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Date: Wed, 27 Jan 2016 13:38:23 -0800
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao2.yu@...sung.com>
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] f2fs: remove vlist in extent node
Hi Chao,
Hmm. The original patch was just going under testing, and we couldn't post
them since there is a kernel panic issue.
This patch seems quite better approach, so I think we can integrate both of
the patches together.
So, how about this patch?
Hope you don't mind this.
Thanks,
>From a7844e0438db9ea9d12b7c0c40b655c3371bd6c9 Mon Sep 17 00:00:00 2001
From: Hou Pengyang <houpengyang@...wei.com>
Date: Tue, 26 Jan 2016 12:56:26 +0000
Subject: [PATCH] f2fs: improve shrink performance of extent nodes
On the worst case, we need to scan the whole radix tree and every rb-tree to
free the victimed extent_nodes when shrinking.
Pengyang initially introduced a victim_list to record the victimed extent_nodes,
and free these extent_nodes by just scanning a list.
Later, Chao Yu enhances the original patch to improve memory footprint by
removing victim list.
The policy of lru list shrinking becomes:
1) lock lru list's lock
2) trylock extent tree's lock
3) remove extent node from lru list
4) unlock lru list's lock
5) do shrink
6) repeat 1) to 5)
Signed-off-by: Hou Pengyang <houpengyang@...wei.com>
Signed-off-by: Chao Yu <chao2.yu@...sung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---
fs/f2fs/extent_cache.c | 87 +++++++++++++++++++++-----------------------------
fs/f2fs/f2fs.h | 1 +
2 files changed, 37 insertions(+), 51 deletions(-)
diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
index aae99f2..759b1b1 100644
--- a/fs/f2fs/extent_cache.c
+++ b/fs/f2fs/extent_cache.c
@@ -33,6 +33,7 @@ static struct extent_node *__attach_extent_node(struct f2fs_sb_info *sbi,
en->ei = *ei;
INIT_LIST_HEAD(&en->list);
+ en->et = et;
rb_link_node(&en->rb_node, parent, p);
rb_insert_color(&en->rb_node, &et->root);
@@ -63,8 +64,8 @@ static void __release_extent_node(struct f2fs_sb_info *sbi,
struct extent_tree *et, struct extent_node *en)
{
spin_lock(&sbi->extent_lock);
- if (!list_empty(&en->list))
- list_del_init(&en->list);
+ f2fs_bug_on(sbi, list_empty(&en->list));
+ list_del_init(&en->list);
spin_unlock(&sbi->extent_lock);
__detach_extent_node(sbi, et, en);
@@ -147,7 +148,7 @@ static struct extent_node *__init_extent_tree(struct f2fs_sb_info *sbi,
}
static unsigned int __free_extent_tree(struct f2fs_sb_info *sbi,
- struct extent_tree *et, bool free_all)
+ struct extent_tree *et)
{
struct rb_node *node, *next;
struct extent_node *en;
@@ -157,11 +158,7 @@ static unsigned int __free_extent_tree(struct f2fs_sb_info *sbi,
while (node) {
next = rb_next(node);
en = rb_entry(node, struct extent_node, rb_node);
-
- if (free_all)
- __release_extent_node(sbi, et, en);
- else if (list_empty(&en->list))
- __detach_extent_node(sbi, et, en);
+ __release_extent_node(sbi, et, en);
node = next;
}
@@ -532,7 +529,7 @@ static unsigned int f2fs_update_extent_tree_range(struct inode *inode,
}
if (is_inode_flag_set(F2FS_I(inode), FI_NO_EXTENT))
- __free_extent_tree(sbi, et, true);
+ __free_extent_tree(sbi, et);
write_unlock(&et->lock);
@@ -541,14 +538,10 @@ static unsigned int f2fs_update_extent_tree_range(struct inode *inode,
unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
{
- struct extent_tree *treevec[EXT_TREE_VEC_SIZE];
struct extent_tree *et, *next;
- struct extent_node *en, *tmp;
- unsigned long ino = F2FS_ROOT_INO(sbi);
- unsigned int found;
+ struct extent_node *en;
unsigned int node_cnt = 0, tree_cnt = 0;
int remained;
- bool do_free = false;
if (!test_opt(sbi, EXTENT_CACHE))
return 0;
@@ -561,11 +554,11 @@ unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
/* 1. remove unreferenced extent tree */
list_for_each_entry_safe(et, next, &sbi->zombie_list, list) {
- if (atomic_read(&et->node_cnt)) {
- write_lock(&et->lock);
- node_cnt += __free_extent_tree(sbi, et, true);
- write_unlock(&et->lock);
- }
+ write_lock(&et->lock);
+ node_cnt += __free_extent_tree(sbi, et);
+ write_unlock(&et->lock);
+ if (atomic_read(&et->node_cnt) > 0)
+ goto unlock_out;
list_del_init(&et->list);
radix_tree_delete(&sbi->extent_tree_root, et->ino);
@@ -587,42 +580,29 @@ free_node:
remained = nr_shrink - (node_cnt + tree_cnt);
spin_lock(&sbi->extent_lock);
- list_for_each_entry_safe(en, tmp, &sbi->extent_list, list) {
- if (!remained--)
+ for (; remained > 0; remained--) {
+ if (list_empty(&sbi->extent_list))
break;
- list_del_init(&en->list);
- do_free = true;
- }
- spin_unlock(&sbi->extent_lock);
-
- if (do_free == false)
- goto unlock_out;
-
- /*
- * reset ino for searching victims from beginning of global extent tree.
- */
- ino = F2FS_ROOT_INO(sbi);
-
- while ((found = radix_tree_gang_lookup(&sbi->extent_tree_root,
- (void **)treevec, ino, EXT_TREE_VEC_SIZE))) {
- unsigned i;
-
- ino = treevec[found - 1]->ino + 1;
- for (i = 0; i < found; i++) {
- struct extent_tree *et = treevec[i];
+ en = list_first_entry(&sbi->extent_list,
+ struct extent_node, list);
+ et = en->et;
+ if (!write_trylock(&et->lock)) {
+ /* refresh this extent node's position in extent list */
+ list_move_tail(&en->list, &sbi->extent_list);
+ continue;
+ }
- if (!atomic_read(&et->node_cnt))
- continue;
+ list_del_init(&en->list);
+ spin_unlock(&sbi->extent_lock);
- if (write_trylock(&et->lock)) {
- node_cnt += __free_extent_tree(sbi, et, false);
- write_unlock(&et->lock);
- }
+ __detach_extent_node(sbi, et, en);
- if (node_cnt + tree_cnt >= nr_shrink)
- goto unlock_out;
- }
+ write_unlock(&et->lock);
+ node_cnt++;
+ spin_lock(&sbi->extent_lock);
}
+ spin_unlock(&sbi->extent_lock);
+
unlock_out:
up_write(&sbi->extent_tree_lock);
out:
@@ -641,7 +621,7 @@ unsigned int f2fs_destroy_extent_node(struct inode *inode)
return 0;
write_lock(&et->lock);
- node_cnt = __free_extent_tree(sbi, et, true);
+ node_cnt = __free_extent_tree(sbi, et);
write_unlock(&et->lock);
return node_cnt;
@@ -666,10 +646,15 @@ void f2fs_destroy_extent_tree(struct inode *inode)
}
/* free all extent info belong to this extent tree */
+free_more:
node_cnt = f2fs_destroy_extent_node(inode);
/* delete extent tree entry in radix tree */
down_write(&sbi->extent_tree_lock);
+ if (atomic_read(&et->node_cnt) > 0) {
+ up_write(&sbi->extent_tree_lock);
+ goto free_more;
+ }
f2fs_bug_on(sbi, atomic_read(&et->node_cnt));
radix_tree_delete(&sbi->extent_tree_root, inode->i_ino);
kmem_cache_free(extent_tree_slab, et);
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index c4e723b..4e7eab9 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -354,6 +354,7 @@ struct extent_node {
struct rb_node rb_node; /* rb node located in rb-tree */
struct list_head list; /* node in global extent list of sbi */
struct extent_info ei; /* extent info */
+ struct extent_tree *et; /* extent tree pointer */
};
struct extent_tree {
--
2.6.3
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