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Date: Thu, 20 Aug 2020 18:55:20 -0700
From: Harshad Shirwadkar <harshadshirwadkar@...il.com>
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu, lyx1209@...il.com,
Harshad Shirwadkar <harshadshirwadkar@...il.com>
Subject: [RFC PATCH v2 6/9] ext4: add memory usage tracker for freespace trees
From: Harshad Shirwadkar <harshadshirwadkar@...il.com>
Freespace trees can occupy a lot of memory with as the fragmentation
increases. This patch adds a sysfs file to monitor the memory usage of
the freespace tree allocator. Also, added a sysfs config to control
maximum memory that the allocator can use. If the allocator exceeds
this threshold, file system enters "FRSP_MEM_CRUNCH" state. The next
patch in the series performs LRU eviction when this state is reached.
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@...il.com>
---
fs/ext4/ext4.h | 8 ++++++++
fs/ext4/mballoc.c | 20 ++++++++++++++++++++
fs/ext4/mballoc.h | 4 ++++
fs/ext4/sysfs.c | 11 +++++++++++
4 files changed, 43 insertions(+)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 15e6ce9f1afa..93bf2fe35cf1 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1223,6 +1223,12 @@ struct ext4_inode_info {
* allocator off)
*/
+#define EXT4_MOUNT2_FRSP_MEM_CRUNCH 0x00000040 /*
+ * Freespace tree allocator
+ * is in a tight memory
+ * situation.
+ */
+
#define clear_opt(sb, opt) EXT4_SB(sb)->s_mount_opt &= \
~EXT4_MOUNT_##opt
#define set_opt(sb, opt) EXT4_SB(sb)->s_mount_opt |= \
@@ -1607,6 +1613,8 @@ struct ext4_sb_info {
atomic_t s_mb_num_frsp_trees_cached;
struct list_head s_mb_uncached_trees;
u32 s_mb_frsp_cache_aggression;
+ atomic_t s_mb_num_fragments;
+ u32 s_mb_frsp_mem_limit;
/* workqueue for reserved extent conversions (buffered io) */
struct workqueue_struct *rsv_conversion_wq;
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 1da63afdbb3d..b28b7fb0506e 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -869,6 +869,7 @@ void ext4_mb_frsp_print_tree_len(struct super_block *sb,
static struct ext4_frsp_node *ext4_mb_frsp_alloc_node(struct super_block *sb)
{
struct ext4_frsp_node *node;
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
node = kmem_cache_alloc(ext4_freespace_node_cachep, GFP_NOFS);
if (!node)
@@ -877,13 +878,31 @@ static struct ext4_frsp_node *ext4_mb_frsp_alloc_node(struct super_block *sb)
RB_CLEAR_NODE(&node->frsp_node);
RB_CLEAR_NODE(&node->frsp_len_node);
+ atomic_inc(&sbi->s_mb_num_fragments);
+
+ if (sbi->s_mb_frsp_mem_limit &&
+ atomic_read(&sbi->s_mb_num_fragments) >
+ EXT4_FRSP_MEM_LIMIT_TO_NUM_NODES(sb))
+ set_opt2(sb, FRSP_MEM_CRUNCH);
+ else
+ clear_opt2(sb, FRSP_MEM_CRUNCH);
+
+
return node;
}
static void ext4_mb_frsp_free_node(struct super_block *sb,
struct ext4_frsp_node *node)
{
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+
kmem_cache_free(ext4_freespace_node_cachep, node);
+ atomic_dec(&sbi->s_mb_num_fragments);
+
+ if (!sbi->s_mb_frsp_mem_limit ||
+ atomic_read(&sbi->s_mb_num_fragments) <
+ EXT4_FRSP_MEM_LIMIT_TO_NUM_NODES(sb))
+ clear_opt2(sb, FRSP_MEM_CRUNCH);
}
/* Evict a tree from memory */
@@ -1607,6 +1626,7 @@ int ext4_mb_init_freespace_trees(struct super_block *sb)
}
rwlock_init(&sbi->s_mb_frsp_lock);
atomic_set(&sbi->s_mb_num_frsp_trees_cached, 0);
+ atomic_set(&sbi->s_mb_num_fragments, 0);
return 0;
}
diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
index 1fcdd3e6f7d5..6cfb228e4da2 100644
--- a/fs/ext4/mballoc.h
+++ b/fs/ext4/mballoc.h
@@ -92,6 +92,10 @@ struct ext4_frsp_node {
struct rb_node frsp_node;
struct rb_node frsp_len_node;
};
+
+#define EXT4_FRSP_MEM_LIMIT_TO_NUM_NODES(__sb) \
+ ((sbi->s_mb_frsp_mem_limit / sizeof(struct ext4_frsp_node)))
+
struct ext4_free_data {
/* this links the free block information from sb_info */
struct list_head efd_list;
diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
index bfabb799fa45..19301b10944b 100644
--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -8,6 +8,7 @@
*
*/
+#include "mballoc.h"
#include <linux/time.h>
#include <linux/fs.h>
#include <linux/seq_file.h>
@@ -24,6 +25,7 @@ typedef enum {
attr_session_write_kbytes,
attr_lifetime_write_kbytes,
attr_reserved_clusters,
+ attr_frsp_tree_usage,
attr_inode_readahead,
attr_trigger_test_error,
attr_first_error_time,
@@ -208,6 +210,7 @@ EXT4_ATTR_FUNC(delayed_allocation_blocks, 0444);
EXT4_ATTR_FUNC(session_write_kbytes, 0444);
EXT4_ATTR_FUNC(lifetime_write_kbytes, 0444);
EXT4_ATTR_FUNC(reserved_clusters, 0644);
+EXT4_ATTR_FUNC(frsp_tree_usage, 0444);
EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, inode_readahead,
ext4_sb_info, s_inode_readahead_blks);
@@ -248,6 +251,7 @@ EXT4_ATTR(last_error_time, 0444, last_error_time);
EXT4_ATTR(journal_task, 0444, journal_task);
EXT4_RW_ATTR_SBI_UI(mb_prefetch, s_mb_prefetch);
EXT4_RW_ATTR_SBI_UI(mb_prefetch_limit, s_mb_prefetch_limit);
+EXT4_RW_ATTR_SBI_UI(mb_frsp_max_mem, s_mb_frsp_mem_limit);
static unsigned int old_bump_val = 128;
EXT4_ATTR_PTR(max_writeback_mb_bump, 0444, pointer_ui, &old_bump_val);
@@ -257,6 +261,7 @@ static struct attribute *ext4_attrs[] = {
ATTR_LIST(session_write_kbytes),
ATTR_LIST(lifetime_write_kbytes),
ATTR_LIST(reserved_clusters),
+ ATTR_LIST(frsp_tree_usage),
ATTR_LIST(inode_readahead_blks),
ATTR_LIST(inode_goal),
ATTR_LIST(mb_stats),
@@ -296,6 +301,7 @@ static struct attribute *ext4_attrs[] = {
#endif
ATTR_LIST(mb_prefetch),
ATTR_LIST(mb_prefetch_limit),
+ ATTR_LIST(mb_frsp_max_mem),
NULL,
};
ATTRIBUTE_GROUPS(ext4);
@@ -378,6 +384,11 @@ static ssize_t ext4_attr_show(struct kobject *kobj,
return snprintf(buf, PAGE_SIZE, "%llu\n",
(unsigned long long)
atomic64_read(&sbi->s_resv_clusters));
+ case attr_frsp_tree_usage:
+ return snprintf(buf, PAGE_SIZE, "%llu\n",
+ (unsigned long long)
+ atomic_read(&sbi->s_mb_num_fragments) *
+ sizeof(struct ext4_frsp_node));
case attr_inode_readahead:
case attr_pointer_ui:
if (!ptr)
--
2.28.0.297.g1956fa8f8d-goog
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