f2fs causes system stall

f2fs causes system stall

[Marc Dietrich]

Hi,

it took me a while to bisect a problem which causes my ARM (tegra2) netbook to 
frequently stall for 5-10 seconds when I enable EXA acceleration (opentegra 
experimental ddx). I can only guess that the offending commit 8618b88 "f2fs: 
fix not to write data pages on the page reclaiming path" somehow causes high 
kernel latencies which may interrupt/disturb the command stream to the gpu in 
this particular case. Reverting this commit fixes the problem. Any hints?

Regards,

Marc

Re: f2fs causes system stall

[Jaegeuk Kim]

Hi,

Thank you for the report.
When I veiwed the patch at a glance, it seems that reverting is not a
good way.

Instead, could you share the f2fs commit point that you're using?
Then, since I have a suspect for this issue, I'd like to write a patch
to test.

Thanks,

2014-04-24 (목), 00:00 +0200, Marc Dietrich:
> Hi,
> 
> it took me a while to bisect a problem which causes my ARM (tegra2) netbook to 
> frequently stall for 5-10 seconds when I enable EXA acceleration (opentegra 
> experimental ddx). I can only guess that the offending commit 8618b88 "f2fs: 
> fix not to write data pages on the page reclaiming path" somehow causes high 
> kernel latencies which may interrupt/disturb the command stream to the gpu in 
> this particular case. Reverting this commit fixes the problem. Any hints?
> 
> Regards,
> 
> Marc
> 

-- 
Jaegeuk Kim
Samsung

Re: f2fs causes system stall

[Marc Dietrich]

Hi,

On Thu, 24 Apr 2014 08:54:30 +0900
Jaegeuk Kim <jaegeuk.kim@samsung.com> wrote:
> Thank you for the report.
> When I veiwed the patch at a glance, it seems that reverting is not a
> good way.
> 
> Instead, could you share the f2fs commit point that you're using?
> Then, since I have a suspect for this issue, I'd like to write a patch
> to test.

patch against linus master is ok for me. I'm happy to test your patch.

> 2014-04-24 (목), 00:00 +0200, Marc Dietrich:
> > Hi,
> > 
> > it took me a while to bisect a problem which causes my ARM (tegra2) netbook to 
> > frequently stall for 5-10 seconds when I enable EXA acceleration (opentegra 
> > experimental ddx). I can only guess that the offending commit 8618b88 "f2fs: 
> > fix not to write data pages on the page reclaiming path" somehow causes high 
> > kernel latencies which may interrupt/disturb the command stream to the gpu in 
> > this particular case. Reverting this commit fixes the problem. Any hints?

Regards,

Marc

Re: f2fs causes system stall

[Jaegeuk Kim]

Thank you very much.

Could you test the following patch?

---
 fs/f2fs/data.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 150c12a..0147de7 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -833,6 +833,8 @@ out:
 	unlock_page(page);
 	if (need_balance_fs)
 		f2fs_balance_fs(sbi);
+	if (wbc->for_reclaim)
+		f2fs_submit_merged_bio(sbi, DATA, WRITE);
 	return 0;
 
 redirty_out:
-- 
1.8.4.474.g128a96c


-- 
Jaegeuk Kim
Samsung

Re: f2fs causes system stall

[Marc Dietrich]

On Fri, 25 Apr 2014 08:33:56 +0900
Jaegeuk Kim <jaegeuk.kim@samsung.com> wrote:

> Thank you very much.
> 
> Could you test the following patch?

seems to be fixed now. Thanks!

Marc


> ---
>  fs/f2fs/data.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 150c12a..0147de7 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -833,6 +833,8 @@ out:
>  	unlock_page(page);
>  	if (need_balance_fs)
>  		f2fs_balance_fs(sbi);
> +	if (wbc->for_reclaim)
> +		f2fs_submit_merged_bio(sbi, DATA, WRITE);
>  	return 0;
>  
>  redirty_out:
> -- 
> 1.8.4.474.g128a96c
> 
> 
> -- 
> Jaegeuk Kim
> Samsung
> 


-- 
Marc Dietrich <marvin24@gmx.de>

Re: f2fs causes system stall

[Marc Dietrich]

Jaeguek,

Am Freitag, 25. April 2014, 14:39:00 schrieb Marc Dietrich:
> On Fri, 25 Apr 2014 08:33:56 +0900
> 
> Jaegeuk Kim <jaegeuk.kim@samsung.com> wrote:
> > Thank you very much.
> > 
> > Could you test the following patch?
> 
> seems to be fixed now. Thanks!

are you planing to submit this fix ("f2fs: submit bio at the reclaim path") to 
3.15?

Thanks,

Marc

> 
> > ---
> > 
> >  fs/f2fs/data.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > index 150c12a..0147de7 100644
> > --- a/fs/f2fs/data.c
> > +++ b/fs/f2fs/data.c
> > 
> > @@ -833,6 +833,8 @@ out:
> >  	unlock_page(page);
> >  	if (need_balance_fs)
> >  	
> >  		f2fs_balance_fs(sbi);
> > 
> > +	if (wbc->for_reclaim)
> > +		f2fs_submit_merged_bio(sbi, DATA, WRITE);
> > 
> >  	return 0;
> >  
> >  redirty_out: