Hi Chao, On Thu, Jan 29, 2015 at 08:38:30PM +0800, Chao Yu wrote: > Hi Jaegeuk, > > > -----Original Message----- > > From: [email protected] > > [mailto:[email protected]] On > > Behalf Of Jaegeuk Kim > > Sent: Wednesday, January 28, 2015 7:32 AM > > To: [email protected]; [email protected]; > > [email protected] > > 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?
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. Thanks, > > Thanks, > > > > > Signed-off-by: Jaegeuk Kim <[email protected]> > > --- > > 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 > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > > the body of a message to [email protected] > > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
