hi,

yea, there is some performance work remaining to be done for softdeps
in the UBC world.  (and other areas too, but this is one of the more
noticable ones.)  I haven't had a chance to investigate yet,
but it's on my list of things to do.

-Chuck


On Wed, Jan 03, 2001 at 02:46:57AM +0900, IWAMOTO Toshihiro wrote:
> On the other day, I've noticed rather significant drop in tarball
> extraction spped with UBC.
> 
> Here are some figures. Tests are done on a softdep ffs with a 433MHz
> Celeron machine which has 256MB of RAM.
> 
> With an 1.5K kernel with 50MB of bufcache (without UBC):
>     > tar zxf /usr/pkgsrc/distfiles/emacs-20.7.tar.gz 
>     4.438u 3.049s 0:19.26 38.7%     0+0k 424+8202io 58pf+0w
>     > time tar zxf /usr/pkgsrc/distfiles/emacs-20.6.tar.gz
>     4.565u 2.961s 0:14.27 52.6%     0+0k 381+8248io 2pf+0w
>     > rm -rf emacs-20.[67]
>     > time tar zxf /usr/pkgsrc/distfiles/emacs-20.6.tar.gz
>     4.610u 3.061s 0:10.46 73.3%     0+0k 95+8191io 0pf+0w
>     > time tar zxf /usr/pkgsrc/distfiles/emacs-20.7.tar.gz
>     4.567u 2.993s 0:13.52 55.8%     0+0k 361+8214io 0pf+0w
>     > rm -rf emacs-20.[67]
>     > time tar zxf /usr/pkgsrc/distfiles/emacs-20.7.tar.gz
>     4.541u 2.794s 0:12.60 58.1%     0+0k 92+8206io 0pf+0w
> 
> With an 1.5N kernel with 40MB of bufcache (with UBC):
>     > time tar zxf /usr/pkgsrc/distfiles/emacs-20.7.tar.gz
>     4.459u 5.165s 0:43.43 22.1%     0+0k 141+385io 34pf+0w
>     > time tar zxf /usr/pkgsrc/distfiles/emacs-20.6.tar.gz
>     4.517u 5.087s 0:46.41 20.6%     0+0k 109+396io 1pf+0w
>     > rm -rf emacs-20.[67]
>     > time tar zxf /usr/pkgsrc/distfiles/emacs-20.7.tar.gz
>     4.607u 5.132s 0:26.44 36.8%     0+0k 2+358io 0pf+0w
>     > time tar zxf /usr/pkgsrc/distfiles/emacs-20.6.tar.gz
>     4.506u 5.277s 0:45.34 21.5%     0+0k 2+407io 0pf+0w	
> 
> 
> If you run iostat while extracting tarballs, you might see the likely
> cause of speed drop.  Without UBC, about 40k bytes are written per
> transfer.  With UBC, writes are done in smaller chunks (7~9kB per
> transfer).
> 
> I'm not sure how much this speed drop affects normal usage.  Also I'm
> not sure if this can be easily fixed.  I'm posting this message here
> in the hope that someone takes look at this issue...
> 
> --
> IWAMOTO Toshihiro