx;
+	char *kbuf;
+	ssize_t ret;
+
+	kbuf = kmalloc(count, GFP_KERNEL);
+	if (!kbuf)
+		return -ENOMEM;
+
+	ret = sprint_schemes(ctx, kbuf, count);
+	if (ret < 0)
+		goto out;
+	ret = simple_read_from_buffer(buf, count, ppos, kbuf, ret);
+
+out:
+	kfree(kbuf);
+	return ret;
+}
+
+static void free_schemes_arr(struct damos **schemes, ssize_t nr_schemes)
+{
+	ssize_t i;
+
+	for (i = 0; i < nr_schemes; i++)
+		kfree(schemes[i]);
+	kfree(schemes);
+}
+
+/*
+ * Converts a string into an array of struct damos pointers
+ *
+ * Returns an array of struct damos pointers that converted if the conversion
+ * success, or NULL otherwise.
+ */
+static struct damos **str_to_schemes(const char *str, ssize_t len,
+				ssize_t *nr_schemes)
+{
+	struct damos *scheme, **schemes;
+	const int max_nr_schemes = 256;
+	int pos = 0, parsed, ret;
+	unsigned int min_sz, max_sz, min_nr_a, max_nr_a, min_age, max_age;
+	int action;
+
+	schemes = kmalloc_array(max_nr_schemes, sizeof(struct damos *),
+			GFP_KERNEL);
+	if (!schemes)
+		return NULL;
+
+	*nr_schemes = 0;
+	while (pos < len && *nr_schemes < max_nr_schemes) {
+		ret = sscanf(&str[pos], "%u %u %u %u %u %u %d%n",
+				&min_sz, &max_sz, &min_nr_a, &max_nr_a,
+				&min_age, &max_age, &action, &parsed);
+		pos += parsed;
+		if (ret != 7)
+			break;
+		if (action >= DAMOS_ACTION_LEN) {
+			pr_err("wrong action %d\n", action);
+			goto fail;
+		}
+
+		scheme = damon_new_scheme(min_sz, max_sz, min_nr_a, max_nr_a,
+				min_age, max_age, action);
+		if (!scheme)
+			goto fail;
+
+		schemes[*nr_schemes] = scheme;
+		*nr_schemes += 1;
+	}
+	if (!*nr_schemes)
+		goto fail;
+	return schemes;
+fail:
+	free_schemes_arr(schemes, *nr_schemes);
+	return NULL;
+}
+
+static ssize_t debugfs_schemes_write(struct file *file, const char __user *buf,
+		size_t count, loff_t *ppos)
+{
+	struct damon_ctx *ctx = &damon_user_ctx;
+	char *kbuf;
+	struct damos **schemes;
+	ssize_t nr_schemes = 0, ret;
+
+	if (*ppos)
+		return -EINVAL;
+
+	kbuf = kmalloc_array(count, sizeof(char), GFP_KERNEL);
+	if (!kbuf)
+		return -ENOMEM;
+
+	ret = simple_write_to_buffer(kbuf, count, ppos, buf, count);
+	if (ret < 0)
+		goto out;
+
+	schemes = str_to_schemes(kbuf, ret, &nr_schemes);
+
+	spin_lock(&ctx->kdamond_lock);
+	if (ctx->kdamond)
+		goto monitor_running;
+
+	damon_set_schemes(ctx, schemes, nr_schemes);
+	spin_unlock(&ctx->kdamond_lock);
+	goto out;
+
+monitor_running:
+	spin_unlock(&ctx->kdamond_lock);
+	pr_err("%s: kdamond is running. Turn it off first.\n", __func__);
+	ret = -EINVAL;
+	free_schemes_arr(schemes, nr_schemes);
+out:
+	kfree(kbuf);
+	return ret;
+}
+
 static ssize_t damon_sprint_pids(struct damon_ctx *ctx, char *buf, ssize_t len)
 {
 	struct damon_task *t;
@@ -1536,6 +1697,12 @@ static const struct file_operations pids_fops = {
 	.write = debugfs_pids_write,
 };
 
+static const struct file_operations schemes_fops = {
+	.owner = THIS_MODULE,
+	.read = debugfs_schemes_read,
+	.write = debugfs_schemes_write,
+};
+
 static const struct file_operations record_fops = {
 	.owner = THIS_MODULE,
 	.read = debugfs_record_read,
@@ -1552,10 +1719,10 @@ static struct dentry *debugfs_root;
 
 static int __init debugfs_init(void)
 {
-	const char * const file_names[] = {"attrs", "record",
+	const char * const file_names[] = {"attrs", "record", "schemes",
 		"pids", "monitor_on"};
 	const struct file_operations *fops[] = {&attrs_fops, &record_fops,
-		&pids_fops, &monitor_on_fops};
+		&schemes_fops, &pids_fops, &monitor_on_fops};
 	int i;
 
 	debugfs_root = debugfs_create_dir("damon", NULL);
-- 
2.17.1



  parent reply index

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-03 12:13 [RFC v4 0/7] Implement Data Access Monitoring-based Memory Operation Schemes SeongJae Park
2020-03-03 12:14 ` [RFC v4 1/7] mm/madvise: Export madvise_common() to mm internal code SeongJae Park
2020-03-03 12:14 ` [RFC v4 2/7] mm/damon: Account age of target regions SeongJae Park
2020-03-04 15:21   ` Rik van Riel
2020-03-04 16:07     ` SeongJae Park
2020-03-03 12:14 ` [RFC v4 3/7] mm/damon: Implement data access monitoring-based operation schemes SeongJae Park
2020-03-03 12:14 ` SeongJae Park [this message]
2020-03-03 12:14 ` [RFC v4 5/7] mm/damon-test: Add kunit test case for regions age accounting SeongJae Park
2020-03-03 12:14 ` [RFC v4 6/7] mm/damon/selftests: Add 'schemes' debugfs tests SeongJae Park
2020-03-03 12:14 ` [RFC v4 7/7] damon/tools: Support more human friendly 'schemes' control SeongJae Park

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