Subject: Re: Alpha MP goes multi-user, code committed to NetBSD-current
To: None <>
From: Toru Nishimura <>
List: port-alpha
Date: 04/22/2001 14:14:02
> Folks, today I got multiprocessor Alpha kernels to go multi-user,
> running both user and kernel code on multiple processors.  It even
> seems to be pretty stable (did a kernel build, doing a full userland
> build right now, and will build an Alpha binary snapshot with the
> MP kernel later).

It's G-R-E-A-T.  While waiting for cvs update completed for my own
copy, I would ask a small/quick question.

> There's definitely more work to do.  In particular, TLB invalidation
> traffic has to be managed better.  Take a look at the frequence of
> interprocessor interrupts:
> frau-farbissina:thorpej 23$ vmstat -i 
> interrupt                           total     rate
>   ...
> cpu0 clock                        3063914     1204
>   ...
> cpu0 shootdown ipi                3126178     1228
>   ...
> cpu1 clock                        3049191     1198
>   ...
> cpu1 shootdown ipi                2295031      902
>   ...
> Note that TLB shootdown requests are about as frequent as the clock
> interrupt :-/  Anyway, future work -- at least it runs :-)

How can this phenomenon happen?  It's counter-intuitive, and rather
magic the kernel is useful after all.

And about pmap_emulate_reference().  It's also a trouble source for my
MIPS pmap so far.   It seems necessary to pay more thought and work for
all possible cases around it.

Tohru Nishimura
Information Technology Centre
Nara Institute of Science and Technology