]> www.infradead.org Git - users/jedix/linux-maple.git/commitdiff
mm: multi-gen LRU: debugfs interface
authorYu Zhao <yuzhao@google.com>
Thu, 14 Apr 2022 19:16:57 +0000 (12:16 -0700)
committerLiam R. Howlett <Liam.Howlett@oracle.com>
Thu, 14 Apr 2022 21:49:53 +0000 (17:49 -0400)
Add /sys/kernel/debug/lru_gen for working set estimation and proactive
reclaim.  These features are required to optimize job scheduling (bin
packing) in data centers [1][2].

Compared with the page table-based approach and the PFN-based approach,
e.g., mm/damon/[vp]addr.c, this lruvec-based approach has the following
advantages:

1. It offers better choices because it is aware of memcgs, NUMA nodes,
   shared mappings and unmapped page cache.
2. It is more scalable because it is O(nr_hot_pages), whereas the
   PFN-based approach is O(nr_total_pages).

Add /sys/kernel/debug/lru_gen_full for debugging.

[1] https://dl.acm.org/doi/10.1145/3297858.3304053
[2] https://dl.acm.org/doi/10.1145/3503222.3507731

Link: https://lkml.kernel.org/r/20220407031525.2368067-13-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Brian Geffon <bgeffon@google.com>
Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Acked-by: Steven Barrett <steven@liquorix.net>
Acked-by: Suleiman Souhlal <suleiman@google.com>
Tested-by: Daniel Byrne <djbyrne@mtu.edu>
Tested-by: Donald Carr <d@chaos-reins.com>
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru>
Tested-by: Shuang Zhai <szhai2@cs.rochester.edu>
Tested-by: Sofia Trinh <sofia.trinh@edi.works>
Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
include/linux/nodemask.h
mm/vmscan.c

index 567c3ddba2c4220680ebbde8f38421fb168ea876..90840c459abcc34fad8c6a27491ad669621a02d1 100644 (file)
@@ -486,6 +486,7 @@ static inline int num_node_state(enum node_states state)
 #define first_online_node      0
 #define first_memory_node      0
 #define next_online_node(nid)  (MAX_NUMNODES)
+#define next_memory_node(nid)  (MAX_NUMNODES)
 #define nr_node_ids            1U
 #define nr_online_nodes                1U
 
index 9327b2f63665c903cd77c589a9fda0627f7f9cca..d4a7d2bd276da5dd26d1569dd94bb7d6b9151a1e 100644 (file)
@@ -53,6 +53,7 @@
 #include <linux/pagewalk.h>
 #include <linux/shmem_fs.h>
 #include <linux/ctype.h>
+#include <linux/debugfs.h>
 
 #include <asm/tlbflush.h>
 #include <asm/div64.h>
@@ -5206,6 +5207,348 @@ static struct attribute_group lru_gen_attr_group = {
        .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 = kvmalloc(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 get_lruvec(memcg, 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));
+
+       kvfree(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 get_lruvec(memcg, nid);
+}
+
+static void lru_gen_seq_show_full(struct seq_file *m, struct lruvec *lruvec,
+                                 unsigned long max_seq, unsigned long *min_seq,
+                                 unsigned long seq)
+{
+       int i;
+       int type, tier;
+       int hist = lru_hist_from_seq(seq);
+       struct lru_gen_struct *lrugen = &lruvec->lrugen;
+
+       for (tier = 0; tier < MAX_NR_TIERS; tier++) {
+               seq_printf(m, "            %10d", tier);
+               for (type = 0; type < ANON_AND_FILE; type++) {
+                       unsigned long n[3] = {};
+
+                       if (seq == max_seq) {
+                               n[0] = READ_ONCE(lrugen->avg_refaulted[type][tier]);
+                               n[1] = READ_ONCE(lrugen->avg_total[type][tier]);
+
+                               seq_printf(m, " %10luR %10luT %10lu ", n[0], n[1], n[2]);
+                       } else if (seq == min_seq[type] || NR_HIST_GENS > 1) {
+                               n[0] = atomic_long_read(&lrugen->refaulted[hist][type][tier]);
+                               n[1] = atomic_long_read(&lrugen->evicted[hist][type][tier]);
+                               if (tier)
+                                       n[2] = READ_ONCE(lrugen->protected[hist][type][tier - 1]);
+
+                               seq_printf(m, " %10lur %10lue %10lup", n[0], n[1], n[2]);
+                       } else
+                               seq_puts(m, "          0           0           0 ");
+               }
+               seq_putc(m, '\n');
+       }
+
+       seq_puts(m, "                      ");
+       for (i = 0; i < NR_MM_STATS; i++) {
+               if (seq == max_seq && NR_HIST_GENS == 1)
+                       seq_printf(m, " %10lu%c", READ_ONCE(lruvec->mm_state.stats[hist][i]),
+                                  toupper(MM_STAT_CODES[i]));
+               else if (seq != max_seq && NR_HIST_GENS > 1)
+                       seq_printf(m, " %10lu%c", READ_ONCE(lruvec->mm_state.stats[hist][i]),
+                                  MM_STAT_CODES[i]);
+               else
+                       seq_puts(m, "          0 ");
+       }
+       seq_putc(m, '\n');
+}
+
+static int lru_gen_seq_show(struct seq_file *m, void *v)
+{
+       unsigned long seq;
+       bool full = !debugfs_real_fops(m->file)->write;
+       struct lruvec *lruvec = v;
+       struct lru_gen_struct *lrugen = &lruvec->lrugen;
+       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) {
+               const char *path = memcg ? m->private : "";
+
+#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), path);
+       }
+
+       seq_printf(m, " node %5d\n", nid);
+
+       if (!full)
+               seq = min_seq[LRU_GEN_ANON];
+       else if (max_seq >= MAX_NR_GENS)
+               seq = max_seq - MAX_NR_GENS + 1;
+       else
+               seq = 0;
+
+       for (; seq <= max_seq; seq++) {
+               int type, zone;
+               int gen = lru_gen_from_seq(seq);
+               unsigned long birth = READ_ONCE(lruvec->lrugen.timestamps[gen]);
+
+               seq_printf(m, " %10lu %10u", seq, jiffies_to_msecs(jiffies - birth));
+
+               for (type = 0; type < ANON_AND_FILE; type++) {
+                       long size = 0;
+                       char mark = full && seq < min_seq[type] ? 'x' : ' ';
+
+                       for (zone = 0; zone < MAX_NR_ZONES; zone++)
+                               size += READ_ONCE(lrugen->nr_pages[gen][type][zone]);
+
+                       seq_printf(m, " %10lu%c", max(size, 0L), mark);
+               }
+
+               seq_putc(m, '\n');
+
+               if (full)
+                       lru_gen_seq_show_full(m, lruvec, max_seq, min_seq, seq);
+       }
+
+       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 run_aging(struct lruvec *lruvec, unsigned long seq, struct scan_control *sc,
+                    bool can_swap, bool full_scan)
+{
+       DEFINE_MAX_SEQ(lruvec);
+
+       if (seq == max_seq)
+               try_to_inc_max_seq(lruvec, max_seq, sc, can_swap, full_scan);
+
+       return seq > max_seq ? -EINVAL : 0;
+}
+
+static int run_eviction(struct lruvec *lruvec, unsigned long seq, struct scan_control *sc,
+                       int swappiness, unsigned long nr_to_reclaim)
+{
+       struct blk_plug plug;
+       int err = -EINTR;
+       DEFINE_MAX_SEQ(lruvec);
+
+       if (seq + MIN_NR_GENS > max_seq)
+               return -EINVAL;
+
+       sc->nr_reclaimed = 0;
+
+       blk_start_plug(&plug);
+
+       while (!signal_pending(current)) {
+               DEFINE_MIN_SEQ(lruvec);
+
+               if (seq < min_seq[!swappiness] || sc->nr_reclaimed >= nr_to_reclaim ||
+                   !evict_folios(lruvec, sc, swappiness, NULL)) {
+                       err = 0;
+                       break;
+               }
+
+               cond_resched();
+       }
+
+       blk_finish_plug(&plug);
+
+       return err;
+}
+
+static int run_cmd(char cmd, int memcg_id, int nid, unsigned long seq,
+                  struct scan_control *sc, int swappiness, unsigned long opt)
+{
+       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 = get_lruvec(memcg, nid);
+
+       if (swappiness < 0)
+               swappiness = get_swappiness(lruvec, sc);
+       else if (swappiness > 200)
+               goto done;
+
+       switch (cmd) {
+       case '+':
+               err = run_aging(lruvec, seq, sc, swappiness, opt);
+               break;
+       case '-':
+               err = run_eviction(lruvec, seq, sc, swappiness, opt);
+               break;
+       }
+done:
+       mem_cgroup_put(memcg);
+
+       return err;
+}
+
+static ssize_t lru_gen_seq_write(struct file *file, const char __user *src,
+                                size_t len, loff_t *pos)
+{
+       void *buf;
+       char *cur, *next;
+       unsigned int flags;
+       int err = 0;
+       struct scan_control sc = {
+               .may_writepage = true,
+               .may_unmap = true,
+               .may_swap = true,
+               .reclaim_idx = MAX_NR_ZONES - 1,
+               .gfp_mask = GFP_KERNEL,
+       };
+
+       buf = kvmalloc(len + 1, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
+       if (copy_from_user(buf, src, len)) {
+               kvfree(buf);
+               return -EFAULT;
+       }
+
+       next = buf;
+       next[len] = '\0';
+
+       sc.reclaim_state.mm_walk = alloc_mm_walk();
+       if (!sc.reclaim_state.mm_walk) {
+               kvfree(buf);
+               return -ENOMEM;
+       }
+
+       set_task_reclaim_state(current, &sc.reclaim_state);
+       flags = memalloc_noreclaim_save();
+
+       while ((cur = strsep(&next, ",;\n"))) {
+               int n;
+               int end;
+               char cmd;
+               unsigned int memcg_id;
+               unsigned int nid;
+               unsigned long seq;
+               unsigned int swappiness = -1;
+               unsigned long opt = -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, &opt, &end);
+               if (n < 4 || cur[end]) {
+                       err = -EINVAL;
+                       break;
+               }
+
+               err = run_cmd(cmd, memcg_id, nid, seq, &sc, swappiness, opt);
+               if (err)
+                       break;
+       }
+
+       memalloc_noreclaim_restore(flags);
+       set_task_reclaim_state(current, NULL);
+
+       free_mm_walk(sc.reclaim_state.mm_walk);
+       kvfree(buf);
+
+       return err ? : len;
+}
+
+static int lru_gen_seq_open(struct inode *inode, struct file *file)
+{
+       return seq_open(file, &lru_gen_seq_ops);
+}
+
+static const struct file_operations lru_gen_rw_fops = {
+       .open = lru_gen_seq_open,
+       .read = seq_read,
+       .write = lru_gen_seq_write,
+       .llseek = seq_lseek,
+       .release = seq_release,
+};
+
+static const struct file_operations lru_gen_ro_fops = {
+       .open = lru_gen_seq_open,
+       .read = seq_read,
+       .llseek = seq_lseek,
+       .release = seq_release,
+};
+
 /******************************************************************************
  *                          initialization
  ******************************************************************************/
@@ -5264,6 +5607,9 @@ static int __init init_lru_gen(void)
        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_rw_fops);
+       debugfs_create_file("lru_gen_full", 0444, NULL, NULL, &lru_gen_ro_fops);
+
        return 0;
 };
 late_initcall(init_lru_gen);