In f2fs_precache_extents(), For large files, It requires reading many
node blocks. Instead of reading each node block with synchronous I/O,
this patch applies readahead so that node blocks can be fetched in
advance.
It reduces the overhead of repeated sync reads and improves efficiency
when precaching extents of large files.
I created a file with the same largest extent and executed the test.
For this experiment, I set the file's largest extent with an offset of 0
and a size of 1GB. I configured the remaining area with 100MB extents.
5GB test file:
dd if=/dev/urandom of=test1 bs=1m count=5120
cp test1 test2
fsync test1
dd if=test1 of=test2 bs=1m skip=1024 seek=1024 count=100 conv=notrunc
dd if=test1 of=test2 bs=1m skip=1224 seek=1224 count=100 conv=notrunc
...
dd if=test1 of=test2 bs=1m skip=5024 seek=5024 count=100 conv=notrunc
reboot
I also created 10GB and 20GB files with large extents using the same
method.
ioctl(F2FS_IOC_PRECACHE_EXTENTS) test results are as follows:
+-----------+---------+---------+-----------+
| File size | Before | After | Reduction |
+-----------+---------+---------+-----------+
| 5GB | 101.8ms | 72.1ms | 29.2% |
| 10GB | 222.9ms | 149.5ms | 32.9% |
| 20GB | 446.2ms | 276.3ms | 38.1% |
+-----------+---------+---------+-----------+
Tested on a 256GB mobile device with an SM8750 chipset.
Reviewed-by: Sungjong Seo <sj1557....@samsung.com>
Reviewed-by: Sunmin Jeong <s_min.je...@samsung.com>
Signed-off-by: Yunji Kang <yunji0.k...@samsung.com>
---
v2:
- Modify the readahead condition check routine for better code
readability.
- Update the title from 'node block' to 'node blocks'.
fs/f2fs/data.c | 3 +++
fs/f2fs/f2fs.h | 1 +
fs/f2fs/node.c | 5 ++++-
3 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 7961e0ddfca3..ab3117e3b24a 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1572,6 +1572,9 @@ int f2fs_map_blocks(struct inode *inode, struct
f2fs_map_blocks *map, int flag)
pgofs = (pgoff_t)map->m_lblk;
end = pgofs + maxblocks;
+ if (flag == F2FS_GET_BLOCK_PRECACHE)
+ mode = LOOKUP_NODE_PRECACHE;
+
next_dnode:
if (map->m_may_create) {
if (f2fs_lfs_mode(sbi))
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 9d3bc9633c1d..3ce41528d48e 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -651,6 +651,7 @@ enum {
* look up a node with readahead called
* by get_data_block.
*/
+ LOOKUP_NODE_PRECACHE, /* look up a node for
F2FS_GET_BLOCK_PRECACHE */
};
#define DEFAULT_RETRY_IO_COUNT 8 /* maximum retry read IO or flush count
*/
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 4254db453b2d..d4bf3ce715c5 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -860,7 +860,10 @@ int f2fs_get_dnode_of_data(struct dnode_of_data *dn,
pgoff_t index, int mode)
set_nid(parent, offset[i - 1], nids[i], i == 1);
f2fs_alloc_nid_done(sbi, nids[i]);
done = true;
- } else if (mode == LOOKUP_NODE_RA && i == level && level > 1) {
+ } else if ((i == level && level > 1) &&
+ (mode == LOOKUP_NODE_RA ||
+ (mode == LOOKUP_NODE_PRECACHE &&
+ offset[i - 1] % MAX_RA_NODE == 0))) {
nfolio[i] = f2fs_get_node_folio_ra(parent, offset[i -
1]);
if (IS_ERR(nfolio[i])) {
err = PTR_ERR(nfolio[i]);
--
2.34.1
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