Messages in this thread | | | Date | Mon, 23 Mar 1998 09:36:01 +0100 | From | Kurt Garloff <> | Subject | Re: SMP speed on 6x86 UPt |
| |
> > Why that? It's the normal way every the CPU starts to boot the kernel. > > Do other processors than second and later _intel_ processors have null > > in %bx for some reason ? > > Ok the intel stuff has to boot the other CPU's in real mode (no I dont know > why intel did this either). We do a real mode start up in low memory using > the base of that CPU's kernel stack and jump into protected mode and to > the kernel entry code. the lock variable is used to detected 2nd or later > CPUs (bad things occur if CPU#2 also clears the BSS for example..)
You're right, %bx is cleared in setup.S and only non-zero, if head.S is entered through trampoline.S.
> > Sorry, I don't understand what you want to tell me here. I'd like to have an > > official SMP kernel running on my UP 6x86, that's why I try to find a real > > solution for this. > > Im wondering if its something else like alignments
Not sure. The 6x86 is pretty much independent of alignments (compared to Pentium or PPro), so I don't think it's an alignment matter.
Forget about the CR4 thing. Maybe I was booting the wrong kernel and was believing the jump did make the change. So my SMP kernel still suffers the slowdown. I believe, it's something like BTB or L1 deactivation that causes the slowdown. The Bogos are 1/4, other apps are also considerably slower, but not that bad.
I'm gonna investigate further.
I added a calibrate_delay() right after the time_init() in kernel/main.c, to see if the slowdown happened before. It does!
Regards, -- Kurt Garloff, Dortmund <K.Garloff@ping.de> PGP key on http://student.physik.uni-dortmund.de/homepages/garloff
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu
| |