f2fs: introduce a batched trim

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.

Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index 6f9157f16725afdc58ae72fa0c8e9fe46d4fce47..2c4cc42006e8c92baad28fabfec3f3fd8ec3cff1 100644 (file)
--- 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 6758aa358475218ea9f2157b937175069320f120..dac11d7fef2744adb2b9ae185f9665b10d761be4 100644 (file)
--- 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 db1ff55de0bc9cc8f0a3806e2a7e5f6edc5a3681..337204dfc5cd3f5a4caca4b570645acdb97d5f18 100644 (file)
--- 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 */
+       unsigned 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 5ea57ec153d13ac028835535a292f1e998eb20b6..9f278d156d880f3153b9de18c008091a8cbc2b61 100644 (file)
--- 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 1e92c2ea6bc159da01796fe14992946dd7e532c7..f2fe666a6ea995a29d5aee3f228acaf75e6cf85a 100644 (file)
--- 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),