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:    Shows first block address of MAIN area.
  45
  46 What:           /sys/fs/f2fs/<disk>/ipu_policy
  47 Date:           November 2013
  48 Contact:        "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
  49 Description:    Controls the in-place-update policy.
  50                 updates in f2fs. User can set:
  51
  52                 ====  =================
  53                 0x01  F2FS_IPU_FORCE
  54                 0x02  F2FS_IPU_SSR
  55                 0x04  F2FS_IPU_UTIL
  56                 0x08  F2FS_IPU_SSR_UTIL
  57                 0x10  F2FS_IPU_FSYNC
  58                 0x20  F2FS_IPU_ASYNC,
  59                 0x40  F2FS_IPU_NOCACHE
  60                 ====  =================
  61
  62                 Refer segment.h for details.
  63
  64 What:           /sys/fs/f2fs/<disk>/min_ipu_util
  65 Date:           November 2013
  66 Contact:        "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
  67 Description:    Controls the FS utilization condition for the in-place-update
  68                 policies. It is used by F2FS_IPU_UTIL and F2FS_IPU_SSR_UTIL policies.
  69
  70 What:           /sys/fs/f2fs/<disk>/min_fsync_blocks
  71 Date:           September 2014
  72 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
  73 Description:    Controls the dirty page count condition for the in-place-update
  74                 policies.
  75
  76 What:           /sys/fs/f2fs/<disk>/min_seq_blocks
  77 Date:           August 2018
  78 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
  79 Description:    Controls the dirty page count condition for batched sequential
  80                 writes in writepages.
  81
  82 What:           /sys/fs/f2fs/<disk>/min_hot_blocks
  83 Date:           March 2017
  84 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
  85 Description:    Controls the dirty page count condition for redefining hot data.
  86
  87 What:           /sys/fs/f2fs/<disk>/min_ssr_sections
  88 Date:           October 2017
  89 Contact:        "Chao Yu" <yuchao0@huawei.com>
  90 Description:    Controls the free section threshold to trigger SSR allocation.
  91                 If this is large, SSR mode will be enabled early.
  92
  93 What:           /sys/fs/f2fs/<disk>/max_small_discards
  94 Date:           November 2013
  95 Contact:        "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
  96 Description:    Controls the issue rate of discard commands that consist of small
  97                 blocks less than 2MB. The candidates to be discarded are cached until
  98                 checkpoint is triggered, and issued during the checkpoint.
  99                 By default, it is disabled with 0.
 100
 101 What:           /sys/fs/f2fs/<disk>/discard_granularity
 102 Date:           July 2017
 103 Contact:        "Chao Yu" <yuchao0@huawei.com>
 104 Description:    Controls discard granularity of inner discard thread. Inner thread
 105                 will not issue discards with size that is smaller than granularity.
 106                 The unit size is one block(4KB), now only support configuring
 107                 in range of [1, 512]. Default value is 4(=16KB).
 108
 109 What:           /sys/fs/f2fs/<disk>/umount_discard_timeout
 110 Date:           January 2019
 111 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 112 Description:    Set timeout to issue discard commands during umount.
 113                 Default: 5 secs
 114
 115 What:           /sys/fs/f2fs/<disk>/max_victim_search
 116 Date:           January 2014
 117 Contact:        "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
 118 Description:    Controls the number of trials to find a victim segment
 119                 when conducting SSR and cleaning operations. The default value
 120                 is 4096 which covers 8GB block address range.
 121
 122 What:           /sys/fs/f2fs/<disk>/migration_granularity
 123 Date:           October 2018
 124 Contact:        "Chao Yu" <yuchao0@huawei.com>
 125 Description:    Controls migration granularity of garbage collection on large
 126                 section, it can let GC move partial segment{s} of one section
 127                 in one GC cycle, so that dispersing heavy overhead GC to
 128                 multiple lightweight one.
 129
 130 What:           /sys/fs/f2fs/<disk>/dir_level
 131 Date:           March 2014
 132 Contact:        "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
 133 Description:    Controls the directory level for large directory. If a
 134                 directory has a number of files, it can reduce the file lookup
 135                 latency by increasing this dir_level value. Otherwise, it
 136                 needs to decrease this value to reduce the space overhead.
 137                 The default value is 0.
 138
 139 What:           /sys/fs/f2fs/<disk>/ram_thresh
 140 Date:           March 2014
 141 Contact:        "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
 142 Description:    Controls the memory footprint used by free nids and cached
 143                 nat entries. By default, 1 is set, which indicates
 144                 10 MB / 1 GB RAM.
 145
 146 What:           /sys/fs/f2fs/<disk>/batched_trim_sections
 147 Date:           February 2015
 148 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 149 Description:    Controls the trimming rate in batch mode.
 150                 <deprecated>
 151
 152 What:           /sys/fs/f2fs/<disk>/cp_interval
 153 Date:           October 2015
 154 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 155 Description:    Controls the checkpoint timing, set to 60 seconds by default.
 156
 157 What:           /sys/fs/f2fs/<disk>/idle_interval
 158 Date:           January 2016
 159 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 160 Description:    Controls the idle timing of system, if there is no FS operation
 161                 during given interval.
 162                 Set to 5 seconds by default.
 163
 164 What:           /sys/fs/f2fs/<disk>/discard_idle_interval
 165 Date:           September 2018
 166 Contact:        "Chao Yu" <yuchao0@huawei.com>
 167 Contact:        "Sahitya Tummala" <stummala@codeaurora.org>
 168 Description:    Controls the idle timing of discard thread given
 169                 this time interval.
 170                 Default is 5 secs.
 171
 172 What:           /sys/fs/f2fs/<disk>/gc_idle_interval
 173 Date:           September 2018
 174 Contact:        "Chao Yu" <yuchao0@huawei.com>
 175 Contact:        "Sahitya Tummala" <stummala@codeaurora.org>
 176 Description:    Controls the idle timing for gc path. Set to 5 seconds by default.
 177
 178 What:           /sys/fs/f2fs/<disk>/iostat_enable
 179 Date:           August 2017
 180 Contact:        "Chao Yu" <yuchao0@huawei.com>
 181 Description:    Controls to enable/disable IO stat.
 182
 183 What:           /sys/fs/f2fs/<disk>/ra_nid_pages
 184 Date:           October 2015
 185 Contact:        "Chao Yu" <chao2.yu@samsung.com>
 186 Description:    Controls the count of nid pages to be readaheaded.
 187                 When building free nids, F2FS reads NAT blocks ahead for
 188                 speed up. Default is 0.
 189
 190 What:           /sys/fs/f2fs/<disk>/dirty_nats_ratio
 191 Date:           January 2016
 192 Contact:        "Chao Yu" <chao2.yu@samsung.com>
 193 Description:    Controls dirty nat entries ratio threshold, if current
 194                 ratio exceeds configured threshold, checkpoint will
 195                 be triggered for flushing dirty nat entries.
 196
 197 What:           /sys/fs/f2fs/<disk>/lifetime_write_kbytes
 198 Date:           January 2016
 199 Contact:        "Shuoran Liu" <liushuoran@huawei.com>
 200 Description:    Shows total written kbytes issued to disk.
 201
 202 What:           /sys/fs/f2fs/<disk>/features
 203 Date:           July 2017
 204 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 205 Description:    <deprecated: should use /sys/fs/f2fs/<disk>/feature_list/
 206                 Shows all enabled features in current device.
 207                 Supported features:
 208                 encryption, blkzoned, extra_attr, projquota, inode_checksum,
 209                 flexible_inline_xattr, quota_ino, inode_crtime, lost_found,
 210                 verity, sb_checksum, casefold, readonly, compression, pin_file.
 211
 212 What:           /sys/fs/f2fs/<disk>/feature_list/
 213 Date:           June 2021
 214 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 215 Description:    Expand /sys/fs/f2fs/<disk>/features to meet sysfs rule.
 216                 Supported on-disk features:
 217                 encryption, block_zoned (aka blkzoned), extra_attr,
 218                 project_quota (aka projquota), inode_checksum,
 219                 flexible_inline_xattr, quota_ino, inode_crtime, lost_found,
 220                 verity, sb_checksum, casefold, readonly, compression.
 221                 Note that, pin_file is moved into /sys/fs/f2fs/features/.
 222
 223 What:           /sys/fs/f2fs/features/
 224 Date:           July 2017
 225 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 226 Description:    Shows all enabled kernel features.
 227                 Supported features:
 228                 encryption, block_zoned, extra_attr, project_quota,
 229                 inode_checksum, flexible_inline_xattr, quota_ino,
 230                 inode_crtime, lost_found, verity, sb_checksum,
 231                 casefold, readonly, compression, test_dummy_encryption_v2,
 232                 atomic_write, pin_file, encrypted_casefold.
 233
 234 What:           /sys/fs/f2fs/<disk>/inject_rate
 235 Date:           May 2016
 236 Contact:        "Sheng Yong" <shengyong1@huawei.com>
 237 Description:    Controls the injection rate of arbitrary faults.
 238
 239 What:           /sys/fs/f2fs/<disk>/inject_type
 240 Date:           May 2016
 241 Contact:        "Sheng Yong" <shengyong1@huawei.com>
 242 Description:    Controls the injection type of arbitrary faults.
 243
 244 What:           /sys/fs/f2fs/<disk>/dirty_segments
 245 Date:           October 2017
 246 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 247 Description:    Shows the number of dirty segments.
 248
 249 What:           /sys/fs/f2fs/<disk>/reserved_blocks
 250 Date:           June 2017
 251 Contact:        "Chao Yu" <yuchao0@huawei.com>
 252 Description:    Controls target reserved blocks in system, the threshold
 253                 is soft, it could exceed current available user space.
 254
 255 What:           /sys/fs/f2fs/<disk>/current_reserved_blocks
 256 Date:           October 2017
 257 Contact:        "Yunlong Song" <yunlong.song@huawei.com>
 258 Contact:        "Chao Yu" <yuchao0@huawei.com>
 259 Description:    Shows current reserved blocks in system, it may be temporarily
 260                 smaller than target_reserved_blocks, but will gradually
 261                 increase to target_reserved_blocks when more free blocks are
 262                 freed by user later.
 263
 264 What:           /sys/fs/f2fs/<disk>/gc_urgent
 265 Date:           August 2017
 266 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 267 Description:    Do background GC aggressively when set. When gc_urgent = 1,
 268                 background thread starts to do GC by given gc_urgent_sleep_time
 269                 interval. When gc_urgent = 2, F2FS will lower the bar of
 270                 checking idle in order to process outstanding discard commands
 271                 and GC a little bit aggressively. It is set to 0 by default.
 272
 273 What:           /sys/fs/f2fs/<disk>/gc_urgent_sleep_time
 274 Date:           August 2017
 275 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 276 Description:    Controls sleep time of GC urgent mode. Set to 500ms by default.
 277
 278 What:           /sys/fs/f2fs/<disk>/readdir_ra
 279 Date:           November 2017
 280 Contact:        "Sheng Yong" <shengyong1@huawei.com>
 281 Description:    Controls readahead inode block in readdir. Enabled by default.
 282
 283 What:           /sys/fs/f2fs/<disk>/gc_pin_file_thresh
 284 Date:           January 2018
 285 Contact:        Jaegeuk Kim <jaegeuk@kernel.org>
 286 Description:    This indicates how many GC can be failed for the pinned
 287                 file. If it exceeds this, F2FS doesn't guarantee its pinning
 288                 state. 2048 trials is set by default.
 289
 290 What:           /sys/fs/f2fs/<disk>/extension_list
 291 Date:           Feburary 2018
 292 Contact:        "Chao Yu" <yuchao0@huawei.com>
 293 Description:    Used to control configure extension list:
 294                 - Query: cat /sys/fs/f2fs/<disk>/extension_list
 295                 - Add: echo '[h/c]extension' > /sys/fs/f2fs/<disk>/extension_list
 296                 - Del: echo '[h/c]!extension' > /sys/fs/f2fs/<disk>/extension_list
 297                 - [h] means add/del hot file extension
 298                 - [c] means add/del cold file extension
 299
 300 What:           /sys/fs/f2fs/<disk>/unusable
 301 Date            April 2019
 302 Contact:        "Daniel Rosenberg" <drosen@google.com>
 303 Description:    If checkpoint=disable, it displays the number of blocks that
 304                 are unusable.
 305                 If checkpoint=enable it displays the number of blocks that
 306                 would be unusable if checkpoint=disable were to be set.
 307
 308 What:           /sys/fs/f2fs/<disk>/encoding
 309 Date            July 2019
 310 Contact:        "Daniel Rosenberg" <drosen@google.com>
 311 Description:    Displays name and version of the encoding set for the filesystem.
 312                 If no encoding is set, displays (none)
 313
 314 What:           /sys/fs/f2fs/<disk>/free_segments
 315 Date:           September 2019
 316 Contact:        "Hridya Valsaraju" <hridya@google.com>
 317 Description:    Number of free segments in disk.
 318
 319 What:           /sys/fs/f2fs/<disk>/cp_foreground_calls
 320 Date:           September 2019
 321 Contact:        "Hridya Valsaraju" <hridya@google.com>
 322 Description:    Number of checkpoint operations performed on demand. Available when
 323                 CONFIG_F2FS_STAT_FS=y.
 324
 325 What:           /sys/fs/f2fs/<disk>/cp_background_calls
 326 Date:           September 2019
 327 Contact:        "Hridya Valsaraju" <hridya@google.com>
 328 Description:    Number of checkpoint operations performed in the background to
 329                 free segments. Available when CONFIG_F2FS_STAT_FS=y.
 330
 331 What:           /sys/fs/f2fs/<disk>/gc_foreground_calls
 332 Date:           September 2019
 333 Contact:        "Hridya Valsaraju" <hridya@google.com>
 334 Description:    Number of garbage collection operations performed on demand.
 335                 Available when CONFIG_F2FS_STAT_FS=y.
 336
 337 What:           /sys/fs/f2fs/<disk>/gc_background_calls
 338 Date:           September 2019
 339 Contact:        "Hridya Valsaraju" <hridya@google.com>
 340 Description:    Number of garbage collection operations triggered in background.
 341                 Available when CONFIG_F2FS_STAT_FS=y.
 342
 343 What:           /sys/fs/f2fs/<disk>/moved_blocks_foreground
 344 Date:           September 2019
 345 Contact:        "Hridya Valsaraju" <hridya@google.com>
 346 Description:    Number of blocks moved by garbage collection in foreground.
 347                 Available when CONFIG_F2FS_STAT_FS=y.
 348
 349 What:           /sys/fs/f2fs/<disk>/moved_blocks_background
 350 Date:           September 2019
 351 Contact:        "Hridya Valsaraju" <hridya@google.com>
 352 Description:    Number of blocks moved by garbage collection in background.
 353                 Available when CONFIG_F2FS_STAT_FS=y.
 354
 355 What:           /sys/fs/f2fs/<disk>/avg_vblocks
 356 Date:           September 2019
 357 Contact:        "Hridya Valsaraju" <hridya@google.com>
 358 Description:    Average number of valid blocks.
 359                 Available when CONFIG_F2FS_STAT_FS=y.
 360
 361 What:           /sys/fs/f2fs/<disk>/mounted_time_sec
 362 Date:           February 2020
 363 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 364 Description:    Show the mounted time in secs of this partition.
 365
 366 What:           /sys/fs/f2fs/<disk>/data_io_flag
 367 Date:           April 2020
 368 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 369 Description:    Give a way to attach REQ_META|FUA to data writes
 370                 given temperature-based bits. Now the bits indicate:
 371
 372                 +-------------------+-------------------+
 373                 |      REQ_META     |      REQ_FUA      |
 374                 +------+------+-----+------+------+-----+
 375                 |    5 |    4 |   3 |    2 |    1 |   0 |
 376                 +------+------+-----+------+------+-----+
 377                 | Cold | Warm | Hot | Cold | Warm | Hot |
 378                 +------+------+-----+------+------+-----+
 379
 380 What:           /sys/fs/f2fs/<disk>/node_io_flag
 381 Date:           June 2020
 382 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 383 Description:    Give a way to attach REQ_META|FUA to node writes
 384                 given temperature-based bits. Now the bits indicate:
 385
 386                 +-------------------+-------------------+
 387                 |      REQ_META     |      REQ_FUA      |
 388                 +------+------+-----+------+------+-----+
 389                 |    5 |    4 |   3 |    2 |    1 |   0 |
 390                 +------+------+-----+------+------+-----+
 391                 | Cold | Warm | Hot | Cold | Warm | Hot |
 392                 +------+------+-----+------+------+-----+
 393
 394 What:           /sys/fs/f2fs/<disk>/iostat_period_ms
 395 Date:           April 2020
 396 Contact:        "Daeho Jeong" <daehojeong@google.com>
 397 Description:    Give a way to change iostat_period time. 3secs by default.
 398                 The new iostat trace gives stats gap given the period.
 399 What:           /sys/fs/f2fs/<disk>/max_io_bytes
 400 Date:           December 2020
 401 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 402 Description:    This gives a control to limit the bio size in f2fs.
 403                 Default is zero, which will follow underlying block layer limit,
 404                 whereas, if it has a certain bytes value, f2fs won't submit a
 405                 bio larger than that size.
 406
 407 What:           /sys/fs/f2fs/<disk>/stat/sb_status
 408 Date:           December 2020
 409 Contact:        "Chao Yu" <yuchao0@huawei.com>
 410 Description:    Show status of f2fs superblock in real time.
 411
 412                 ====== ===================== =================================
 413                 value  sb status macro       description
 414                 0x1    SBI_IS_DIRTY          dirty flag for checkpoint
 415                 0x2    SBI_IS_CLOSE          specify unmounting
 416                 0x4    SBI_NEED_FSCK         need fsck.f2fs to fix
 417                 0x8    SBI_POR_DOING         recovery is doing or not
 418                 0x10   SBI_NEED_SB_WRITE     need to recover superblock
 419                 0x20   SBI_NEED_CP           need to checkpoint
 420                 0x40   SBI_IS_SHUTDOWN       shutdown by ioctl
 421                 0x80   SBI_IS_RECOVERED      recovered orphan/data
 422                 0x100  SBI_CP_DISABLED       CP was disabled last mount
 423                 0x200  SBI_CP_DISABLED_QUICK CP was disabled quickly
 424                 0x400  SBI_QUOTA_NEED_FLUSH  need to flush quota info in CP
 425                 0x800  SBI_QUOTA_SKIP_FLUSH  skip flushing quota in current CP
 426                 0x1000 SBI_QUOTA_NEED_REPAIR quota file may be corrupted
 427                 0x2000 SBI_IS_RESIZEFS       resizefs is in process
 428                 ====== ===================== =================================
 429
 430 What:           /sys/fs/f2fs/<disk>/ckpt_thread_ioprio
 431 Date:           January 2021
 432 Contact:        "Daeho Jeong" <daehojeong@google.com>
 433 Description:    Give a way to change checkpoint merge daemon's io priority.
 434                 Its default value is "be,3", which means "BE" I/O class and
 435                 I/O priority "3". We can select the class between "rt" and "be",
 436                 and set the I/O priority within valid range of it. "," delimiter
 437                 is necessary in between I/O class and priority number.
 438
 439 What:           /sys/fs/f2fs/<disk>/ovp_segments
 440 Date:           March 2021
 441 Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
 442 Description:    Shows the number of overprovision segments.
 443
 444 What:           /sys/fs/f2fs/<disk>/compr_written_block
 445 Date:           March 2021
 446 Contact:        "Daeho Jeong" <daehojeong@google.com>
 447 Description:    Show the block count written after compression since mount. Note
 448                 that when the compressed blocks are deleted, this count doesn't
 449                 decrease. If you write "0" here, you can initialize
 450                 compr_written_block and compr_saved_block to "0".
 451
 452 What:           /sys/fs/f2fs/<disk>/compr_saved_block
 453 Date:           March 2021
 454 Contact:        "Daeho Jeong" <daehojeong@google.com>
 455 Description:    Show the saved block count with compression since mount. Note
 456                 that when the compressed blocks are deleted, this count doesn't
 457                 decrease. If you write "0" here, you can initialize
 458                 compr_written_block and compr_saved_block to "0".
 459
 460 What:           /sys/fs/f2fs/<disk>/compr_new_inode
 461 Date:           March 2021
 462 Contact:        "Daeho Jeong" <daehojeong@google.com>
 463 Description:    Show the count of inode newly enabled for compression since mount.
 464                 Note that when the compression is disabled for the files, this count
 465                 doesn't decrease. If you write "0" here, you can initialize
 466                 compr_new_inode to "0".
 467
 468 What:           /sys/fs/f2fs/<disk>/atgc_candidate_ratio
 469 Date:           May 2021
 470 Contact:        "Chao Yu" <yuchao0@huawei.com>
 471 Description:    When ATGC is on, it controls candidate ratio in order to limit total
 472                 number of potential victim in all candidates, the value should be in
 473                 range of [0, 100], by default it was initialized as 20(%).
 474
 475 What:           /sys/fs/f2fs/<disk>/atgc_candidate_count
 476 Date:           May 2021
 477 Contact:        "Chao Yu" <yuchao0@huawei.com>
 478 Description:    When ATGC is on, it controls candidate count in order to limit total
 479                 number of potential victim in all candidates, by default it was
 480                 initialized as 10 (sections).
 481
 482 What:           /sys/fs/f2fs/<disk>/atgc_age_weight
 483 Date:           May 2021
 484 Contact:        "Chao Yu" <yuchao0@huawei.com>
 485 Description:    When ATGC is on, it controls age weight to balance weight proportion
 486                 in between aging and valid blocks, the value should be in range of
 487                 [0, 100], by default it was initialized as 60(%).
 488
 489 What:           /sys/fs/f2fs/<disk>/atgc_age_threshold
 490 Date:           May 2021
 491 Contact:        "Chao Yu" <yuchao0@huawei.com>
 492 Description:    When ATGC is on, it controls age threshold to bypass GCing young
 493                 candidates whose age is not beyond the threshold, by default it was
 494                 initialized as 604800 seconds (equals to 7 days).
 495
 496 What:           /sys/fs/f2fs/<disk>/gc_reclaimed_segments
 497 Date:           July 2021
 498 Contact:        "Daeho Jeong" <daehojeong@google.com>
 499 Description:    Show how many segments have been reclaimed by GC during a specific
 500                 GC mode (0: GC normal, 1: GC idle CB, 2: GC idle greedy,
 501                 3: GC idle AT, 4: GC urgent high, 5: GC urgent low)
 502                 You can re-initialize this value to "0".
 503
 504 What:           /sys/fs/f2fs/<disk>/gc_segment_mode
 505 Date:           July 2021
 506 Contact:        "Daeho Jeong" <daehojeong@google.com>
 507 Description:    You can control for which gc mode the "gc_reclaimed_segments" node shows.
 508                 Refer to the description of the modes in "gc_reclaimed_segments".
 509
 510 What:           /sys/fs/f2fs/<disk>/seq_file_ra_mul
 511 Date:           July 2021
 512 Contact:        "Daeho Jeong" <daehojeong@google.com>
 513 Description:    You can control the multiplier value of bdi device readahead window size
 514                 between 2 (default) and 256 for POSIX_FADV_SEQUENTIAL advise option.