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Message-ID: <20200616073828.16509-5-sjpark@amazon.com>
Date: Tue, 16 Jun 2020 09:38:24 +0200
From: SeongJae Park <sjpark@...zon.com>
To: <akpm@...ux-foundation.org>
CC: SeongJae Park <sjpark@...zon.de>, <Jonathan.Cameron@...wei.com>,
<aarcange@...hat.com>, <acme@...nel.org>,
<alexander.shishkin@...ux.intel.com>, <amit@...nel.org>,
<benh@...nel.crashing.org>, <brendan.d.gregg@...il.com>,
<brendanhiggins@...gle.com>, <cai@....pw>,
<colin.king@...onical.com>, <corbet@....net>, <dwmw@...zon.com>,
<foersleo@...zon.de>, <irogers@...gle.com>, <jolsa@...hat.com>,
<kirill@...temov.name>, <mark.rutland@....com>, <mgorman@...e.de>,
<minchan@...nel.org>, <mingo@...hat.com>, <namhyung@...nel.org>,
<peterz@...radead.org>, <rdunlap@...radead.org>,
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<sj38.park@...il.com>, <snu@...zon.de>, <vbabka@...e.cz>,
<vdavydov.dev@...il.com>, <yang.shi@...ux.alibaba.com>,
<ying.huang@...el.com>, <david@...hat.com>,
<linux-damon@...zon.com>, <linux-mm@...ck.org>,
<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [RFC v12 4/8] mm/damon/schemes: Implement a debugfs interface
From: SeongJae Park <sjpark@...zon.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@...zon.de>
---
mm/damon.c | 171 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 169 insertions(+), 2 deletions(-)
diff --git a/mm/damon.c b/mm/damon.c
index 53d30abee6b7..f3805e2a7534 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -193,6 +193,29 @@ 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 *scheme;
+
+ scheme = kmalloc(sizeof(*scheme), GFP_KERNEL);
+ if (!scheme)
+ return NULL;
+ scheme->min_sz_region = min_sz_region;
+ scheme->max_sz_region = max_sz_region;
+ scheme->min_nr_accesses = min_nr_accesses;
+ scheme->max_nr_accesses = max_nr_accesses;
+ scheme->min_age_region = min_age_region;
+ scheme->max_age_region = max_age_region;
+ scheme->action = action;
+ INIT_LIST_HEAD(&scheme->list);
+
+ return scheme;
+}
+
static void damon_add_scheme(struct damon_ctx *ctx, struct damos *s)
{
list_add_tail(&s->list, &ctx->schemes_list);
@@ -1468,6 +1491,144 @@ 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_scheme(s, c) {
+ 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 len;
+
+ kbuf = kmalloc(count, GFP_KERNEL);
+ if (!kbuf)
+ return -ENOMEM;
+
+ mutex_lock(&ctx->kdamond_lock);
+ len = sprint_schemes(ctx, kbuf, count);
+ mutex_unlock(&ctx->kdamond_lock);
+ if (len < 0)
+ goto out;
+ len = simple_read_from_buffer(buf, count, ppos, kbuf, len);
+
+out:
+ kfree(kbuf);
+ return len;
+}
+
+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;
+ unsigned int action;
+
+ schemes = kmalloc_array(max_nr_schemes, sizeof(scheme),
+ 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 %u%n",
+ &min_sz, &max_sz, &min_nr_a, &max_nr_a,
+ &min_age, &max_age, &action, &parsed);
+ if (ret != 7)
+ break;
+ if (action >= DAMOS_ACTION_LEN) {
+ pr_err("wrong action %d\n", action);
+ goto fail;
+ }
+
+ pos += parsed;
+ 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;
+ }
+ 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 = count;
+ int err;
+
+ kbuf = user_input_str(buf, count, ppos);
+ if (IS_ERR(kbuf))
+ return PTR_ERR(kbuf);
+
+ schemes = str_to_schemes(kbuf, ret, &nr_schemes);
+ if (!schemes) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ mutex_lock(&ctx->kdamond_lock);
+ if (ctx->kdamond) {
+ ret = -EBUSY;
+ goto unlock_out;
+ }
+
+ err = damon_set_schemes(ctx, schemes, nr_schemes);
+ if (err)
+ ret = err;
+ else
+ nr_schemes = 0;
+unlock_out:
+ mutex_unlock(&ctx->kdamond_lock);
+ 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;
@@ -1686,6 +1847,12 @@ 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,
@@ -1702,10 +1869,10 @@ static struct dentry *debugfs_root;
static int __init damon_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
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