Add a sysfs file /sys/kernel/mm/lru_gen/enabled so user space can
enable and disable multigenerational lru at runtime.
Add a sysfs file /sys/kernel/mm/lru_gen/spread so user space can
spread pages out across multiple generations. More generations make
the background aging more aggressive.
Add a debugfs file /sys/kernel/debug/lru_gen so user space can monitor
multigenerational lru and trigger the aging and the eviction. This
file has the following output:
memcg memcg_id memcg_path
node node_id
min_gen birth_time anon_size file_size
...
max_gen birth_time anon_size file_size
Given a memcg and a node, "min_gen" is the oldest generation (number)
and "max_gen" is the youngest. Birth time is in milliseconds. Anon and
file sizes are in pages.
Write "+ memcg_id node_id gen [swappiness]" to this file to account
referenced pages to generation "max_gen" and create next generation
"max_gen"+1. "gen" must be equal to "max_gen" in order to avoid races.
A swap file and a non-zero swappiness value are required to scan anon
pages. If swapping is not desired, set vm.swappiness to 0 and
overwrite it with a non-zero "swappiness".
Write "- memcg_id node_id gen [swappiness] [nr_to_reclaim]" to this
file to evict generations less than or equal to "gen". "gen" must be
less than "max_gen"-1 as "max_gen" and "max_gen"-1 are active
generations and therefore protected from the eviction. "nr_to_reclaim"
can be used to limit the number of pages to be evicted.
Multiple command lines are supported, so does concatenation with
delimiters "," and ";".
Signed-off-by: Yu Zhao <yuz...@google.com>
---
mm/vmscan.c | 334 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 334 insertions(+)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index ce868d89dc53..b59b556e9587 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -51,6 +51,7 @@
#include <linux/psi.h>
#include <linux/pagewalk.h>
#include <linux/memory.h>
+#include <linux/debugfs.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
@@ -5833,6 +5834,334 @@ lru_gen_online_mem(struct notifier_block *self,
unsigned long action, void *arg)
return NOTIFY_DONE;
}
+/******************************************************************************
+ * sysfs interface
+
******************************************************************************/
+
+static ssize_t show_lru_gen_spread(struct kobject *kobj, struct kobj_attribute
*attr,
+ char *buf)
+{
+ return sprintf(buf, "%d\n", READ_ONCE(lru_gen_spread));
+}
+
+static ssize_t store_lru_gen_spread(struct kobject *kobj, struct
kobj_attribute *attr,
+ const char *buf, size_t len)
+{
+ int spread;
+
+ if (kstrtoint(buf, 10, &spread) || spread >= MAX_NR_GENS)
+ return -EINVAL;
+
+ WRITE_ONCE(lru_gen_spread, spread);
+
+ return len;
+}
+
+static struct kobj_attribute lru_gen_spread_attr = __ATTR(
+ spread, 0644,
+ show_lru_gen_spread, store_lru_gen_spread
+);
+
+static ssize_t show_lru_gen_enabled(struct kobject *kobj, struct
kobj_attribute *attr,
+ char *buf)
+{
+ return snprintf(buf, PAGE_SIZE, "%ld\n", lru_gen_enabled());
+}
+
+static ssize_t store_lru_gen_enabled(struct kobject *kobj, struct
kobj_attribute *attr,
+ const char *buf, size_t len)
+{
+ int enable;
+
+ if (kstrtoint(buf, 10, &enable))
+ return -EINVAL;
+
+ lru_gen_set_state(enable, true, false);
+
+ return len;
+}
+
+static struct kobj_attribute lru_gen_enabled_attr = __ATTR(
+ enabled, 0644, show_lru_gen_enabled, store_lru_gen_enabled
+);
+
+static struct attribute *lru_gen_attrs[] = {
+ &lru_gen_spread_attr.attr,
+ &lru_gen_enabled_attr.attr,
+ NULL
+};
+
+static struct attribute_group lru_gen_attr_group = {
+ .name = "lru_gen",
+ .attrs = lru_gen_attrs,
+};
+
+/******************************************************************************
+ * debugfs interface
+
******************************************************************************/
+
+static void *lru_gen_seq_start(struct seq_file *m, loff_t *pos)
+{
+ struct mem_cgroup *memcg;
+ loff_t nr_to_skip = *pos;
+
+ m->private = kzalloc(PATH_MAX, GFP_KERNEL);
+ if (!m->private)
+ return ERR_PTR(-ENOMEM);
+
+ memcg = mem_cgroup_iter(NULL, NULL, NULL);
+ do {
+ int nid;
+
+ for_each_node_state(nid, N_MEMORY) {
+ if (!nr_to_skip--)
+ return mem_cgroup_lruvec(memcg, NODE_DATA(nid));
+ }
+ } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)));
+
+ return NULL;
+}
+
+static void lru_gen_seq_stop(struct seq_file *m, void *v)
+{
+ if (!IS_ERR_OR_NULL(v))
+ mem_cgroup_iter_break(NULL, lruvec_memcg(v));
+
+ kfree(m->private);
+ m->private = NULL;
+}
+
+static void *lru_gen_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ int nid = lruvec_pgdat(v)->node_id;
+ struct mem_cgroup *memcg = lruvec_memcg(v);
+
+ ++*pos;
+
+ nid = next_memory_node(nid);
+ if (nid == MAX_NUMNODES) {
+ memcg = mem_cgroup_iter(NULL, memcg, NULL);
+ if (!memcg)
+ return NULL;
+
+ nid = first_memory_node;
+ }
+
+ return mem_cgroup_lruvec(memcg, NODE_DATA(nid));
+}
+
+static int lru_gen_seq_show(struct seq_file *m, void *v)
+{
+ unsigned long seq;
+ struct lruvec *lruvec = v;
+ int nid = lruvec_pgdat(lruvec)->node_id;
+ struct mem_cgroup *memcg = lruvec_memcg(lruvec);
+ DEFINE_MAX_SEQ(lruvec);
+ DEFINE_MIN_SEQ(lruvec);
+
+ if (nid == first_memory_node) {
+#ifdef CONFIG_MEMCG
+ if (memcg)
+ cgroup_path(memcg->css.cgroup, m->private, PATH_MAX);
+#endif
+ seq_printf(m, "memcg %5hu %s\n",
+ mem_cgroup_id(memcg), (char *)m->private);
+ }
+
+ seq_printf(m, " node %4d\n", nid);
+
+ for (seq = min(min_seq[0], min_seq[1]); seq <= max_seq; seq++) {
+ int gen, file, zone;
+ unsigned int msecs;
+ long sizes[ANON_AND_FILE] = {};
+
+ gen = lru_gen_from_seq(seq);
+
+ msecs = jiffies_to_msecs(jiffies - READ_ONCE(
+ lruvec->evictable.timestamps[gen]));
+
+ for_each_type_zone(file, zone)
+ sizes[file] += READ_ONCE(
+ lruvec->evictable.sizes[gen][file][zone]);
+
+ sizes[0] = max(sizes[0], 0L);
+ sizes[1] = max(sizes[1], 0L);
+
+ seq_printf(m, "%11lu %9u %9lu %9lu\n",
+ seq, msecs, sizes[0], sizes[1]);
+ }
+
+ return 0;
+}
+
+static const struct seq_operations lru_gen_seq_ops = {
+ .start = lru_gen_seq_start,
+ .stop = lru_gen_seq_stop,
+ .next = lru_gen_seq_next,
+ .show = lru_gen_seq_show,
+};
+
+static int lru_gen_debugfs_open(struct inode *inode, struct file *file)
+{
+ return seq_open(file, &lru_gen_seq_ops);
+}
+
+static int advance_max_seq(struct lruvec *lruvec, unsigned long seq, int
swappiness)
+{
+ struct scan_control sc = {
+ .target_mem_cgroup = lruvec_memcg(lruvec),
+ };
+ DEFINE_MAX_SEQ(lruvec);
+
+ if (seq == max_seq)
+ walk_mm_list(lruvec, max_seq, &sc, swappiness);
+
+ return seq > max_seq ? -EINVAL : 0;
+}
+
+static int advance_min_seq(struct lruvec *lruvec, unsigned long seq, int
swappiness,
+ unsigned long nr_to_reclaim)
+{
+ struct blk_plug plug;
+ int err = -EINTR;
+ long nr_to_scan = LONG_MAX;
+ struct scan_control sc = {
+ .nr_to_reclaim = nr_to_reclaim,
+ .target_mem_cgroup = lruvec_memcg(lruvec),
+ .may_writepage = 1,
+ .may_unmap = 1,
+ .may_swap = 1,
+ .reclaim_idx = MAX_NR_ZONES - 1,
+ .gfp_mask = GFP_KERNEL,
+ };
+ DEFINE_MAX_SEQ(lruvec);
+
+ if (seq >= max_seq - 1)
+ return -EINVAL;
+
+ blk_start_plug(&plug);
+
+ while (!signal_pending(current)) {
+ DEFINE_MIN_SEQ(lruvec);
+
+ if (seq < min(min_seq[!swappiness], min_seq[swappiness < 200])
||
+ !evict_lru_gen_pages(lruvec, &sc, swappiness, &nr_to_scan))
{
+ err = 0;
+ break;
+ }
+
+ cond_resched();
+ }
+
+ blk_finish_plug(&plug);
+
+ return err;
+}
+
+static int advance_seq(char cmd, int memcg_id, int nid, unsigned long seq,
+ int swappiness, unsigned long nr_to_reclaim)
+{
+ struct lruvec *lruvec;
+ int err = -EINVAL;
+ struct mem_cgroup *memcg = NULL;
+
+ if (!mem_cgroup_disabled()) {
+ rcu_read_lock();
+ memcg = mem_cgroup_from_id(memcg_id);
+#ifdef CONFIG_MEMCG
+ if (memcg && !css_tryget(&memcg->css))
+ memcg = NULL;
+#endif
+ rcu_read_unlock();
+
+ if (!memcg)
+ goto done;
+ }
+ if (memcg_id != mem_cgroup_id(memcg))
+ goto done;
+
+ if (nid < 0 || nid >= MAX_NUMNODES || !node_state(nid, N_MEMORY))
+ goto done;
+
+ lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
+
+ if (swappiness == -1)
+ swappiness = get_swappiness(lruvec);
+ else if (swappiness > 200U)
+ goto done;
+
+ switch (cmd) {
+ case '+':
+ err = advance_max_seq(lruvec, seq, swappiness);
+ break;
+ case '-':
+ err = advance_min_seq(lruvec, seq, swappiness, nr_to_reclaim);
+ break;
+ }
+done:
+ mem_cgroup_put(memcg);
+
+ return err;
+}
+
+static ssize_t lru_gen_debugfs_write(struct file *file, const char __user *src,
+ size_t len, loff_t *pos)
+{
+ void *buf;
+ char *cur, *next;
+ int err = 0;
+
+ buf = kvmalloc(len + 1, GFP_USER);
+ if (!buf)
+ return -ENOMEM;
+
+ if (copy_from_user(buf, src, len)) {
+ kvfree(buf);
+ return -EFAULT;
+ }
+
+ next = buf;
+ next[len] = '\0';
+
+ while ((cur = strsep(&next, ",;\n"))) {
+ int n;
+ int end;
+ char cmd;
+ int memcg_id;
+ int nid;
+ unsigned long seq;
+ int swappiness = -1;
+ unsigned long nr_to_reclaim = -1;
+
+ cur = skip_spaces(cur);
+ if (!*cur)
+ continue;
+
+ n = sscanf(cur, "%c %u %u %lu %n %u %n %lu %n", &cmd,
&memcg_id, &nid,
+ &seq, &end, &swappiness, &end, &nr_to_reclaim, &end);
+ if (n < 4 || cur[end]) {
+ err = -EINVAL;
+ break;
+ }
+
+ err = advance_seq(cmd, memcg_id, nid, seq, swappiness,
nr_to_reclaim);
+ if (err)
+ break;
+ }
+
+ kvfree(buf);
+
+ return err ? : len;
+}
+
+static const struct file_operations lru_gen_debugfs_ops = {
+ .open = lru_gen_debugfs_open,
+ .read = seq_read,
+ .write = lru_gen_debugfs_write,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
/******************************************************************************
* initialization
******************************************************************************/
@@ -5873,6 +6202,11 @@ static int __init init_lru_gen(void)
if (hotplug_memory_notifier(lru_gen_online_mem, 0))
pr_err("lru_gen: failed to subscribe hotplug notifications\n");
+ if (sysfs_create_group(mm_kobj, &lru_gen_attr_group))
+ pr_err("lru_gen: failed to create sysfs group\n");
+
+ debugfs_create_file("lru_gen", 0644, NULL, NULL, &lru_gen_debugfs_ops);
+
return 0;
};
/*
--
2.31.0.rc2.261.g7f71774620-goog
