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Date: Mon, 12 Oct 2020 17:06:05 +0800
From: Chao Yu <yuchao0@...wei.com>
To: <jaegeuk@...nel.org>
CC: <linux-f2fs-devel@...ts.sourceforge.net>,
<linux-kernel@...r.kernel.org>, <chao@...nel.org>,
Chao Yu <yuchao0@...wei.com>
Subject: [PATCH] f2fs: introduce check_swap_activate_fast()
check_swap_activate() will lookup block mapping via bmap() one by one, so
its performance is very bad, this patch introduces check_swap_activate_fast()
to use f2fs_fiemap() to boost this process, since f2fs_fiemap() will lookup
block mappings in batch, therefore, it can improve swapon()'s performance
significantly.
Note that this enhancement only works when page size is equal to f2fs' block
size.
Testcase: (backend device: zram)
- touch file
- pin & fallocate file to 8GB
- mkswap file
- swapon file
Before:
real 0m2.999s
user 0m0.000s
sys 0m2.980s
After:
real 0m0.081s
user 0m0.000s
sys 0m0.064s
Signed-off-by: Chao Yu <yuchao0@...wei.com>
---
fs/f2fs/data.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 80 insertions(+)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index ee87407602fa..be4da52604ed 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -3883,6 +3883,83 @@ int f2fs_migrate_page(struct address_space *mapping,
#endif
#ifdef CONFIG_SWAP
+static int check_swap_activate_fast(struct swap_info_struct *sis,
+ struct file *swap_file, sector_t *span)
+{
+ struct address_space *mapping = swap_file->f_mapping;
+ struct inode *inode = mapping->host;
+ sector_t cur_lblock;
+ sector_t last_lblock;
+ sector_t pblock;
+ sector_t lowest_pblock = -1;
+ sector_t highest_pblock = 0;
+ int nr_extents = 0;
+ unsigned long nr_pblocks;
+ unsigned long len;
+ int ret;
+
+ /*
+ * Map all the blocks into the extent list. This code doesn't try
+ * to be very smart.
+ */
+ cur_lblock = 0;
+ last_lblock = logical_to_blk(inode, i_size_read(inode));
+ len = i_size_read(inode);
+
+ while (cur_lblock <= last_lblock && cur_lblock < sis->max) {
+ struct buffer_head map_bh;
+ pgoff_t next_pgofs;
+
+ cond_resched();
+
+ memset(&map_bh, 0, sizeof(struct buffer_head));
+ map_bh.b_size = len - cur_lblock;
+
+ ret = get_data_block(inode, cur_lblock, &map_bh, 0,
+ F2FS_GET_BLOCK_FIEMAP, &next_pgofs);
+ if (ret)
+ goto err_out;
+
+ /* hole */
+ if (!buffer_mapped(&map_bh))
+ goto err_out;
+
+ pblock = map_bh.b_blocknr;
+ nr_pblocks = logical_to_blk(inode, map_bh.b_size);
+
+ if (cur_lblock + nr_pblocks >= sis->max)
+ nr_pblocks = sis->max - cur_lblock;
+
+ if (cur_lblock) { /* exclude the header page */
+ if (pblock < lowest_pblock)
+ lowest_pblock = pblock;
+ if (pblock + nr_pblocks - 1 > highest_pblock)
+ highest_pblock = pblock + nr_pblocks - 1;
+ }
+
+ /*
+ * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
+ */
+ ret = add_swap_extent(sis, cur_lblock, nr_pblocks, pblock);
+ if (ret < 0)
+ goto out;
+ nr_extents += ret;
+ cur_lblock += nr_pblocks;
+ }
+ ret = nr_extents;
+ *span = 1 + highest_pblock - lowest_pblock;
+ if (cur_lblock == 0)
+ cur_lblock = 1; /* force Empty message */
+ sis->max = cur_lblock;
+ sis->pages = cur_lblock - 1;
+ sis->highest_bit = cur_lblock - 1;
+out:
+ return ret;
+err_out:
+ pr_err("swapon: swapfile has holes\n");
+ return -EINVAL;
+}
+
/* Copied from generic_swapfile_activate() to check any holes */
static int check_swap_activate(struct swap_info_struct *sis,
struct file *swap_file, sector_t *span)
@@ -3899,6 +3976,9 @@ static int check_swap_activate(struct swap_info_struct *sis,
int nr_extents = 0;
int ret;
+ if (PAGE_SIZE == F2FS_BLKSIZE)
+ return check_swap_activate_fast(sis, swap_file, span);
+
blkbits = inode->i_blkbits;
blocks_per_page = PAGE_SIZE >> blkbits;
--
2.26.2
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