linux/Documentation/ABI/testing/sysfs-fs-f2fs
Chao Yu 969d1b180d f2fs: introduce discard_granularity sysfs entry
Commit d618ebaf0a ("f2fs: enable small discard by default") enables
f2fs to issue 4K size discard in real-time discard mode. However, issuing
smaller discard may cost more lifetime but releasing less free space in
flash device. Since f2fs has ability of separating hot/cold data and
garbage collection, we can expect that small-sized invalid region would
expand soon with OPU, deletion or garbage collection on valid datas, so
it's better to delay or skip issuing smaller size discards, it could help
to reduce overmuch consumption of IO bandwidth and lifetime of flash
storage.

This patch makes f2fs selectng 64K size as its default minimal
granularity, and issue discard with the size which is not smaller than
minimal granularity. Also it exposes discard granularity as sysfs entry
for configuration in different scenario.

Jaegeuk Kim:
 We must issue all the accumulated discard commands when fstrim is called.
 So, I've added pend_list_tag[] to indicate whether we should issue the
 commands or not. If tag sets P_ACTIVE or P_TRIM, we have to issue them.
 P_TRIM is set once at a time, given fstrim trigger.
 In addition, issue_discard_thread is calling too much due to the number of
 discard commands remaining in the pending list. I added a timer to control
 it likewise gc_thread.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2017-08-21 15:55:07 -07:00

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What: /sys/fs/f2fs/<disk>/gc_max_sleep_time
Date: July 2013
Contact: "Namjae Jeon" <namjae.jeon@samsung.com>
Description:
Controls the maximun sleep time for gc_thread. Time
is in milliseconds.
What: /sys/fs/f2fs/<disk>/gc_min_sleep_time
Date: July 2013
Contact: "Namjae Jeon" <namjae.jeon@samsung.com>
Description:
Controls the minimum sleep time for gc_thread. Time
is in milliseconds.
What: /sys/fs/f2fs/<disk>/gc_no_gc_sleep_time
Date: July 2013
Contact: "Namjae Jeon" <namjae.jeon@samsung.com>
Description:
Controls the default sleep time for gc_thread. Time
is in milliseconds.
What: /sys/fs/f2fs/<disk>/gc_idle
Date: July 2013
Contact: "Namjae Jeon" <namjae.jeon@samsung.com>
Description:
Controls the victim selection policy for garbage collection.
What: /sys/fs/f2fs/<disk>/reclaim_segments
Date: October 2013
Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
Description:
Controls the issue rate of segment discard commands.
What: /sys/fs/f2fs/<disk>/ipu_policy
Date: November 2013
Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
Description:
Controls the in-place-update policy.
What: /sys/fs/f2fs/<disk>/min_ipu_util
Date: November 2013
Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
Description:
Controls the FS utilization condition for the in-place-update
policies.
What: /sys/fs/f2fs/<disk>/min_fsync_blocks
Date: September 2014
Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
Description:
Controls the dirty page count condition for the in-place-update
policies.
What: /sys/fs/f2fs/<disk>/max_small_discards
Date: November 2013
Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
Description:
Controls the issue rate of small discard commands.
What: /sys/fs/f2fs/<disk>/discard_granularity
Date: July 2017
Contact: "Chao Yu" <yuchao0@huawei.com>
Description:
Controls discard granularity of inner discard thread, inner thread
will not issue discards with size that is smaller than granularity.
The unit size is one block, now only support configuring in range
of [1, 512].
What: /sys/fs/f2fs/<disk>/max_victim_search
Date: January 2014
Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
Description:
Controls the number of trials to find a victim segment.
What: /sys/fs/f2fs/<disk>/dir_level
Date: March 2014
Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
Description:
Controls the directory level for large directory.
What: /sys/fs/f2fs/<disk>/ram_thresh
Date: March 2014
Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
Description:
Controls the memory footprint used by f2fs.
What: /sys/fs/f2fs/<disk>/batched_trim_sections
Date: February 2015
Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
Description:
Controls the trimming rate in batch mode.
What: /sys/fs/f2fs/<disk>/cp_interval
Date: October 2015
Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
Description:
Controls the checkpoint timing.
What: /sys/fs/f2fs/<disk>/idle_interval
Date: January 2016
Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
Description:
Controls the idle timing.
What: /sys/fs/f2fs/<disk>/ra_nid_pages
Date: October 2015
Contact: "Chao Yu" <chao2.yu@samsung.com>
Description:
Controls the count of nid pages to be readaheaded.
What: /sys/fs/f2fs/<disk>/dirty_nats_ratio
Date: January 2016
Contact: "Chao Yu" <chao2.yu@samsung.com>
Description:
Controls dirty nat entries ratio threshold, if current
ratio exceeds configured threshold, checkpoint will
be triggered for flushing dirty nat entries.
What: /sys/fs/f2fs/<disk>/lifetime_write_kbytes
Date: January 2016
Contact: "Shuoran Liu" <liushuoran@huawei.com>
Description:
Shows total written kbytes issued to disk.
What: /sys/fs/f2fs/<disk>/inject_rate
Date: May 2016
Contact: "Sheng Yong" <shengyong1@huawei.com>
Description:
Controls the injection rate.
What: /sys/fs/f2fs/<disk>/inject_type
Date: May 2016
Contact: "Sheng Yong" <shengyong1@huawei.com>
Description:
Controls the injection type.
What: /sys/fs/f2fs/<disk>/reserved_blocks
Date: June 2017
Contact: "Chao Yu" <yuchao0@huawei.com>
Description:
Controls current reserved blocks in system.
What: /sys/fs/f2fs/<disk>/gc_urgent
Date: August 2017
Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
Description:
Do background GC agressively
What: /sys/fs/f2fs/<disk>/gc_urgent_sleep_time
Date: August 2017
Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
Description:
Controls sleep time of GC urgent mode