Date: Mon, 3 Mar 2003 04:06:41 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: Poul-Henning Kamp <phk@phk.freebsd.dk> Cc: "M. Warner Losh" <imp@bsdimp.com>, <current@FreeBSD.ORG> Subject: Re: Any ideas why we can't even boot a i386 ? Message-ID: <20030303034332.Y30986-100000@gamplex.bde.org> In-Reply-To: <20030302001614.H26391-100000@gamplex.bde.org>
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On Sun, 2 Mar 2003, Bruce Evans wrote:
> On Fri, 28 Feb 2003, Poul-Henning Kamp wrote:
>
> > My main concern would be if the chips have the necessary "umphf"
> > to actually do a real-world job once they're done running all the
> > overhead of 5.0-R. The lack of cmpxchg8 makes the locking horribly
> > expensive.
>
> Actually, the lack of cmpxchg8 only makes locking more expensive. It's
^^^^
I.e., strictly more expensive, but not much more.
> [cycle types for Athlon1600 running 386 code]
Here are whorldstone benchmarks for an Athlon. The 386 version was a
whole 0.3% slower for real time (3.2% slower for system time).
To get the system to run I had to unbreak panicifcpuunsupported() so
that it doesn't gratuitously reject Athlons (CPUs that are upward
compatible should not be rejected), and had to replace pmap.o by the
non-386 version since the 386 version caused strange errors. It's not
clear why the 386 version doesn't work -- the only internal difference
in pmap.c is that the 386 version uses invltlb() and other versions
use invlpg(). Using invlpg() would probably make things more than
0.3% slower. Selecting the best inv*() was the main optimization that
we dropped when 386 support was made incompatible with support for later
CPUs.
world with my kernel configured for I486_CPU through I686_CPU
%%%
1532 MHz AthlonXP 1600 256MB 2 ATA drives
async mounted /usr/obj (src on separate drive)
--------------------------------------------------------------
>>> elf make world completed on Sun Mar 2 16:30:55 EST 2003
(started Sun Mar 2 15:53:15 EST 2003)
--------------------------------------------------------------
2260.31 real 1729.55 user 326.24 sys
40208 maximum resident set size
2248 average shared memory size
1762 average unshared data size
127 average unshared stack size
14959205 page reclaims
25630 page faults
0 swaps
43481 block input operations
3963 block output operations
0 messages sent
0 messages received
5 signals received
313523 voluntary context switches
607085 involuntary context switches
%%%
world with my kernel configured for I386_CPU except for pmap.o
%%%
1532 MHz AthlonXP 1600 256MB 2 ATA drives
async mounted /usr/obj (src on separate drive)
--------------------------------------------------------------
>>> elf make world completed on Mon Mar 3 03:00:45 EST 2003
(started Mon Mar 3 02:22:57 EST 2003)
--------------------------------------------------------------
2267.98 real 1730.21 user 336.73 sys
40208 maximum resident set size
2245 average shared memory size
1756 average unshared data size
127 average unshared stack size
14958931 page reclaims
26265 page faults
0 swaps
44148 block input operations
3898 block output operations
0 messages sent
0 messages received
6 signals received
313986 voluntary context switches
598687 involuntary context switches
%%%
Bruce
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