Hi Jaegeuk,
> -----Original Message-----
> From: linux-fsdevel-ow...@vger.kernel.org
> [mailto:linux-fsdevel-ow...@vger.kernel.org] On
> Behalf Of Jaegeuk Kim
> Sent: Wednesday, January 28, 2015 7:32 AM
> To: linux-kernel@vger.kernel.org; linux-fsde...@vger.kernel.org;
> linux-f2fs-de...@lists.sourceforge.net
> Cc: Jaegeuk Kim
> Subject: [PATCH 5/5] f2fs: introduce a batched trim
>
> This patch introduces a batched trimming feature, which submits split discard
> commands.
I didn't get it, why we should split discard commands. :(
Does smaller discarding for flash shows better performance or effect or safety?
Can you please explain more about this patch?
Thanks,
>
> Signed-off-by: Jaegeuk Kim <jaeg...@kernel.org>
> ---
> fs/f2fs/f2fs.h | 1 +
> fs/f2fs/segment.c | 15 ++++++++++-----
> 2 files changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index c0b83d6..ec4d16b 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -104,6 +104,7 @@ enum {
> CP_DISCARD,
> };
>
> +#define BATCHED_TRIM_SEGMENTS 10
> struct cp_control {
> int reason;
> __u64 trim_start;
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 31c4e57..6c9c784 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1066,14 +1066,19 @@ 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 + 1) {
> + cpc.trim_start = start_segno;
> + cpc.trim_end = min_t(unsigned int,
> + start_segno + BATCHED_TRIM_SEGMENTS, 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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