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Date:      Sun, 2 Feb 1997 16:44:36 -0500
From:      "David S. Miller" <davem@jenolan.rutgers.edu>
To:        terry@lambert.org
Cc:        terry@lambert.org, michaelh@cet.co.jp, netdev@roxanne.nuclecu.unam.mx, roque@di.fc.ul.pt, freebsd-smp@freebsd.org, smpdev@roxanne.nuclecu.unam.mx
Subject:   Re: SMP
Message-ID:  <199702022144.QAA19640@jenolan.caipgeneral>
In-Reply-To: <199702022135.OAA08696@phaeton.artisoft.com> (message from Terry Lambert on Sun, 2 Feb 1997 14:35:27 -0700 (MST))

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   From: Terry Lambert <terry@lambert.org>
   Date: Sun, 2 Feb 1997 14:35:27 -0700 (MST)

   Well, Sun generally does things right.  I was more concerned with a
   number of Intel motherboards where we are seeing APIC_IO problems.
   They seem to fail this case.

Oh god, the APIC, programming that thing is like pulling out ones
fingernails with a crowbar.  They dropped those fabs on the floor big
time.

Intel should have sub contracted someone who knew what they were doing
for that chipset.

So outside of the APIC_IO cases, all else is smoothe and passes the
test cases right?

I mean Jesus Christ, how do you implement a read/writer lock for
crying out loud with that problem?  If I understand the issue
properly, this means you'd have to lock the entire bus for every
_access_ to any piece of the lock structure.  I'm glad my primary
platform isn't the Intel, but it actually a fun chip to optimize
assembly for.

(Note, Sun isn't the only one who got it right.  SGI, HP, DEC, and
 just about every other hardware manufacturer whose hardware cache
 coherency implementation I am intimately familiar with does it right.
 Intel is the only fuckup case I've run into, and I had not idea it
 was so bad until you pointed out the problem just now.)

---------------------------------------------////
Yow! 11.26 MB/s remote host TCP bandwidth & ////
199 usec remote TCP latency over 100Mb/s   ////
ethernet.  Beat that!                     ////
-----------------------------------------////__________  o
David S. Miller, davem@caip.rutgers.edu /_____________/ / // /_/ ><



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