Documentation/ABI/testing/sysfs-fs-f2fs

   1 What:           /sys/fs/f2fs/<disk>/gc_max_sleep_time
   2 Date:           July 2013
   3 Contact:        "Namjae Jeon" <namjae.jeon@samsung.com>
   4 Description:    Controls the maximum sleep time for gc_thread. Time
   5                 is in milliseconds.
   6
   7 What:           /sys/fs/f2fs/<disk>/gc_min_sleep_time
   8 Date:           July 2013
   9 Contact:        "Namjae Jeon" <namjae.jeon@samsung.com>
  10 Description:    Controls the minimum sleep time for gc_thread. Time
  11                 is in milliseconds.
  12
  13 What:           /sys/fs/f2fs/<disk>/gc_no_gc_sleep_time
  14 Date:           July 2013
  15 Contact:        "Namjae Jeon" <namjae.jeon@samsung.com>
  16 Description:    Controls the default sleep time for gc_thread. Time
  17                 is in milliseconds.
  18
  19 What:           /sys/fs/f2fs/<disk>/gc_idle
  20 Date:           July 2013
  21 Contact:        "Namjae Jeon" <namjae.jeon@samsung.com>
  22 Description:    Controls the victim selection policy for garbage collection.
  23                 Setting gc_idle = 0(default) will disable this option. Setting:
  24
  25                 ===========  ===============================================
  26                 gc_idle = 1  will select the Cost Benefit approach & setting
  27                 gc_idle = 2  will select the greedy approach & setting
  28                 gc_idle = 3  will select the age-threshold based approach.
  29                 ===========  ===============================================
  30
  31 What:           /sys/fs/f2fs/<disk>/reclaim_segments
  32 Date:           October 2013
  33 Contact:        "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
  34 Description:    This parameter controls the number of prefree segments to be
  35                 reclaimed. If the number of prefree segments is larger than
  36                 the number of segments in the proportion to the percentage
  37                 over total volume size, f2fs tries to conduct checkpoint to
  38                 reclaim the prefree segments to free segments.
  39                 By default, 5% over total # of segments.
  40
  41 What:           /sys/fs/f2fs/<disk>/main_blkaddr
  42 Date:           November 2019
  43 Contact:        "Ramon Pantin" <pantin@google.com>
  44 Description:
  45                  Shows first block address of MAIN area.
  46
  47 What:           /sys/fs/f2fs/<disk>/ipu_policy
  48 Date:           November 2013
  49 Contact:        "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
  50 Description:    Controls the in-place-update policy.
  51                 updates in f2fs. User can set:
  52
  53                 ====  =================
  54                 0x01  F2FS_IPU_FORCE
  55                 0x02  F2FS_IPU_SSR
  56                 0x04  F2FS_IPU_UTIL
  57                 0x08  F2FS_IPU_SSR_UTIL
  58                 0x10  F2FS_IPU_FSYNC
  59                 0x20  F2FS_IPU_ASYNC,
  60                 0x40  F2FS_IPU_NOCACHE
  61                 ====  =================
  62
  63                 Refer segment.h for details.
  64
  65 What:           /sys/fs/f2fs/<disk>/min_ipu_util
  66 Date:           November 2013
  67 Contact:        "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
  68 Description:    Controls the FS utilization condition for the in-place-update
  69                 policies. It is used by F2FS_IPU_UTIL and F2FS_IPU_SSR_UTIL policies.
  70
  71 What:           /sys/fs/f2fs/<disk>/min_fsync_blocks
  72 Date:           September 2014
  73 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
  74 Description:    Controls the dirty page count condition for the in-place-update
  75                 policies.
  76
  77 What:           /sys/fs/f2fs/<disk>/min_seq_blocks
  78 Date:           August 2018
  79 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
  80 Description:    Controls the dirty page count condition for batched sequential
  81                 writes in writepages.
  82
  83 What:           /sys/fs/f2fs/<disk>/min_hot_blocks
  84 Date:           March 2017
  85 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
  86 Description:    Controls the dirty page count condition for redefining hot data.
  87
  88 What:           /sys/fs/f2fs/<disk>/min_ssr_sections
  89 Date:           October 2017
  90 Contact:        "Chao Yu" <yuchao0@huawei.com>
  91 Description:    Controls the free section threshold to trigger SSR allocation.
  92                 If this is large, SSR mode will be enabled early.
  93
  94 What:           /sys/fs/f2fs/<disk>/max_small_discards
  95 Date:           November 2013
  96 Contact:        "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
  97 Description:    Controls the issue rate of discard commands that consist of small
  98                 blocks less than 2MB. The candidates to be discarded are cached until
  99                 checkpoint is triggered, and issued during the checkpoint.
 100                 By default, it is disabled with 0.
 101
 102 What:           /sys/fs/f2fs/<disk>/discard_granularity
 103 Date:           July 2017
 104 Contact:        "Chao Yu" <yuchao0@huawei.com>
 105 Description:    Controls discard granularity of inner discard thread. Inner thread
 106                 will not issue discards with size that is smaller than granularity.
 107                 The unit size is one block(4KB), now only support configuring
 108                 in range of [1, 512]. Default value is 4(=16KB).
 109
 110 What:           /sys/fs/f2fs/<disk>/umount_discard_timeout
 111 Date:           January 2019
 112 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 113 Description:    Set timeout to issue discard commands during umount.
 114                 Default: 5 secs
 115
 116 What:           /sys/fs/f2fs/<disk>/max_victim_search
 117 Date:           January 2014
 118 Contact:        "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
 119 Description:    Controls the number of trials to find a victim segment
 120                 when conducting SSR and cleaning operations. The default value
 121                 is 4096 which covers 8GB block address range.
 122
 123 What:           /sys/fs/f2fs/<disk>/migration_granularity
 124 Date:           October 2018
 125 Contact:        "Chao Yu" <yuchao0@huawei.com>
 126 Description:    Controls migration granularity of garbage collection on large
 127                 section, it can let GC move partial segment{s} of one section
 128                 in one GC cycle, so that dispersing heavy overhead GC to
 129                 multiple lightweight one.
 130
 131 What:           /sys/fs/f2fs/<disk>/dir_level
 132 Date:           March 2014
 133 Contact:        "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
 134 Description:    Controls the directory level for large directory. If a
 135                 directory has a number of files, it can reduce the file lookup
 136                 latency by increasing this dir_level value. Otherwise, it
 137                 needs to decrease this value to reduce the space overhead.
 138                 The default value is 0.
 139
 140 What:           /sys/fs/f2fs/<disk>/ram_thresh
 141 Date:           March 2014
 142 Contact:        "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
 143 Description:    Controls the memory footprint used by free nids and cached
 144                 nat entries. By default, 1 is set, which indicates
 145                 10 MB / 1 GB RAM.
 146
 147 What:           /sys/fs/f2fs/<disk>/batched_trim_sections
 148 Date:           February 2015
 149 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 150 Description:    Controls the trimming rate in batch mode.
 151                 <deprecated>
 152
 153 What:           /sys/fs/f2fs/<disk>/cp_interval
 154 Date:           October 2015
 155 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 156 Description:    Controls the checkpoint timing, set to 60 seconds by default.
 157
 158 What:           /sys/fs/f2fs/<disk>/idle_interval
 159 Date:           January 2016
 160 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 161 Description:    Controls the idle timing of system, if there is no FS operation
 162                 during given interval.
 163                 Set to 5 seconds by default.
 164
 165 What:           /sys/fs/f2fs/<disk>/discard_idle_interval
 166 Date:           September 2018
 167 Contact:        "Chao Yu" <yuchao0@huawei.com>
 168 Contact:        "Sahitya Tummala" <stummala@codeaurora.org>
 169 Description:    Controls the idle timing of discard thread given
 170                 this time interval.
 171                 Default is 5 secs.
 172
 173 What:           /sys/fs/f2fs/<disk>/gc_idle_interval
 174 Date:           September 2018
 175 Contact:        "Chao Yu" <yuchao0@huawei.com>
 176 Contact:        "Sahitya Tummala" <stummala@codeaurora.org>
 177 Description:    Controls the idle timing for gc path. Set to 5 seconds by default.
 178
 179 What:           /sys/fs/f2fs/<disk>/iostat_enable
 180 Date:           August 2017
 181 Contact:        "Chao Yu" <yuchao0@huawei.com>
 182 Description:    Controls to enable/disable IO stat.
 183
 184 What:           /sys/fs/f2fs/<disk>/ra_nid_pages
 185 Date:           October 2015
 186 Contact:        "Chao Yu" <chao2.yu@samsung.com>
 187 Description:    Controls the count of nid pages to be readaheaded.
 188                 When building free nids, F2FS reads NAT blocks ahead for
 189                 speed up. Default is 0.
 190
 191 What:           /sys/fs/f2fs/<disk>/dirty_nats_ratio
 192 Date:           January 2016
 193 Contact:        "Chao Yu" <chao2.yu@samsung.com>
 194 Description:    Controls dirty nat entries ratio threshold, if current
 195                 ratio exceeds configured threshold, checkpoint will
 196                 be triggered for flushing dirty nat entries.
 197
 198 What:           /sys/fs/f2fs/<disk>/lifetime_write_kbytes
 199 Date:           January 2016
 200 Contact:        "Shuoran Liu" <liushuoran@huawei.com>
 201 Description:    Shows total written kbytes issued to disk.
 202
 203 What:           /sys/fs/f2fs/<disk>/features
 204 Date:           July 2017
 205 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 206 Description:    <deprecated: should use /sys/fs/f2fs/<disk>/feature_list/
 207                 Shows all enabled features in current device.
 208                 Supported features:
 209                 encryption, blkzoned, extra_attr, projquota, inode_checksum,
 210                 flexible_inline_xattr, quota_ino, inode_crtime, lost_found,
 211                 verity, sb_checksum, casefold, readonly, compression, pin_file.
 212
 213 What:           /sys/fs/f2fs/<disk>/feature_list/
 214 Date:           June 2021
 215 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 216 Description:    Expand /sys/fs/f2fs/<disk>/features to meet sysfs rule.
 217                 Supported on-disk features:
 218                 encryption, block_zoned (aka blkzoned), extra_attr,
 219                 project_quota (aka projquota), inode_checksum,
 220                 flexible_inline_xattr, quota_ino, inode_crtime, lost_found,
 221                 verity, sb_checksum, casefold, readonly, compression.
 222                 Note that, pin_file is moved into /sys/fs/f2fs/features/.
 223
 224 What:           /sys/fs/f2fs/features/
 225 Date:           July 2017
 226 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 227 Description:    Shows all enabled kernel features.
 228                 Supported features:
 229                 encryption, block_zoned, extra_attr, project_quota,
 230                 inode_checksum, flexible_inline_xattr, quota_ino,
 231                 inode_crtime, lost_found, verity, sb_checksum,
 232                 casefold, readonly, compression, test_dummy_encryption_v2,
 233                 atomic_write, pin_file, encrypted_casefold.
 234
 235 What:           /sys/fs/f2fs/<disk>/inject_rate
 236 Date:           May 2016
 237 Contact:        "Sheng Yong" <shengyong1@huawei.com>
 238 Description:    Controls the injection rate of arbitrary faults.
 239
 240 What:           /sys/fs/f2fs/<disk>/inject_type
 241 Date:           May 2016
 242 Contact:        "Sheng Yong" <shengyong1@huawei.com>
 243 Description:    Controls the injection type of arbitrary faults.
 244
 245 What:           /sys/fs/f2fs/<disk>/dirty_segments
 246 Date:           October 2017
 247 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 248 Description:    Shows the number of dirty segments.
 249
 250 What:           /sys/fs/f2fs/<disk>/reserved_blocks
 251 Date:           June 2017
 252 Contact:        "Chao Yu" <yuchao0@huawei.com>
 253 Description:    Controls target reserved blocks in system, the threshold
 254                 is soft, it could exceed current available user space.
 255
 256 What:           /sys/fs/f2fs/<disk>/current_reserved_blocks
 257 Date:           October 2017
 258 Contact:        "Yunlong Song" <yunlong.song@huawei.com>
 259 Contact:        "Chao Yu" <yuchao0@huawei.com>
 260 Description:    Shows current reserved blocks in system, it may be temporarily
 261                 smaller than target_reserved_blocks, but will gradually
 262                 increase to target_reserved_blocks when more free blocks are
 263                 freed by user later.
 264
 265 What:           /sys/fs/f2fs/<disk>/gc_urgent
 266 Date:           August 2017
 267 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 268 Description:    Do background GC aggressively when set. When gc_urgent = 1,
 269                 background thread starts to do GC by given gc_urgent_sleep_time
 270                 interval. When gc_urgent = 2, F2FS will lower the bar of
 271                 checking idle in order to process outstanding discard commands
 272                 and GC a little bit aggressively. It is set to 0 by default.
 273
 274 What:           /sys/fs/f2fs/<disk>/gc_urgent_sleep_time
 275 Date:           August 2017
 276 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 277 Description:    Controls sleep time of GC urgent mode. Set to 500ms by default.
 278
 279 What:           /sys/fs/f2fs/<disk>/readdir_ra
 280 Date:           November 2017
 281 Contact:        "Sheng Yong" <shengyong1@huawei.com>
 282 Description:    Controls readahead inode block in readdir. Enabled by default.
 283
 284 What:           /sys/fs/f2fs/<disk>/gc_pin_file_thresh
 285 Date:           January 2018
 286 Contact:        Jaegeuk Kim <jaegeuk@kernel.org>
 287 Description:    This indicates how many GC can be failed for the pinned
 288                 file. If it exceeds this, F2FS doesn't guarantee its pinning
 289                 state. 2048 trials is set by default.
 290
 291 What:           /sys/fs/f2fs/<disk>/extension_list
 292 Date:           Feburary 2018
 293 Contact:        "Chao Yu" <yuchao0@huawei.com>
 294 Description:    Used to control configure extension list:
 295                 - Query: cat /sys/fs/f2fs/<disk>/extension_list
 296                 - Add: echo '[h/c]extension' > /sys/fs/f2fs/<disk>/extension_list
 297                 - Del: echo '[h/c]!extension' > /sys/fs/f2fs/<disk>/extension_list
 298                 - [h] means add/del hot file extension
 299                 - [c] means add/del cold file extension
 300
 301 What:           /sys/fs/f2fs/<disk>/unusable
 302 Date            April 2019
 303 Contact:        "Daniel Rosenberg" <drosen@google.com>
 304 Description:    If checkpoint=disable, it displays the number of blocks that
 305                 are unusable.
 306                 If checkpoint=enable it displays the number of blocks that
 307                 would be unusable if checkpoint=disable were to be set.
 308
 309 What:           /sys/fs/f2fs/<disk>/encoding
 310 Date            July 2019
 311 Contact:        "Daniel Rosenberg" <drosen@google.com>
 312 Description:    Displays name and version of the encoding set for the filesystem.
 313                 If no encoding is set, displays (none)
 314
 315 What:           /sys/fs/f2fs/<disk>/free_segments
 316 Date:           September 2019
 317 Contact:        "Hridya Valsaraju" <hridya@google.com>
 318 Description:    Number of free segments in disk.
 319
 320 What:           /sys/fs/f2fs/<disk>/cp_foreground_calls
 321 Date:           September 2019
 322 Contact:        "Hridya Valsaraju" <hridya@google.com>
 323 Description:    Number of checkpoint operations performed on demand. Available when
 324                 CONFIG_F2FS_STAT_FS=y.
 325
 326 What:           /sys/fs/f2fs/<disk>/cp_background_calls
 327 Date:           September 2019
 328 Contact:        "Hridya Valsaraju" <hridya@google.com>
 329 Description:    Number of checkpoint operations performed in the background to
 330                 free segments. Available when CONFIG_F2FS_STAT_FS=y.
 331
 332 What:           /sys/fs/f2fs/<disk>/gc_foreground_calls
 333 Date:           September 2019
 334 Contact:        "Hridya Valsaraju" <hridya@google.com>
 335 Description:    Number of garbage collection operations performed on demand.
 336                 Available when CONFIG_F2FS_STAT_FS=y.
 337
 338 What:           /sys/fs/f2fs/<disk>/gc_background_calls
 339 Date:           September 2019
 340 Contact:        "Hridya Valsaraju" <hridya@google.com>
 341 Description:    Number of garbage collection operations triggered in background.
 342                 Available when CONFIG_F2FS_STAT_FS=y.
 343
 344 What:           /sys/fs/f2fs/<disk>/moved_blocks_foreground
 345 Date:           September 2019
 346 Contact:        "Hridya Valsaraju" <hridya@google.com>
 347 Description:    Number of blocks moved by garbage collection in foreground.
 348                 Available when CONFIG_F2FS_STAT_FS=y.
 349
 350 What:           /sys/fs/f2fs/<disk>/moved_blocks_background
 351 Date:           September 2019
 352 Contact:        "Hridya Valsaraju" <hridya@google.com>
 353 Description:    Number of blocks moved by garbage collection in background.
 354                 Available when CONFIG_F2FS_STAT_FS=y.
 355
 356 What:           /sys/fs/f2fs/<disk>/avg_vblocks
 357 Date:           September 2019
 358 Contact:        "Hridya Valsaraju" <hridya@google.com>
 359 Description:    Average number of valid blocks.
 360                 Available when CONFIG_F2FS_STAT_FS=y.
 361
 362 What:           /sys/fs/f2fs/<disk>/mounted_time_sec
 363 Date:           February 2020
 364 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 365 Description:    Show the mounted time in secs of this partition.
 366
 367 What:           /sys/fs/f2fs/<disk>/data_io_flag
 368 Date:           April 2020
 369 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 370 Description:    Give a way to attach REQ_META|FUA to data writes
 371                 given temperature-based bits. Now the bits indicate:
 372
 373                 +-------------------+-------------------+
 374                 |      REQ_META     |      REQ_FUA      |
 375                 +------+------+-----+------+------+-----+
 376                 |    5 |    4 |   3 |    2 |    1 |   0 |
 377                 +------+------+-----+------+------+-----+
 378                 | Cold | Warm | Hot | Cold | Warm | Hot |
 379                 +------+------+-----+------+------+-----+
 380
 381 What:           /sys/fs/f2fs/<disk>/node_io_flag
 382 Date:           June 2020
 383 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 384 Description:    Give a way to attach REQ_META|FUA to node writes
 385                 given temperature-based bits. Now the bits indicate:
 386
 387                 +-------------------+-------------------+
 388                 |      REQ_META     |      REQ_FUA      |
 389                 +------+------+-----+------+------+-----+
 390                 |    5 |    4 |   3 |    2 |    1 |   0 |
 391                 +------+------+-----+------+------+-----+
 392                 | Cold | Warm | Hot | Cold | Warm | Hot |
 393                 +------+------+-----+------+------+-----+
 394
 395 What:           /sys/fs/f2fs/<disk>/iostat_period_ms
 396 Date:           April 2020
 397 Contact:        "Daeho Jeong" <daehojeong@google.com>
 398 Description:    Give a way to change iostat_period time. 3secs by default.
 399                 The new iostat trace gives stats gap given the period.
 400 What:           /sys/fs/f2fs/<disk>/max_io_bytes
 401 Date:           December 2020
 402 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 403 Description:    This gives a control to limit the bio size in f2fs.
 404                 Default is zero, which will follow underlying block layer limit,
 405                 whereas, if it has a certain bytes value, f2fs won't submit a
 406                 bio larger than that size.
 407
 408 What:           /sys/fs/f2fs/<disk>/stat/sb_status
 409 Date:           December 2020
 410 Contact:        "Chao Yu" <yuchao0@huawei.com>
 411 Description:    Show status of f2fs superblock in real time.
 412
 413                 ====== ===================== =================================
 414                 value  sb status macro       description
 415                 0x1    SBI_IS_DIRTY          dirty flag for checkpoint
 416                 0x2    SBI_IS_CLOSE          specify unmounting
 417                 0x4    SBI_NEED_FSCK         need fsck.f2fs to fix
 418                 0x8    SBI_POR_DOING         recovery is doing or not
 419                 0x10   SBI_NEED_SB_WRITE     need to recover superblock
 420                 0x20   SBI_NEED_CP           need to checkpoint
 421                 0x40   SBI_IS_SHUTDOWN       shutdown by ioctl
 422                 0x80   SBI_IS_RECOVERED      recovered orphan/data
 423                 0x100  SBI_CP_DISABLED       CP was disabled last mount
 424                 0x200  SBI_CP_DISABLED_QUICK CP was disabled quickly
 425                 0x400  SBI_QUOTA_NEED_FLUSH  need to flush quota info in CP
 426                 0x800  SBI_QUOTA_SKIP_FLUSH  skip flushing quota in current CP
 427                 0x1000 SBI_QUOTA_NEED_REPAIR quota file may be corrupted
 428                 0x2000 SBI_IS_RESIZEFS       resizefs is in process
 429                 ====== ===================== =================================
 430
 431 What:           /sys/fs/f2fs/<disk>/ckpt_thread_ioprio
 432 Date:           January 2021
 433 Contact:        "Daeho Jeong" <daehojeong@google.com>
 434 Description:    Give a way to change checkpoint merge daemon's io priority.
 435                 Its default value is "be,3", which means "BE" I/O class and
 436                 I/O priority "3". We can select the class between "rt" and "be",
 437                 and set the I/O priority within valid range of it. "," delimiter
 438                 is necessary in between I/O class and priority number.
 439
 440 What:           /sys/fs/f2fs/<disk>/ovp_segments
 441 Date:           March 2021
 442 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 443 Description:    Shows the number of overprovision segments.
 444
 445 What:           /sys/fs/f2fs/<disk>/compr_written_block
 446 Date:           March 2021
 447 Contact:        "Daeho Jeong" <daehojeong@google.com>
 448 Description:    Show the block count written after compression since mount. Note
 449                 that when the compressed blocks are deleted, this count doesn't
 450                 decrease. If you write "0" here, you can initialize
 451                 compr_written_block and compr_saved_block to "0".
 452
 453 What:           /sys/fs/f2fs/<disk>/compr_saved_block
 454 Date:           March 2021
 455 Contact:        "Daeho Jeong" <daehojeong@google.com>
 456 Description:    Show the saved block count with compression since mount. Note
 457                 that when the compressed blocks are deleted, this count doesn't
 458                 decrease. If you write "0" here, you can initialize
 459                 compr_written_block and compr_saved_block to "0".
 460
 461 What:           /sys/fs/f2fs/<disk>/compr_new_inode
 462 Date:           March 2021
 463 Contact:        "Daeho Jeong" <daehojeong@google.com>
 464 Description:    Show the count of inode newly enabled for compression since mount.
 465                 Note that when the compression is disabled for the files, this count
 466                 doesn't decrease. If you write "0" here, you can initialize
 467                 compr_new_inode to "0".
 468
 469 What:           /sys/fs/f2fs/<disk>/atgc_candidate_ratio
 470 Date:           May 2021
 471 Contact:        "Chao Yu" <yuchao0@huawei.com>
 472 Description:    When ATGC is on, it controls candidate ratio in order to limit total
 473                 number of potential victim in all candidates, the value should be in
 474                 range of [0, 100], by default it was initialized as 20(%).
 475
 476 What:           /sys/fs/f2fs/<disk>/atgc_candidate_count
 477 Date:           May 2021
 478 Contact:        "Chao Yu" <yuchao0@huawei.com>
 479 Description:    When ATGC is on, it controls candidate count in order to limit total
 480                 number of potential victim in all candidates, by default it was
 481                 initialized as 10 (sections).
 482
 483 What:           /sys/fs/f2fs/<disk>/atgc_age_weight
 484 Date:           May 2021
 485 Contact:        "Chao Yu" <yuchao0@huawei.com>
 486 Description:    When ATGC is on, it controls age weight to balance weight proportion
 487                 in between aging and valid blocks, the value should be in range of
 488                 [0, 100], by default it was initialized as 60(%).
 489
 490 What:           /sys/fs/f2fs/<disk>/atgc_age_threshold
 491 Date:           May 2021
 492 Contact:        "Chao Yu" <yuchao0@huawei.com>
 493 Description:    When ATGC is on, it controls age threshold to bypass GCing young
 494                 candidates whose age is not beyond the threshold, by default it was
 495                 initialized as 604800 seconds (equals to 7 days).