Date: Wed, 13 Jun 2001 10:34:44 -0700 (PDT) From: John Baldwin <jhb@FreeBSD.org> To: Doug Rabson <dfr@nlsystems.com> Cc: Andrew Gallatin <gallatin@cs.duke.edu>, wilko@FreeBSD.org, freebsd-alpha@FreeBSD.org, Matthew Jacob <mjacob@feral.com> Subject: Re: followup on 8 way SMP pani Message-ID: <XFMail.010613103444.jhb@FreeBSD.org> In-Reply-To: <Pine.BSF.4.33.0106131809030.24151-100000@herring.nlsystems.com>
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On 13-Jun-01 Doug Rabson wrote:
> On Wed, 13 Jun 2001, John Baldwin wrote:
>
>>
>> On 13-Jun-01 Matthew Jacob wrote:
>> >
>> >
>> > What I needed to fix for turbolaser is to clear the timer interrupt for
>> > all
>> > CPUs but the primary CPU- this is the TLINTRMASK{0,1} registers. But,
>> > stupid
>> > me, I upgraded my source first.
>>
>> Ok, then we will need to change how platform.clockintr works slightly. (It
>> will need to do more) and then forward_*clock in sys/i386/i386/mp_machdep.c
>> will need to be moved to sys/kern/subr_smp.c, and a few tweaks need to made
>> to
>> smp_handle_ipis() in alpha/alpha/mp_machdep.c, and the tlsb will need a
>> custom
>> platform.clockintr that handles clock interrupts the way x86 does by IPI'ing
>> all other processses to go handle clock interrupts. Hmmm. Actually.
>>
>> You shouldn't even have to do this. SMP doesn't need the i8254 timecounter
>> on
>> the alpha actually, because we make it so that only the boot CPU actually
>> messes with the timecounters, so a non-i8254 timecounter should work fine on
>> SMP systems just fine right now. The reason I think dfr used hte i8254
>> before
>> was that in pre-SMPng we did need to handle clock interrupts on whatever CPU
>> owned the kernel lock, but now we don't have that same restriction.
>
> Are you saying that no code in the kernel calls nanotime(9) unless its
> running on the boot cpu? If so, then we can use the alpha timecounter. If
> not, then we need to find a decent clock somewhere in the tlaser hardware.
> I'd loke to do the same for rawhide too since the i8254 really sucks.
Argh. I forgot about that. I was thinking about clock interrupt issues.
Turning off clock interrupts for slave CPU's won't fix that. :(
--
John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
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