Hi Jaegeuk,
IMHO, it looks better user could decide the size of trim considering latency of trim.
Otherwise, additional checkpoints user doesn't want will occur.
Regards,
Changman
On Mon, Feb 02, 2015 at 03:29:25PM -0800, Jaegeuk Kim wrote:
> Change long from v1:
> o add description
> o change the # of batched segments suggested by Chao
> o make consistent for # of batched segments
>
> This patch introduces a batched trimming feature, which submits split discard
> commands.
>
> 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.
>
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> ---
> fs/f2fs/f2fs.h | 2 ++
> fs/f2fs/segment.c | 16 +++++++++++-----
> 2 files changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 8231a59..ec5e66f 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -105,6 +105,8 @@ enum {
> CP_DISCARD,
> };
>
> +#define BATCHED_TRIM_SEGMENTS(sbi) (((sbi)->segs_per_sec) << 5)
> +
> struct cp_control {
> int reason;
> __u64 trim_start;
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 5ea57ec..b85bb97 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1066,14 +1066,20 @@ 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 += BATCHED_TRIM_SEGMENTS(sbi)) {
> + cpc.trim_start = start_segno;
> + cpc.trim_end = min_t(unsigned int,
> + start_segno + BATCHED_TRIM_SEGMENTS (sbi) - 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;
> --
> 2.1.1
>
>
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