Yep. By eliminating the Linux init, boot time of a single CPU dropped from ~12 hours down to ~2. I tried applying the patches from the M5 Linux patch queue, and a couple for v2.6.27 worked out of the box. From there, I ported a delay loop patch (maybe two?) from the queue for x86_64, and that cut boot time down to about 70 minutes (for perspective, ALPHA_FS boot time on this machine takes about 11 minutes). I think there are some more patches in the queue that might also help the boot time, but they probably also need to be ported. Once I got down to a tolerable iteration time, I moved on to other things (like checkpointing, which will hopefully be ready soon :] ). I can dig out my build configs and give some more gory detail on the patches if anyone's interested. I'm not sure when I will have time to circle back on the patches. Joel
On Sun, Aug 15, 2010 at 11:49 PM, Gabe Black <gbl...@eecs.umich.edu> wrote: > nathan binkert wrote: > >> Aside from building a Linux kernel, you will need to build and > configure a > >> disk image as well, which is also a fair amount of work. I've found > that, > >> unfortunately due to the long simulation time of Linux boot up, the > >> iteration time to debug the X86_FS bootup is quite long. > >> > > > > Really, bootup is quite long? It's pretty fast on Alpha and I > > wouldn't expect that much more to be going on in x86. There are a lot > > of delay loops during bootup that slow things down. Have you elided > > all of those? > > > > Nate > > _______________________________________________ > > m5-dev mailing list > > m5-...@m5sim.org > > http://m5sim.org/mailman/listinfo/m5-dev > > > > Just to clarify, multicore bootup of an unmodified kernel -does- work, > at least in the limited circumstances I've tried it (atomic CPU, a > particular version of Linux, etc.). Please correct me if I'm wrong, > Joel, but I'm guessing you mean multicore support with your modified > kernel, right? There are patches out there which cut out the delay > loops, but I don't know if they've actually made it anywhere people can > get at them. I wasn't confident they were correct at the time since I > didn't know how to really test them thoroughly, so I never pushed them > upstream. They do make a noticeable difference, but it's not night and > day. If you boot Linux to the end of kernel initialization where it > starts the first user process, the boot time isn't too bad. If you leave > in all the init scripts that start up the various services turned on by > default in a stage 3 Gentoo image, the time to a login is quite > substantial. If that's what you're doing, you could save *alot* of time > by getting rid of the unnecessary scripts. I've never attempted this > myself, but I'm guessing it isn't too bad. > > Gabe > _______________________________________________ > m5-users mailing list > m5-users@m5sim.org > http://m5sim.org/cgi-bin/mailman/listinfo/m5-users > -- Joel Hestness PhD Student, Computer Architecture Dept. of Computer Science, University of Texas - Austin http://www.cs.utexas.edu/~hestness
_______________________________________________ m5-users mailing list m5-users@m5sim.org http://m5sim.org/cgi-bin/mailman/listinfo/m5-users
