On Thu, 23.04.2009 at 19:40:34 +0200, Thomas Pfaff <[email protected]> wrote: > On Thu, 23 Apr 2009 17:25:57 +0200 Jan Stary <[email protected]> wrote: > > On Apr 23 18:09:55, Thomas Pfaff wrote: > > > First on Ubuntu: > > > /dev/sda2 on / type ext3 (rw,relatime,errors=remount-ro) > > > ~$ time (tar -zxf ports.tar.gz && sync) > > > real 0m47.784s > > > user 0m1.576s > > > sys 0m5.024s
47.78 seconds wall clock time > > > Then the same commands on OpenBSD: > > > /dev/wd0k on /home type ffs (local, nodev, nosuid, softdep) > > > $ time (tar -zxf ports.tar.gz && sync) > > > 1m2.62s real 0m1.15s user 0m7.15s system ~ 1 minute 2.5 seconds wall clock time > > So you have ~52 seconds on ext3 mounted 'realtime' (whatever that means), > > versus ~63 seconds on ffs mounted with 'softdep'. > > What was the problem again? > > That I cannot get the job done in less than a minute on OpenBSD > while on Linux it takes only 18 seconds. This is a misconception, imho. Your test above shows that the performance difference is about 15 seconds, or roughly 25%. I can't see the 18 seconds anywhere except in your first email about your perceived performance for the task. It is imho useful to remember that Linux caches disk access much more aggressively than OpenBSD. So, in reality, you don't write that much faster to disk, but to RAM, and the OS flushes the buffers at it's own leisure, while you are working on something else. Which reminds me to ask what the state of having a UBC in OpenBSD is, please? -- Kind regards, --Toni++
