Re: 2.6.16-rc6-mm2: slow writes on reiser4.

[Laurent Riffard <laurent.riffard@free.fr>]

Le 29.03.2006 00:49, Philippe Gramoullé a écrit :
> Hello Laurent,
> 
> On Tue, 28 Mar 2006 22:19:01 +0200
> Laurent Riffard <laurent.riffard@free.fr> wrote:
> 
>   | These FS are quite similars. Now guess what ? I filled these FS with
>   |  dd.
>   | 
>   | Original FS
>   | ===========
>   | # sync
>   | # time dd if=/dev/zero of=toto bs=1M count=150
>   | 103+0 enregistrements lus.
>   | 102+0 enregistrements écrits.
>   | Command exited with non-zero status 1
> 
> Well, at least on my system , such a command exits with a 0 status

Oops ! I trimmed a line when I cut'n'paste. dd exits with the
message "Aucun espace disponible sur le périphérique" which means
"No space left on device".

> Also, not a single of your posts in this thread has this error except this one
> and the one below

Yes I somewhat changed my test. On the previous test, I dd'd 100M to
the FS.

As the original FS and its copy have different free space, writing
100M on each FS results in 3M free versus 30M free. I did this test
and I it takes about 2'20" versus 15". But I feared that one objects
"It's  because you have less free space on the first FS".

So I found more conclusive to write 150M and thus to fill up the 2 FS.

>   | 0.00user 2.94system 3:32.18elapsed 1%CPU (0avgtext+0avgdata
>   | 0maxresident)k
>   | # time sync
>   | 0inputs+0outputs (0major+279minor)pagefaults 0swaps
>   | 0.00user 0.01system 0:00.18elapsed 6%CPU (0avgtext+0avgdata
>   | 0maxresident)k
>   | 0inputs+0outputs (0major+191minor)pagefaults 0swaps
>   | 
>   | Copy FS
>   | =======
>   | # sync
>   | # time dd if=/dev/zero of=toto bs=1M count=150
>   | dd: écriture de `toto': Aucun espace disponible sur le périphérique
>   | 132+0 enregistrements lus.
>   | 131+0 enregistrements écrits.
>   | Command exited with non-zero status 1
> 
> Here, i can understand the "exited with non-zero status 1" as
> "Aucun espace disponible sur le périphérique" is french for 
> "No space left on device"

yes, see above.

>   | 0.00user 4.08system 0:15.95elapsed 25%CPU (0avgtext+0avgdata
>   | 0maxresident)k
>   | 0inputs+0outputs (1major+279minor)pagefaults 0swaps
>   | # time sync
>   | 0.00user 0.00system 0:00.17elapsed 0%CPU (0avgtext+0avgdata
>   | 0maxresident)k
>   | 0inputs+0outputs (0major+190minor)pagefaults 0swaps
>   | disk$
>   | 
>   | See ? 3'30" versus 16".
> 
> Are the 16" due to the fact that the above command exited earlier than it should have ?

No, (see above), both FS were filled up to 0M free space.

> Thanks,
> 
> Philippe
> 

Thanks for your comments. I hope this made it clear.

To be fair, you can see there is some differences between the 2 FS :
- the copy is larger than the original one : 995998 bytes vs
1003520, which is 0.75% larger.
- the original FS resides on an extended partition (/dev/hda8) while
the copy is on a logical volume (/dev/vglinux1/test). This LV is
hosted on /dev/hda4.

I hope these differences do not have a high impact on the results.
I'll try to dd of=/dev/hda8 if=/dev/vglinux1/test, and see if it
makes some differences when I dd a 100M file on the FS.
~~
laurent