On Fri, Sep 02, 2016 at 03:33:33PM +0800, Chao Yu wrote: > Hi Jaegeuk, > > On 2016/8/27 8:53, Jaegeuk Kim wrote: > > This can avoid bio splits due to different op_flags. > > I thought about this, but I think this is not a good idea to increase merging > ratio of pages in bio. It breaks the rule of SYNC/ASYNC IO defined by system > which indicate degree of IO emergency, finally, some/more non-emergent IO will > treated as emergent one by IO scheduler, it will interrupt SYNC IOs in block > layer, more seriously, it may make real SYNC IO starvation. I understand your concern. Originally, I tried to avoid breaking a big WRITE_SYNC by a small number of WRITE. And, I thought new WRITE can be piggybacked into previous WRITE_SYNC. IMO, this happens very occassionally since previous pending bio should be WRITE_SYNC while a new request is WRITE. Even if this happens, the piggybacked size would not exceed over bio's max pages. If lots of WRITE come, we won't change at all. Thanks, > > Thanks, > > > > > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> > > --- > > fs/f2fs/data.c | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > > index 7c8e219..c7c2022 100644 > > --- a/fs/f2fs/data.c > > +++ b/fs/f2fs/data.c > > @@ -267,6 +267,11 @@ void f2fs_submit_page_mbio(struct f2fs_io_info *fio) > > > > down_write(&io->io_rwsem); > > > > + /* WRITE can be merged into previous WRITE_SYNC */ > > + if (io->bio && io->last_block_in_bio == fio->new_blkaddr - 1 && > > + io->fio.op == fio->op && io->fio.op_flags == WRITE_SYNC) > > + fio->op_flags = WRITE_SYNC; > > + > > if (io->bio && (io->last_block_in_bio != fio->new_blkaddr - 1 || > > (io->fio.op != fio->op || io->fio.op_flags != fio->op_flags))) > > __submit_merged_bio(io); > > -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
