linux-toradex.git/fs/f2fs/gc.h, branch v4.4.72

f2fs: support synchronous gc in ioctl

2015-10-09T23:20:56+00:00

This patch drops in batches gc triggered through ioctl, since user
can easily control the gc by designing the loop around the ->ioctl.

We support synchronous gc by forcing using FG_GC in f2fs_gc, so with
it, user can make sure that in this round all blocks gced were
persistent in the device until ioctl returned.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: add new ioctl F2FS_IOC_GARBAGE_COLLECT

2015-08-04T21:09:58+00:00

When background gc is off, the only way to trigger gc is executing
a force gc in some operations who wants to grab space in disk.

The executing condition is limited: to execute force gc, we should
wait for the time when there is almost no more free section for LFS
allocation. This seems not reasonable for our user who wants to
control triggering gc by himself.

This patch introduces F2FS_IOC_GARBAGE_COLLECT interface for
triggering garbage collection by using ioctl. It provides our users
one more option to trigger gc.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: fix sparse warnings

2015-02-12T01:04:49+00:00

This patch resolves the following warnings.

include/trace/events/f2fs.h:150:1: warning: expression using sizeof bool
include/trace/events/f2fs.h:180:1: warning: expression using sizeof bool
include/trace/events/f2fs.h:990:1: warning: expression using sizeof bool
include/trace/events/f2fs.h:990:1: warning: expression using sizeof bool
include/trace/events/f2fs.h:150:1: warning: odd constant _Bool cast (ffffffffffffffff becomes 1)
include/trace/events/f2fs.h:180:1: warning: odd constant _Bool cast (ffffffffffffffff becomes 1)
include/trace/events/f2fs.h:990:1: warning: odd constant _Bool cast (ffffffffffffffff becomes 1)
include/trace/events/f2fs.h:990:1: warning: odd constant _Bool cast (ffffffffffffffff becomes 1)

fs/f2fs/checkpoint.c:27:19: warning: symbol 'inode_entry_slab' was not declared. Should it be static?
fs/f2fs/checkpoint.c:577:15: warning: cast to restricted __le32
fs/f2fs/checkpoint.c:592:15: warning: cast to restricted __le32

fs/f2fs/trace.c:19:1: warning: symbol 'pids' was not declared. Should it be static?
fs/f2fs/trace.c:21:21: warning: symbol 'last_io' was not declared. Should it be static?

Signed-off-by: Jaegeuk Kim

f2fs: clean up {in,de}create_sleep_time

2015-02-12T01:04:37+00:00

Use pointer parameter @wait to pass result in {in,de}create_sleep_time for
cleanup.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: reuse inode_entry_slab in gc procedure for using slab more effectively

2015-01-10T01:02:26+00:00

There are two slab cache inode_entry_slab and winode_slab using the same
structure as below:

struct dir_inode_entry {
	struct list_head list;	/* list head */
	struct inode *inode;	/* vfs inode pointer */
};

struct inode_entry {
	struct list_head list;
	struct inode *inode;
};

It's a little waste that the two cache can not share their memory space for each
other.
So in this patch we remove one redundant winode_slab slab cache, then use more
universal name struct inode_entry as remaining data structure name of slab,
finally we reuse the inode_entry_slab to store dirty dir item and gc item for
more effective.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: more fast lookup for gc_inode list

2014-12-02T19:02:50+00:00

If there are many inodes that have data blocks in victim segment,
it takes long time to find a inode in gc_inode list.
Let's use radix_tree to reduce lookup time.

Signed-off-by: Changman Lee 
Signed-off-by: Jaegeuk Kim

f2fs: fix typo

2014-08-19T17:01:33+00:00

Fix typo and some grammatical errors.

The words "filesystem" and "readahead" are being used without the space treewide.

Signed-off-by: Park Ju Hyung 
Signed-off-by: Jaegeuk Kim

f2fs: add a sysfs entry to control max_victim_search

2014-01-08T04:45:08+00:00

Previously during SSR and GC, the maximum number of retrials to find a victim
segment was hard-coded by MAX_VICTIM_SEARCH, 4096 by default.

This number makes an effect on IO locality, when SSR mode is activated, which
results in performance fluctuation on some low-end devices.

If max_victim_search = 4, the victim will be searched like below.
("D" represents a dirty segment, and "*" indicates a selected victim segment.)

 D1 D2 D3 D4 D5 D6 D7 D8 D9
[   *       ]
      [   *    ]
            [         * ]
	                [ ....]

This patch adds a sysfs entry to control the number dynamically through:
  /sys/fs/f2fs/$dev/max_victim_search

Signed-off-by: Jaegeuk Kim

f2fs: optimize gc for better performance

2013-09-05T04:50:32+00:00

This patch improves the gc efficiency by optimizing the victim
selection policy. With this optimization, the random re-write
performance could increase up to 20%.

For f2fs, when disk is in shortage of free spaces, gc will selects
dirty segments and moves valid blocks around for making more space
available. The gc cost of a segment is determined by the valid blocks
in the segment. The less the valid blocks, the higher the efficiency.
The ideal victim segment is the one that has the most garbage blocks.

Currently, it searches up to 20 dirty segments for a victim segment.
The selected victim is not likely the best victim for gc when there
are much more dirty segments. Why not searching more dirty segments
for a better victim? The cost of searching dirty segments is
negligible in comparison to moving blocks.

In this patch, it enlarges the MAX_VICTIM_SEARCH to 4096 to make
the search more aggressively for a possible better victim. Since
it also applies to victim selection for SSR, it will likely improve
the SSR efficiency as well.

The test case is simple. It creates as many files until the disk full.
The size for each file is 32KB. Then it writes as many as 100000
records of 4KB size to random offsets of random files in sync mode.
The testing was done on a 2GB partition of a SDHC card. Let's see the
test result of f2fs without and with the patch.

---------------------------------------
2GB partition, SDHC
create 52023 files of size 32768 bytes
random re-write 100000 records of 4KB
---------------------------------------
| file creation (s) | rewrite time (s) | gc count | gc garbage blocks |
[no patch]  341         4227             1174          174840
[patched]   324         2958             645           106682

It's obvious that, with the patch, f2fs finishes the test in 20+% less
time than without the patch. And internally it does much less gc with
higher efficiency than before.

Since the performance improvement is related to gc, it might not be so
obvious for other tests that do not trigger gc as often as this one (
This is because f2fs selects dirty segments for SSR use most of the
time when free space is in shortage). The well-known iozone test tool
was not used for benchmarking the patch becuase it seems do not have
a test case that performs random re-write on a full disk.

This patch is the revised version based on the suggestion from
Jaegeuk Kim.

Signed-off-by: Jin Xu 
[Jaegeuk Kim: suggested simpler solution]
Reviewed-by: Jaegeuk Kim 
Signed-off-by: Jaegeuk Kim

f2fs: add sysfs entries to select the gc policy

2013-08-06T13:00:18+00:00

Add sysfs entry gc_idle to control the gc policy. Where
gc_idle = 1 corresponds to selecting a cost benefit approach,
while gc_idle = 2 corresponds to selecting a greedy approach
to garbage collection. The selection is mutually exclusive one
approach will work at any point. If gc_idle = 0, then this
option is disabled.

Cc: Gu Zheng 
Signed-off-by: Namjae Jeon 
Signed-off-by: Pankaj Kumar 
Reviewed-by: Gu Zheng 
[Jaegeuk Kim: change the select_gc_type() flow slightly]
Signed-off-by: Jaegeuk Kim