Re: 2.6.6-mm5 oops mounting ext3 or reiserfs with -o barrier

[Jens Axboe <axboe@suse.de>]

On Sun, May 23 2004, Lorenzo Allegrucci wrote:
> On Sunday 23 May 2004 17:45, Jens Axboe wrote:
> > On Sun, May 23 2004, Lorenzo Allegrucci wrote:
> > > On Sunday 23 May 2004 12:03, Jens Axboe wrote:
> > > > Here's a rolled up updated version that tries to get async notification
> > > > of missing barrier support working as well. reiser currently doesn't
> > > > cope with that correctly (fails mount), ext3 seems to but gets stuck.
> > > > Andrew has that fixed already, I think :-)
> > > >
> > > > Lorenzo, can you test this on top of 2.6.6-mm5?
> > >
> > > Problem fixed, but there is some performance regression
> > >
> > > ext3 (default)
> > > untar		read		copy		remove
> > > 0m53.861s	0m24.942s	1m30.164s	0m20.664s
> > > 0m7.132s	0m1.191s	0m0.766s	0m0.076s
> > > 0m5.807s	0m3.345s	0m9.996s	0m1.719s
> > >
> > > ext3 (-o barrier=1)
> > > untar		read		copy		remove
> > > 0m52.117s	0m28.502s	1m51.153s	0m25.561s
> > > 0m7.231s	0m1.209s	0m0.738s	0m0.071s
> > > 0m6.117s	0m3.191s	0m9.347s	0m1.635s
> >
> > Not sure what you mean here
> 
> Untar, read, copy and remove the OpenOffice tarball, each test
> run with cold cache (mount/umount cycle).

I understand that, I just don't see how you can call it a regression.
It's a given that barrier will be slower.

> > but yes of course -o barrier=1 is going to 
> > be slower than default + write back caching. What you should compare is
> > without barrier support and hdparm -W0 /dev/hdX, if -o barrier=1 with
> > caching on is slower then that's a regression :-)
> 
> hdparm -W0 /dev/hda
> 
> ext3 (-o barrier=0)
> untar		read		copy		remove
> 1m55.190s	0m27.633s	2m19.072s	0m21.348s
> 0m7.081s	0m1.189s	0m0.724s	0m0.083s
> 0m6.502s	0m3.244s	0m9.715s	0m1.633s
> 
> ext3 (-o barrier=1)
> untar		read		copy		remove
> 1m55.358s	0m23.831s	2m16.674s	0m21.508s
> 0m7.153s	0m1.200s	0m0.748s	0m0.087s
> 0m6.775s	0m3.358s	0m9.985s	0m1.781s
> 
> 
> haparm -W1 /dev/hda
> 
> ext3 (-o barrier=0)
> untar		read		copy		remove
> 0m55.405s	0m26.230s	1m28.765s	0m20.766s
> 0m7.195s	0m1.199s	0m0.773s	0m0.081s
> 0m6.502s	0m3.359s	0m9.672s	0m1.868s
> 
> ext3 (-o barrier=1)
> untar		read		copy		remove
> 0m52.117s	0m28.502s	1m51.153s	0m25.561s
> 0m7.231s	0m1.209s	0m0.738s	0m0.071s
> 0m6.117s	0m3.191s	0m9.347s	0m1.635s

Your results look a bit over the map, how many runs are your averaging
for each one?

-- 
Jens Axboe