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fuse: optimize writepages search
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Re-work fi->writepages, replacing list with rb-tree.  This improves
performance because kernel fuse iterates through fi->writepages for each
writeback page and typical number of entries is about 800 (for 100MB of
fuse writeback).

Before patch:

10240+0 records in
10240+0 records out
10737418240 bytes (11 GB) copied, 41.3473 s, 260 MB/s

 2  1      0 57445400  40416 6323676    0    0    33 374743 8633 19210  1  8 88  3  0

  29.86%  [kernel]               [k] _raw_spin_lock
  26.62%  [fuse]                 [k] fuse_page_is_writeback

After patch:

10240+0 records in
10240+0 records out
10737418240 bytes (11 GB) copied, 21.4954 s, 500 MB/s

 2  9      0 53676040  31744 10265984    0    0    64 854790 10956 48387  1  6 88  6  0

  23.55%  [kernel]             [k] copy_user_enhanced_fast_string
   9.87%  [kernel]             [k] __memcpy
   3.10%  [kernel]             [k] _raw_spin_lock

Signed-off-by: Maxim Patlasov <mpatlasov@virtuozzo.com>
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Maxim Patlasov authored and Miklos Szeredi committed May 19, 2020
1 parent 5ddd9ce commit 6b2fb79
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Showing 2 changed files with 50 additions and 14 deletions.
62 changes: 49 additions & 13 deletions fs/fuse/file.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -357,7 +357,7 @@ u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id)

struct fuse_writepage_args {
struct fuse_io_args ia;
struct list_head writepages_entry;
struct rb_node writepages_entry;
struct list_head queue_entry;
struct fuse_writepage_args *next;
struct inode *inode;
Expand All @@ -366,17 +366,23 @@ struct fuse_writepage_args {
static struct fuse_writepage_args *fuse_find_writeback(struct fuse_inode *fi,
pgoff_t idx_from, pgoff_t idx_to)
{
struct fuse_writepage_args *wpa;
struct rb_node *n;

n = fi->writepages.rb_node;

list_for_each_entry(wpa, &fi->writepages, writepages_entry) {
while (n) {
struct fuse_writepage_args *wpa;
pgoff_t curr_index;

wpa = rb_entry(n, struct fuse_writepage_args, writepages_entry);
WARN_ON(get_fuse_inode(wpa->inode) != fi);
curr_index = wpa->ia.write.in.offset >> PAGE_SHIFT;
if (idx_from < curr_index + wpa->ia.ap.num_pages &&
curr_index <= idx_to) {
if (idx_from >= curr_index + wpa->ia.ap.num_pages)
n = n->rb_right;
else if (idx_to < curr_index)
n = n->rb_left;
else
return wpa;
}
}
return NULL;
}
Expand Down Expand Up @@ -1624,7 +1630,7 @@ static void fuse_writepage_finish(struct fuse_conn *fc,
struct backing_dev_info *bdi = inode_to_bdi(inode);
int i;

list_del(&wpa->writepages_entry);
rb_erase(&wpa->writepages_entry, &fi->writepages);
for (i = 0; i < ap->num_pages; i++) {
dec_wb_stat(&bdi->wb, WB_WRITEBACK);
dec_node_page_state(ap->pages[i], NR_WRITEBACK_TEMP);
Expand Down Expand Up @@ -1712,6 +1718,36 @@ __acquires(fi->lock)
}
}

static void tree_insert(struct rb_root *root, struct fuse_writepage_args *wpa)
{
pgoff_t idx_from = wpa->ia.write.in.offset >> PAGE_SHIFT;
pgoff_t idx_to = idx_from + wpa->ia.ap.num_pages - 1;
struct rb_node **p = &root->rb_node;
struct rb_node *parent = NULL;

WARN_ON(!wpa->ia.ap.num_pages);
while (*p) {
struct fuse_writepage_args *curr;
pgoff_t curr_index;

parent = *p;
curr = rb_entry(parent, struct fuse_writepage_args,
writepages_entry);
WARN_ON(curr->inode != wpa->inode);
curr_index = curr->ia.write.in.offset >> PAGE_SHIFT;

if (idx_from >= curr_index + curr->ia.ap.num_pages)
p = &(*p)->rb_right;
else if (idx_to < curr_index)
p = &(*p)->rb_left;
else
return (void) WARN_ON(true);
}

rb_link_node(&wpa->writepages_entry, parent, p);
rb_insert_color(&wpa->writepages_entry, root);
}

static void fuse_writepage_end(struct fuse_conn *fc, struct fuse_args *args,
int error)
{
Expand All @@ -1730,7 +1766,7 @@ static void fuse_writepage_end(struct fuse_conn *fc, struct fuse_args *args,
wpa->next = next->next;
next->next = NULL;
next->ia.ff = fuse_file_get(wpa->ia.ff);
list_add(&next->writepages_entry, &fi->writepages);
tree_insert(&fi->writepages, next);

/*
* Skip fuse_flush_writepages() to make it easy to crop requests
Expand Down Expand Up @@ -1865,7 +1901,7 @@ static int fuse_writepage_locked(struct page *page)
inc_node_page_state(tmp_page, NR_WRITEBACK_TEMP);

spin_lock(&fi->lock);
list_add(&wpa->writepages_entry, &fi->writepages);
tree_insert(&fi->writepages, wpa);
list_add_tail(&wpa->queue_entry, &fi->queued_writes);
fuse_flush_writepages(inode);
spin_unlock(&fi->lock);
Expand Down Expand Up @@ -1977,10 +2013,10 @@ static bool fuse_writepage_in_flight(struct fuse_writepage_args *new_wpa,
WARN_ON(new_ap->num_pages != 0);

spin_lock(&fi->lock);
list_del(&new_wpa->writepages_entry);
rb_erase(&new_wpa->writepages_entry, &fi->writepages);
old_wpa = fuse_find_writeback(fi, page->index, page->index);
if (!old_wpa) {
list_add(&new_wpa->writepages_entry, &fi->writepages);
tree_insert(&fi->writepages, new_wpa);
spin_unlock(&fi->lock);
return false;
}
Expand Down Expand Up @@ -2095,7 +2131,7 @@ static int fuse_writepages_fill(struct page *page,
wpa->inode = inode;

spin_lock(&fi->lock);
list_add(&wpa->writepages_entry, &fi->writepages);
tree_insert(&fi->writepages, wpa);
spin_unlock(&fi->lock);

data->wpa = wpa;
Expand Down Expand Up @@ -3405,5 +3441,5 @@ void fuse_init_file_inode(struct inode *inode)
INIT_LIST_HEAD(&fi->queued_writes);
fi->writectr = 0;
init_waitqueue_head(&fi->page_waitq);
INIT_LIST_HEAD(&fi->writepages);
fi->writepages = RB_ROOT;
}
2 changes: 1 addition & 1 deletion fs/fuse/fuse_i.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -111,7 +111,7 @@ struct fuse_inode {
wait_queue_head_t page_waitq;

/* List of writepage requestst (pending or sent) */
struct list_head writepages;
struct rb_root writepages;
};

/* readdir cache (directory only) */
Expand Down

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