* [PATCH] f2fs: merge WRITE bio into previous WRITE_SYNC @ 2016-08-27 0:53 Jaegeuk Kim 2016-09-02 7:33 ` Chao Yu 0 siblings, 1 reply; 6+ messages in thread From: Jaegeuk Kim @ 2016-08-27 0:53 UTC (permalink / raw) To: linux-kernel, linux-fsdevel, linux-f2fs-devel; +Cc: Jaegeuk Kim This can avoid bio splits due to different op_flags. Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> --- 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); -- 2.8.3 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] f2fs: merge WRITE bio into previous WRITE_SYNC 2016-08-27 0:53 [PATCH] f2fs: merge WRITE bio into previous WRITE_SYNC Jaegeuk Kim @ 2016-09-02 7:33 ` Chao Yu 2016-09-02 18:36 ` Jaegeuk Kim 0 siblings, 1 reply; 6+ messages in thread From: Chao Yu @ 2016-09-02 7:33 UTC (permalink / raw) To: Jaegeuk Kim, linux-kernel, linux-fsdevel, linux-f2fs-devel 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. Thanks, > > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> > --- > 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); > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] f2fs: merge WRITE bio into previous WRITE_SYNC 2016-09-02 7:33 ` Chao Yu @ 2016-09-02 18:36 ` Jaegeuk Kim 2016-09-07 14:12 ` [f2fs-dev] " Chao Yu 0 siblings, 1 reply; 6+ messages in thread From: Jaegeuk Kim @ 2016-09-02 18:36 UTC (permalink / raw) To: Chao Yu; +Cc: linux-kernel, linux-fsdevel, linux-f2fs-devel 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@kernel.org> > > --- > > 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); > > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [f2fs-dev] [PATCH] f2fs: merge WRITE bio into previous WRITE_SYNC 2016-09-02 18:36 ` Jaegeuk Kim @ 2016-09-07 14:12 ` Chao Yu 2016-09-08 0:26 ` Jaegeuk Kim 0 siblings, 1 reply; 6+ messages in thread From: Chao Yu @ 2016-09-07 14:12 UTC (permalink / raw) To: Jaegeuk Kim, Chao Yu; +Cc: linux-fsdevel, linux-kernel, linux-f2fs-devel On 2016/9/3 2:36, Jaegeuk Kim wrote: > 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 Hmm.. I'm worry about the opposite case: user triggers small WRITE_SYNC IO periodically, meanwhile there are big number of WRITE, with our new approach, actually we will increase the number of synchronous WRITE IO obviously because we will mix ASYNC/SYNC WRITE into bio cache intensively more than before since we drop writepages mutexlock. So I'm afread the result is that it will mislead scheduling of block layer. > 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. I thinks this is related to writeback / blocklayer / cgroup subsystem which use this tag frequently, maybe we should Cc their's mailing list for more opinion... What's your opinion? :) thanks, > > Thanks, > >> >> Thanks, >> >>> >>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> >>> --- >>> 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); >>> > > ------------------------------------------------------------------------------ > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [f2fs-dev] [PATCH] f2fs: merge WRITE bio into previous WRITE_SYNC 2016-09-07 14:12 ` [f2fs-dev] " Chao Yu @ 2016-09-08 0:26 ` Jaegeuk Kim 2016-09-08 16:09 ` Chao Yu 0 siblings, 1 reply; 6+ messages in thread From: Jaegeuk Kim @ 2016-09-08 0:26 UTC (permalink / raw) To: Chao Yu; +Cc: Chao Yu, linux-fsdevel, linux-kernel, linux-f2fs-devel On Wed, Sep 07, 2016 at 10:12:17PM +0800, Chao Yu wrote: > On 2016/9/3 2:36, Jaegeuk Kim wrote: > > 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 > > Hmm.. I'm worry about the opposite case: user triggers small WRITE_SYNC IO > periodically, meanwhile there are big number of WRITE, with our new approach, > actually we will increase the number of synchronous WRITE IO obviously because > we will mix ASYNC/SYNC WRITE into bio cache intensively more than before since > we drop writepages mutexlock. So I'm afread the result is that it will mislead > scheduling of block layer. > > > 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. > > I thinks this is related to writeback / blocklayer / cgroup subsystem which use > this tag frequently, maybe we should Cc their's mailing list for more opinion... Except cgroup, since we do not support it yet. :P Anyway, I think we'd better verify the effect of this for a while. For example, I'm able to write a simple program to measure fsync latency while a bunch of buffered writes. Meanwhile, I'll put it back to the end of dev-test repo. :) Thanks, > > What's your opinion? :) > > thanks, > > > > > Thanks, > > > >> > >> Thanks, > >> > >>> > >>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> > >>> --- > >>> 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); > >>> > > > > ------------------------------------------------------------------------------ > > _______________________________________________ > > Linux-f2fs-devel mailing list > > Linux-f2fs-devel@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [f2fs-dev] [PATCH] f2fs: merge WRITE bio into previous WRITE_SYNC 2016-09-08 0:26 ` Jaegeuk Kim @ 2016-09-08 16:09 ` Chao Yu 0 siblings, 0 replies; 6+ messages in thread From: Chao Yu @ 2016-09-08 16:09 UTC (permalink / raw) To: Jaegeuk Kim; +Cc: Chao Yu, linux-fsdevel, linux-kernel, linux-f2fs-devel On 2016/9/8 8:26, Jaegeuk Kim wrote: > On Wed, Sep 07, 2016 at 10:12:17PM +0800, Chao Yu wrote: >> On 2016/9/3 2:36, Jaegeuk Kim wrote: >>> 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 >> >> Hmm.. I'm worry about the opposite case: user triggers small WRITE_SYNC IO >> periodically, meanwhile there are big number of WRITE, with our new approach, >> actually we will increase the number of synchronous WRITE IO obviously because >> we will mix ASYNC/SYNC WRITE into bio cache intensively more than before since >> we drop writepages mutexlock. So I'm afread the result is that it will mislead >> scheduling of block layer. >> >>> 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. >> >> I thinks this is related to writeback / blocklayer / cgroup subsystem which use >> this tag frequently, maybe we should Cc their's mailing list for more opinion... > > Except cgroup, since we do not support it yet. :P Yeap. > > Anyway, I think we'd better verify the effect of this for a while. > For example, I'm able to write a simple program to measure fsync latency while > a bunch of buffered writes. > Meanwhile, I'll put it back to the end of dev-test repo. :) Sounds good plan. Hoping we will not suffer from regression here. ;) Thanks, > > Thanks, > >> >> What's your opinion? :) >> >> thanks, >> >>> >>> Thanks, >>> >>>> >>>> Thanks, >>>> >>>>> >>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> >>>>> --- >>>>> 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); >>>>> >>> >>> ------------------------------------------------------------------------------ >>> _______________________________________________ >>> Linux-f2fs-devel mailing list >>> Linux-f2fs-devel@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel >>> ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2016-09-08 16:09 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2016-08-27 0:53 [PATCH] f2fs: merge WRITE bio into previous WRITE_SYNC Jaegeuk Kim 2016-09-02 7:33 ` Chao Yu 2016-09-02 18:36 ` Jaegeuk Kim 2016-09-07 14:12 ` [f2fs-dev] " Chao Yu 2016-09-08 0:26 ` Jaegeuk Kim 2016-09-08 16:09 ` Chao Yu
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