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Subject[PATCH] f2fs: issue discard commands proactively in high fs utilization
Date
In the high utilization like over 80%, we don't expect huge # of large discard
commands, but do many small pending discards which affects FTL GCs a lot.
Let's issue them in that case.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
fs/f2fs/f2fs.h | 3 +-
fs/f2fs/segment.c | 71 ++++++++++++++++++++++++++---------------------
2 files changed, 40 insertions(+), 34 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index e852ac9472c6..27231fe8a6b2 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -186,6 +186,7 @@ enum {
#define DEF_MAX_DISCARD_LEN 512 /* Max. 2MB per discard */
#define DEF_MIN_DISCARD_ISSUE_TIME 50 /* 50 ms, if exists */
#define DEF_MAX_DISCARD_ISSUE_TIME 60000 /* 60 s, if no candidates */
+#define DEF_DISCARD_URGENT_UTIL 80 /* do more discard over 80% */
#define DEF_CP_INTERVAL 60 /* 60 secs */
#define DEF_IDLE_INTERVAL 5 /* 5 secs */

@@ -2777,8 +2778,6 @@ int f2fs_flush_device_cache(struct f2fs_sb_info *sbi);
void destroy_flush_cmd_control(struct f2fs_sb_info *sbi, bool free);
void invalidate_blocks(struct f2fs_sb_info *sbi, block_t addr);
bool is_checkpointed_data(struct f2fs_sb_info *sbi, block_t blkaddr);
-void init_discard_policy(struct discard_policy *dpolicy, int discard_type,
- unsigned int granularity);
void drop_discard_cmd(struct f2fs_sb_info *sbi);
void stop_discard_thread(struct f2fs_sb_info *sbi);
bool f2fs_wait_discard_bios(struct f2fs_sb_info *sbi);
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 6e40e536dae0..8c1f7a6bf178 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -915,6 +915,38 @@ static void __check_sit_bitmap(struct f2fs_sb_info *sbi,
#endif
}

+static void __init_discard_policy(struct f2fs_sb_info *sbi,
+ struct discard_policy *dpolicy,
+ int discard_type, unsigned int granularity)
+{
+ /* common policy */
+ dpolicy->type = discard_type;
+ dpolicy->sync = true;
+ dpolicy->granularity = granularity;
+
+ dpolicy->max_requests = DEF_MAX_DISCARD_REQUEST;
+ dpolicy->io_aware_gran = MAX_PLIST_NUM;
+
+ if (discard_type == DPOLICY_BG) {
+ dpolicy->min_interval = DEF_MIN_DISCARD_ISSUE_TIME;
+ dpolicy->max_interval = DEF_MAX_DISCARD_ISSUE_TIME;
+ dpolicy->io_aware = true;
+ if (utilization(sbi) > DEF_DISCARD_URGENT_UTIL) {
+ dpolicy->granularity = 1;
+ dpolicy->max_interval = DEF_MIN_DISCARD_ISSUE_TIME;
+ }
+ } else if (discard_type == DPOLICY_FORCE) {
+ dpolicy->min_interval = DEF_MIN_DISCARD_ISSUE_TIME;
+ dpolicy->max_interval = DEF_MAX_DISCARD_ISSUE_TIME;
+ dpolicy->io_aware = false;
+ } else if (discard_type == DPOLICY_FSTRIM) {
+ dpolicy->io_aware = false;
+ } else if (discard_type == DPOLICY_UMOUNT) {
+ dpolicy->io_aware = false;
+ }
+}
+
+
/* this function is copied from blkdev_issue_discard from block/blk-lib.c */
static void __submit_discard_cmd(struct f2fs_sb_info *sbi,
struct discard_policy *dpolicy,
@@ -1278,9 +1310,9 @@ static void __wait_all_discard_cmd(struct f2fs_sb_info *sbi,
}

/* wait all */
- init_discard_policy(&dp, DPOLICY_FSTRIM, 1);
+ __init_discard_policy(sbi, &dp, DPOLICY_FSTRIM, 1);
__wait_discard_cmd_range(sbi, &dp, 0, UINT_MAX);
- init_discard_policy(&dp, DPOLICY_UMOUNT, 1);
+ __init_discard_policy(sbi, &dp, DPOLICY_UMOUNT, 1);
__wait_discard_cmd_range(sbi, &dp, 0, UINT_MAX);
}

@@ -1326,7 +1358,8 @@ bool f2fs_wait_discard_bios(struct f2fs_sb_info *sbi)
struct discard_policy dpolicy;
bool dropped;

- init_discard_policy(&dpolicy, DPOLICY_UMOUNT, dcc->discard_granularity);
+ __init_discard_policy(sbi, &dpolicy, DPOLICY_UMOUNT,
+ dcc->discard_granularity);
__issue_discard_cmd(sbi, &dpolicy);
dropped = __drop_discard_cmd(sbi);

@@ -1347,7 +1380,7 @@ static int issue_discard_thread(void *data)
set_freezable();

do {
- init_discard_policy(&dpolicy, DPOLICY_BG,
+ __init_discard_policy(sbi, &dpolicy, DPOLICY_BG,
dcc->discard_granularity);

wait_event_interruptible_timeout(*q,
@@ -1365,7 +1398,7 @@ static int issue_discard_thread(void *data)
dcc->discard_wake = 0;

if (sbi->gc_thread && sbi->gc_thread->gc_urgent)
- init_discard_policy(&dpolicy, DPOLICY_FORCE, 1);
+ __init_discard_policy(sbi, &dpolicy, DPOLICY_FORCE, 1);

sb_start_intwrite(sbi->sb);

@@ -1658,32 +1691,6 @@ void clear_prefree_segments(struct f2fs_sb_info *sbi, struct cp_control *cpc)
wake_up_discard_thread(sbi, false);
}

-void init_discard_policy(struct discard_policy *dpolicy,
- int discard_type, unsigned int granularity)
-{
- /* common policy */
- dpolicy->type = discard_type;
- dpolicy->sync = true;
- dpolicy->granularity = granularity;
-
- dpolicy->max_requests = DEF_MAX_DISCARD_REQUEST;
- dpolicy->io_aware_gran = MAX_PLIST_NUM;
-
- if (discard_type == DPOLICY_BG) {
- dpolicy->min_interval = DEF_MIN_DISCARD_ISSUE_TIME;
- dpolicy->max_interval = DEF_MAX_DISCARD_ISSUE_TIME;
- dpolicy->io_aware = true;
- } else if (discard_type == DPOLICY_FORCE) {
- dpolicy->min_interval = DEF_MIN_DISCARD_ISSUE_TIME;
- dpolicy->max_interval = DEF_MAX_DISCARD_ISSUE_TIME;
- dpolicy->io_aware = false;
- } else if (discard_type == DPOLICY_FSTRIM) {
- dpolicy->io_aware = false;
- } else if (discard_type == DPOLICY_UMOUNT) {
- dpolicy->io_aware = false;
- }
-}
-
static int create_discard_cmd_control(struct f2fs_sb_info *sbi)
{
dev_t dev = sbi->sb->s_bdev->bd_dev;
@@ -2442,7 +2449,7 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
start_block = START_BLOCK(sbi, start_segno);
end_block = START_BLOCK(sbi, min(cur_segno, end_segno) + 1);

- init_discard_policy(&dpolicy, DPOLICY_FSTRIM, cpc.trim_minlen);
+ __init_discard_policy(sbi, &dpolicy, DPOLICY_FSTRIM, cpc.trim_minlen);
__issue_discard_cmd_range(sbi, &dpolicy, start_block, end_block);
trimmed = __wait_discard_cmd_range(sbi, &dpolicy,
start_block, end_block);
--
2.17.0.441.gb46fe60e1d-goog
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