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From: John Levine <johnl@taugh.com>
Newsgroups: comp.arch
Subject: Re: architectural goals, Byte Addressability And Beyond
Date: Fri, 31 May 2024 19:44:49 -0000 (UTC)
Organization: Taughannock Networks
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According to John Savard  <quadibloc@servername.invalid>:
>On Thu, 30 May 2024 03:25:14 -0000 (UTC), John Levine
><johnl@taugh.com> wrote:
>
>>I do not entirely understand why IBM keeps adding special purpose
>>instructions to z. Maybe it's partly marketing, but they have a
>>largely captive audience so it has to be more than that.
>
>One possibility is to _keep_ that audience captive even after all the
>patents expire that are applicable to machines with the z/Architecture
>in its current state, if you are reluctant to believe that these new
>instructions genuinely improve performance.

Back in the last millenium there were a bunch of companies that made
clones of IBM mainframes. They all failed. It's the whole ecosystem of
hardware and software, not just individual features that keep the
customers nor patents.

I have to say I'm somewhat surprised that IBM has put a lot of effort
into running linux on zSeries, since that's about as un-captive as you
can get. I would imagine that for some kinds of heavily threaded
workloads they could be competitive since the z machines have upwards
of a hundred CPUs with a shared mostly consistent cache.

-- 
Regards,
John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly