Messages in this thread | | | Subject | Re: [PATCH v2] f2fs: split discard command in prior to block layer | From | Chao Yu <> | Date | Sun, 15 Jul 2018 09:32:35 +0800 |
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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, >> } >> } >> >> - >> +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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