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SubjectRe: [f2fs-dev] [PATCH 5/5 v4] f2fs: introduce a batched trim
Hi Chao,

Something like this?

Change log from v3:
o align to section size

This patch introduces a batched trimming feature, which submits split discard
commands.

This is to avoid long latency due to huge trim commands.
If fstrim was triggered ranging from 0 to the end of device, we should lock
all the checkpoint-related mutexes, resulting in very long latency.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
Documentation/ABI/testing/sysfs-fs-f2fs | 6 ++++++
Documentation/filesystems/f2fs.txt | 4 ++++
fs/f2fs/f2fs.h | 7 +++++++
fs/f2fs/segment.c | 17 ++++++++++++-----
fs/f2fs/super.c | 2 ++
5 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index 6f9157f..2c4cc42 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -74,3 +74,9 @@ Date: March 2014
Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
Description:
Controls the memory footprint used by f2fs.
+
+What: /sys/fs/f2fs/<disk>/trim_sections
+Date: February 2015
+Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
+Description:
+ Controls the trimming rate in batch mode.
diff --git a/Documentation/filesystems/f2fs.txt b/Documentation/filesystems/f2fs.txt
index 6758aa3..dac11d7 100644
--- a/Documentation/filesystems/f2fs.txt
+++ b/Documentation/filesystems/f2fs.txt
@@ -199,6 +199,10 @@ Files in /sys/fs/f2fs/<devname>
checkpoint is triggered, and issued during the
checkpoint. By default, it is disabled with 0.

+ trim_sections This parameter controls the number of sections
+ to be trimmed out in batch mode when FITRIM
+ conducts. 32 sections is set by default.
+
ipu_policy This parameter controls the policy of in-place
updates in f2fs. There are five policies:
0x01: F2FS_IPU_FORCE, 0x02: F2FS_IPU_SSR,
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index db1ff55..d82a10a 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -105,6 +105,10 @@ enum {
CP_DISCARD,
};

+#define DEF_BATCHED_TRIM_SECTIONS 32
+#define BATCHED_TRIM_SEGMENTS(sbi) \
+ (SM_I(sbi)->trim_sections * (sbi)->segs_per_sec)
+
struct cp_control {
int reason;
__u64 trim_start;
@@ -448,6 +452,9 @@ struct f2fs_sm_info {
int nr_discards; /* # of discards in the list */
int max_discards; /* max. discards to be issued */

+ /* for batched trimming */
+ int trim_sections; /* # of sections to trim */
+
struct list_head sit_entry_set; /* sit entry set list */

unsigned int ipu_policy; /* in-place-update policy */
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 5ea57ec..9f278d1 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1066,14 +1066,19 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
end_segno = (end >= MAX_BLKADDR(sbi)) ? MAIN_SEGS(sbi) - 1 :
GET_SEGNO(sbi, end);
cpc.reason = CP_DISCARD;
- cpc.trim_start = start_segno;
- cpc.trim_end = end_segno;
cpc.trim_minlen = range->minlen >> sbi->log_blocksize;

/* do checkpoint to issue discard commands safely */
- mutex_lock(&sbi->gc_mutex);
- write_checkpoint(sbi, &cpc);
- mutex_unlock(&sbi->gc_mutex);
+ for (; start_segno <= end_segno; start_segno = cpc.trim_end + 1) {
+ cpc.trim_start = start_segno;
+ cpc.trim_end = min_t(unsigned int, rounddown(start_segno +
+ BATCHED_TRIM_SEGMENTS(sbi),
+ sbi->segs_per_sec) - 1, end_segno);
+
+ mutex_lock(&sbi->gc_mutex);
+ write_checkpoint(sbi, &cpc);
+ mutex_unlock(&sbi->gc_mutex);
+ }
out:
range->len = cpc.trimmed << sbi->log_blocksize;
return 0;
@@ -2127,6 +2132,8 @@ int build_segment_manager(struct f2fs_sb_info *sbi)
sm_info->nr_discards = 0;
sm_info->max_discards = 0;

+ sm_info->trim_sections = DEF_BATCHED_TRIM_SECTIONS;
+
INIT_LIST_HEAD(&sm_info->sit_entry_set);

if (test_opt(sbi, FLUSH_MERGE) && !f2fs_readonly(sbi->sb)) {
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 1e92c2e..f2fe666 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -195,6 +195,7 @@ F2FS_RW_ATTR(GC_THREAD, f2fs_gc_kthread, gc_no_gc_sleep_time, no_gc_sleep_time);
F2FS_RW_ATTR(GC_THREAD, f2fs_gc_kthread, gc_idle, gc_idle);
F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, reclaim_segments, rec_prefree_segments);
F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, max_small_discards, max_discards);
+F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, batched_trim_sections, trim_sections);
F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, ipu_policy, ipu_policy);
F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, min_ipu_util, min_ipu_util);
F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, min_fsync_blocks, min_fsync_blocks);
@@ -210,6 +211,7 @@ static struct attribute *f2fs_attrs[] = {
ATTR_LIST(gc_idle),
ATTR_LIST(reclaim_segments),
ATTR_LIST(max_small_discards),
+ ATTR_LIST(batched_trim_sections),
ATTR_LIST(ipu_policy),
ATTR_LIST(min_ipu_util),
ATTR_LIST(min_fsync_blocks),
--
2.1.1


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