Messages in this thread | | | Date | Sun, 15 Jul 2018 10:27:00 +0900 | From | Jaegeuk Kim <> | Subject | Re: [PATCH v2] f2fs: split discard command in prior to block layer |
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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?
> > 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, > } > } > > - > +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); > + return; > + } > + lstart += len; > + start += len; > + total_len -= len; > + len = total_len; > + (*issued)++; > + > + if (len) { > + __update_discard_tree_range(sbi, bdev, lstart, > + start, len); > + dc = (struct discard_cmd *)f2fs_lookup_rb_tree( > + &dcc->root, NULL, lstart); > + f2fs_bug_on(sbi, !dc); > } > - } else { > - __remove_discard_cmd(sbi, dc); > } > + > + return; > } > > 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
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