On Saturday 20 January 2007 17:39, Flavio wrote: > 2007/1/20, Blaisorblade <[EMAIL PROTECTED]>: > > I.e. a SMP processor obviously, right? > > That's right! > > > UML does not support SMP, so it can use just one processor. This is the > > major slowdown case in your comparison. > > > > Compare make -j2 on the host and on the guest: there will still be some > > slowdown, but not such an high one. Possibly on the guest make -j1 could > > be better (it would be interesting). > > host # time make -j2 > real 1m54.358s > user 3m9.300s > sys 0m18.910s
Er, it seems that _I_ gave you a wrong suggestion - it is still using both processor (though not optimally), so "time make -j1" on _both_ the host and the guest is a fairer comparison. The confusion was born since on a uniprocessor machine it is usually suggested to use make -j2. However, make -j2 on a dual core will use both processors. > guest # time make -j2 > real 7m37.511s > user 2m32.770s > sys 0m23.200s > > guest # time make -j1 > real 7m41.003s > user 2m33.880s > sys 0m23.230s > > :-( ''' > : > > Also, the user time is less on UML. The fact that total time is higher is > > probably due to running with -j3 on a uniprocessor machine, and the fact > > that the user time is less is probably due to using gcc 3.3 rather than 4 > > (I seem to recall gcc 4 is slower in compilation than gcc 3). -- Inform me of my mistakes, so I can add them to my list! Paolo Giarrusso, aka Blaisorblade http://www.user-mode-linux.org/~blaisorblade Chiacchiera con i tuoi amici in tempo reale! http://it.yahoo.com/mail_it/foot/*http://it.messenger.yahoo.com ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user
