Messages in this thread Patch in this message | | | Date | Sun, 15 Jul 2018 12:13:08 +0900 | From | Jaegeuk Kim <> | Subject | Re: [PATCH v2] f2fs: split discard command in prior to block layer |
| |
On 07/15, Chao Yu wrote: > Hi Jaegeuk, > > On 2018/7/15 9:27, Jaegeuk Kim wrote: > > On 07/08, Chao Yu wrote: > >> From: Chao Yu <yuchao0@huawei.com> > >> > >> Some devices has small max_{hw,}discard_sectors, so that in > >> __blkdev_issue_discard(), one big size discard bio can be split > >> into multiple small size discard bios, result in heavy load in IO > >> scheduler and device, which can hang other sync IO for long time. > >> > >> Now, f2fs is trying to control discard commands more elaboratively, > >> in order to make less conflict in between discard IO and user IO > >> to enhance application's performance, so in this patch, we will > >> split discard bio in f2fs in prior to in block layer to reduce > >> issuing multiple discard bios in a short time. > > > > Can we just change __submit_discard_cmd() to submit the large candidate > > partially and adjust lstart in the original candidate? > > Yep, could you check __submit_discard_cmd() implementation below? Does that > match the thoughts from you? > > Thanks, > > > > >> > >> Signed-off-by: Chao Yu <yuchao0@huawei.com> > >> --- > >> v2: > >> - change to split discard command entry before submission. > >> fs/f2fs/f2fs.h | 13 +++--- > >> fs/f2fs/segment.c | 117 +++++++++++++++++++++++++++++++++++++----------------- > >> 2 files changed, 86 insertions(+), 44 deletions(-) > >> > >> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > >> index c48b655d5d8d..359526d88d3f 100644 > >> --- a/fs/f2fs/f2fs.h > >> +++ b/fs/f2fs/f2fs.h > >> @@ -178,7 +178,6 @@ enum { > >> > >> #define MAX_DISCARD_BLOCKS(sbi) BLKS_PER_SEC(sbi) > >> #define DEF_MAX_DISCARD_REQUEST 8 /* issue 8 discards per round */ > >> -#define DEF_MAX_DISCARD_LEN 512 /* Max. 2MB per discard */ > >> #define DEF_MIN_DISCARD_ISSUE_TIME 50 /* 50 ms, if exists */ > >> #define DEF_MID_DISCARD_ISSUE_TIME 500 /* 500 ms, if device busy */ > >> #define DEF_MAX_DISCARD_ISSUE_TIME 60000 /* 60 s, if no candidates */ > >> @@ -709,22 +708,22 @@ static inline void set_extent_info(struct extent_info *ei, unsigned int fofs, > >> } > >> > >> static inline bool __is_discard_mergeable(struct discard_info *back, > >> - struct discard_info *front) > >> + struct discard_info *front, unsigned int max_len) > >> { > >> return (back->lstart + back->len == front->lstart) && > >> - (back->len + front->len < DEF_MAX_DISCARD_LEN); > >> + (back->len + front->len <= max_len); > >> } > >> > >> static inline bool __is_discard_back_mergeable(struct discard_info *cur, > >> - struct discard_info *back) > >> + struct discard_info *back, unsigned int max_len) > >> { > >> - return __is_discard_mergeable(back, cur); > >> + return __is_discard_mergeable(back, cur, max_len); > >> } > >> > >> static inline bool __is_discard_front_mergeable(struct discard_info *cur, > >> - struct discard_info *front) > >> + struct discard_info *front, unsigned int max_len) > >> { > >> - return __is_discard_mergeable(cur, front); > >> + return __is_discard_mergeable(cur, front, max_len); > >> } > >> > >> static inline bool __is_extent_mergeable(struct extent_info *back, > >> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > >> index f7f56dd091b4..cbf8f3f9a8e7 100644 > >> --- a/fs/f2fs/segment.c > >> +++ b/fs/f2fs/segment.c > >> @@ -966,17 +966,24 @@ static void __init_discard_policy(struct f2fs_sb_info *sbi, > >> } > >> } > >> > >> -
===================== BEGIN
> >> +static void __update_discard_tree_range(struct f2fs_sb_info *sbi, > >> + struct block_device *bdev, block_t lstart, > >> + block_t start, block_t len); > >> /* 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, > >> - struct discard_cmd *dc) > >> + struct discard_cmd *dc, > >> + unsigned int *issued) > >> { > >> + struct block_device *bdev = dc->bdev; > >> + struct request_queue *q = bdev_get_queue(bdev); > >> + unsigned int max_discard_blocks = > >> + SECTOR_TO_BLOCK(q->limits.max_discard_sectors); > >> struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info; > >> struct list_head *wait_list = (dpolicy->type == DPOLICY_FSTRIM) ? > >> &(dcc->fstrim_list) : &(dcc->wait_list); > >> - struct bio *bio = NULL; > >> int flag = dpolicy->sync ? REQ_SYNC : 0; > >> + block_t lstart, start, len, total_len; > >> > >> if (dc->state != D_PREP) > >> return; > >> @@ -984,30 +991,63 @@ static void __submit_discard_cmd(struct f2fs_sb_info *sbi, > >> if (is_sbi_flag_set(sbi, SBI_NEED_FSCK)) > >> return; > >> > >> - trace_f2fs_issue_discard(dc->bdev, dc->start, dc->len); > >> - > >> - dc->error = __blkdev_issue_discard(dc->bdev, > >> - SECTOR_FROM_BLOCK(dc->start), > >> - SECTOR_FROM_BLOCK(dc->len), > >> - GFP_NOFS, 0, &bio); > >> - if (!dc->error) { > >> - /* should keep before submission to avoid D_DONE right away */ > >> - dc->state = D_SUBMIT; > >> - atomic_inc(&dcc->issued_discard); > >> - atomic_inc(&dcc->issing_discard); > >> - if (bio) { > >> - bio->bi_private = dc; > >> - bio->bi_end_io = f2fs_submit_discard_endio; > >> - bio->bi_opf |= flag; > >> - submit_bio(bio); > >> - list_move_tail(&dc->list, wait_list); > >> - __check_sit_bitmap(sbi, dc->start, dc->start + dc->len); > >> - > >> - f2fs_update_iostat(sbi, FS_DISCARD, 1); > >> + trace_f2fs_issue_discard(bdev, dc->start, dc->len); > >> + > >> + lstart = dc->lstart; > >> + start = dc->start; > >> + len = dc->len; > >> + total_len = len; > >> + > >> + while (total_len && *issued < dpolicy->max_requests) { > >> + struct bio *bio = NULL; > >> + > >> + if (len > max_discard_blocks) > >> + len = max_discard_blocks; > >> + > >> + dc->error = __blkdev_issue_discard(bdev, > >> + SECTOR_FROM_BLOCK(start), > >> + SECTOR_FROM_BLOCK(len), > >> + GFP_NOFS, 0, &bio); > >> + if (!dc->error) { > >> + /* > >> + * should keep before submission to avoid D_DONE > >> + * right away > >> + */ > >> + dc->state = D_SUBMIT; > >> + dc->len = len; > >> + atomic_inc(&dcc->issued_discard); > >> + atomic_inc(&dcc->issing_discard); > >> + if (bio) { > >> + bio->bi_private = dc; > >> + bio->bi_end_io = f2fs_submit_discard_endio; > >> + bio->bi_opf |= flag; > >> + submit_bio(bio); > >> + list_move_tail(&dc->list, wait_list); > >> + __check_sit_bitmap(sbi, dc->start, > >> + dc->start + dc->len); > >> + > >> + f2fs_update_iostat(sbi, FS_DISCARD, 1); > >> + } > >> + } else { > >> + __remove_discard_cmd(sbi, dc);
Keep the original one, since it's partially failed?
> >> + return; > >> + } > >> + lstart += len; > >> + start += len; > >> + total_len -= len; > >> + len = total_len; > >> + (*issued)++; > >> + > >> + if (len) { > >> + __update_discard_tree_range(sbi, bdev, lstart, > >> + start, len);
Do we really need this? We already grabbed one candidate which was not merged well.
> >> + dc = (struct discard_cmd *)f2fs_lookup_rb_tree( > >> + &dcc->root, NULL, lstart); > >> + f2fs_bug_on(sbi, !dc); > >> } > >> - } else { > >> - __remove_discard_cmd(sbi, dc); > >> } > >> + > >> + return; > >> }
======================= END
> >> > >> static struct discard_cmd *__insert_discard_tree(struct f2fs_sb_info *sbi, > >> @@ -1088,10 +1128,11 @@ static void __update_discard_tree_range(struct f2fs_sb_info *sbi, > >> struct discard_cmd *dc; > >> struct discard_info di = {0}; > >> struct rb_node **insert_p = NULL, *insert_parent = NULL; > >> + struct request_queue *q = bdev_get_queue(bdev); > >> + unsigned int max_discard_blocks = > >> + SECTOR_TO_BLOCK(q->limits.max_discard_sectors); > >> block_t end = lstart + len; > >> > >> - mutex_lock(&dcc->cmd_lock); > >> - > >> dc = (struct discard_cmd *)f2fs_lookup_rb_tree_ret(&dcc->root, > >> NULL, lstart, > >> (struct rb_entry **)&prev_dc, > >> @@ -1131,7 +1172,8 @@ static void __update_discard_tree_range(struct f2fs_sb_info *sbi, > >> > >> if (prev_dc && prev_dc->state == D_PREP && > >> prev_dc->bdev == bdev && > >> - __is_discard_back_mergeable(&di, &prev_dc->di)) { > >> + __is_discard_back_mergeable(&di, &prev_dc->di, > >> + max_discard_blocks)) { > >> prev_dc->di.len += di.len; > >> dcc->undiscard_blks += di.len; > >> __relocate_discard_cmd(dcc, prev_dc); > >> @@ -1142,7 +1184,8 @@ static void __update_discard_tree_range(struct f2fs_sb_info *sbi, > >> > >> if (next_dc && next_dc->state == D_PREP && > >> next_dc->bdev == bdev && > >> - __is_discard_front_mergeable(&di, &next_dc->di)) { > >> + __is_discard_front_mergeable(&di, &next_dc->di, > >> + max_discard_blocks)) { > >> next_dc->di.lstart = di.lstart; > >> next_dc->di.len += di.len; > >> next_dc->di.start = di.start; > >> @@ -1165,8 +1208,6 @@ static void __update_discard_tree_range(struct f2fs_sb_info *sbi, > >> node = rb_next(&prev_dc->rb_node); > >> next_dc = rb_entry_safe(node, struct discard_cmd, rb_node); > >> } > >> - > >> - mutex_unlock(&dcc->cmd_lock); > >> } > >> > >> static int __queue_discard_cmd(struct f2fs_sb_info *sbi, > >> @@ -1181,7 +1222,9 @@ static int __queue_discard_cmd(struct f2fs_sb_info *sbi, > >> > >> blkstart -= FDEV(devi).start_blk; > >> } > >> + mutex_lock(&SM_I(sbi)->dcc_info->cmd_lock); > >> __update_discard_tree_range(sbi, bdev, lblkstart, blkstart, blklen); > >> + mutex_unlock(&SM_I(sbi)->dcc_info->cmd_lock); > >> return 0; > >> } > >> > >> @@ -1220,9 +1263,9 @@ static unsigned int __issue_discard_cmd_orderly(struct f2fs_sb_info *sbi, > >> } > >> > >> dcc->next_pos = dc->lstart + dc->len; > >> - __submit_discard_cmd(sbi, dpolicy, dc); > >> + __submit_discard_cmd(sbi, dpolicy, dc, &issued); > >> > >> - if (++issued >= dpolicy->max_requests) > >> + if (issued >= dpolicy->max_requests) > >> break; > >> next: > >> node = rb_next(&dc->rb_node); > >> @@ -1277,9 +1320,9 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi, > >> break; > >> } > >> > >> - __submit_discard_cmd(sbi, dpolicy, dc); > >> + __submit_discard_cmd(sbi, dpolicy, dc, &issued); > >> > >> - if (++issued >= dpolicy->max_requests) > >> + if (issued >= dpolicy->max_requests) > >> break; > >> } > >> blk_finish_plug(&plug); > >> @@ -2475,9 +2518,9 @@ static unsigned int __issue_discard_cmd_range(struct f2fs_sb_info *sbi, > >> goto skip; > >> } > >> > >> - __submit_discard_cmd(sbi, dpolicy, dc); > >> + __submit_discard_cmd(sbi, dpolicy, dc, &issued); > >> > >> - if (++issued >= dpolicy->max_requests) { > >> + if (issued >= dpolicy->max_requests) { > >> start = dc->lstart + dc->len; > >> > >> blk_finish_plug(&plug); > >> -- > >> 2.16.2.17.g38e79b1fd
| |