linux.git/fs/f2fs/node.c, branch v4.11

f2fs: combine nat_bits and free_nid_bitmap cache

2017-03-20T14:00:18+00:00

Both nat_bits cache and free_nid_bitmap cache provide same functionality
as a intermediate cache between free nid cache and disk, but with
different granularity of indicating free nid range, and different
persistence policy. nat_bits cache provides better persistence ability,
and free_nid_bitmap provides better granularity.

In this patch we combine advantage of both caches, so finally policy of
the intermediate cache would be:
- init: load free nid status from nat_bits into free_nid_bitmap
- lookup: scan free_nid_bitmap before load NAT blocks
- update: update free_nid_bitmap in real-time
- persistence: udpate and persist nat_bits in checkpoint

This patch also resolves performance regression reported by lkp-robot.

commit:
  4ac912427c4214d8031d9ad6fbc3bc75e71512df ("f2fs: introduce free nid bitmap")
  d00030cf9cd0bb96fdccc41e33d3c91dcbb672ba ("f2fs: use __set{__clear}_bit_le")
  1382c0f3f9d3f936c8bc42ed1591cf7a593ef9f7 ("f2fs: combine nat_bits and free_nid_bitmap cache")

4ac912427c4214d8 d00030cf9cd0bb96fdccc41e33 1382c0f3f9d3f936c8bc42ed15
---------------- -------------------------- --------------------------
         %stddev     %change         %stddev     %change         %stddev
             \          |                \          |                \
     77863 ±  0%      +2.1%      79485 ±  1%     +50.8%     117404 ±  0%  aim7.jobs-per-min
    231.63 ±  0%      -2.0%     227.01 ±  1%     -33.6%     153.80 ±  0%  aim7.time.elapsed_time
    231.63 ±  0%      -2.0%     227.01 ±  1%     -33.6%     153.80 ±  0%  aim7.time.elapsed_time.max
    896604 ±  0%      -0.8%     889221 ±  3%     -20.2%     715260 ±  1%  aim7.time.involuntary_context_switches
      2394 ±  1%      +4.6%       2503 ±  1%      +3.7%       2481 ±  2%  aim7.time.maximum_resident_set_size
      6240 ±  0%      -1.5%       6145 ±  1%     -14.1%       5360 ±  1%  aim7.time.system_time
   1111357 ±  3%      +1.9%    1132509 ±  2%      -6.2%    1041932 ±  2%  aim7.time.voluntary_context_switches
...

Signed-off-by: Chao Yu 
Tested-by: Xiaolong Ye 
Signed-off-by: Jaegeuk Kim

f2fs: skip scanning free nid bitmap of full NAT blocks

2017-03-20T14:00:17+00:00

This patch adds to account free nids for each NAT blocks, and while
scanning all free nid bitmap, do check count and skip lookuping in
full NAT block.

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

f2fs: use set{clear}_bit_le

2017-03-20T14:00:16+00:00

This patch uses __set{__clear}_bit_le for highter speed.

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

f2fs: declare static functions

2017-03-20T14:00:15+00:00

This is to avoid build warning reported by kbuild test robot.

Signed-off-by: Fengguang Wu 
Signed-off-by: Jaegeuk Kim

f2fs: avoid to flush nat journal entries

2017-02-28T17:57:13+00:00

This patch adds a missing condition which flushes nat journal entries
unnecessarily introduced by:

    f2fs: add bitmaps for empty or full NAT blocks

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

f2fs: use MAX_FREE_NIDS for the free nids target

2017-02-27T18:07:48+00:00

F2FS has define MAX_FREE_NIDS for maximum of cached free nids target.

Signed-off-by: Kinglong Mee 
Reviewed-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: introduce free nid bitmap

2017-02-27T18:07:47+00:00

In scenario of intensively node allocation, free nids will be ran out
soon, then it needs to stop to load free nids by traversing NAT blocks,
in worse case, if NAT blocks does not be cached in memory, it generates
IOs which slows down our foreground operations.

In order to speed up node allocation, in this patch we introduce a new
free_nid_bitmap array, so there is an bitmap table for each NAT block,
Once the NAT block is loaded, related bitmap cache will be switched on,
and bitmap will be set during traversing nat entries in NAT block, later
we can query and update nid usage status in memory completely.

With such implementation, I expect performance of node allocation can be
improved in the long-term after filesystem image is mounted.

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

f2fs: new helper cur_cp_crc() getting crc in f2fs_checkpoint

2017-02-27T18:07:47+00:00

There are four places that getting the crc value in f2fs_checkpoint,
just add a new helper cur_cp_crc for them.

Signed-off-by: Kinglong Mee 
Signed-off-by: Jaegeuk Kim

f2fs: show simple call stack in fault injection message

2017-02-27T17:59:55+00:00

Previously kernel message can show that in which function we do the
injection, but unfortunately, most of the caller are the same, for
tracking more information of injection path, it needs to show upper
caller's name. This patch supports that ability.

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

f2fs: add bitmaps for empty or full NAT blocks

2017-02-27T17:59:54+00:00

This patches adds bitmaps to represent empty or full NAT blocks containing
free nid entries.

If we can find valid crc|cp_ver in the last block of checkpoint pack, we'll
use these bitmaps when building free nids. In order to avoid checkpointing
burden, up-to-date bitmaps will be flushed only during umount time. So,
normally we can get this gain, but when power-cut happens, we rely on fsck.f2fs
which recovers this bitmap again.

After this patch, we build free nids from nid #0 at mount time to make more
full NAT blocks, but in runtime, we check empty NAT blocks to load free nids
without loading any NAT pages from disk.

Signed-off-by: Jaegeuk Kim