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From: "Stephen Fuld" <SFuld@alumni.cmu.edu.invalid>
Newsgroups: comp.arch
Subject: Re: architectural goals, Byte Addressability And Beyond
Date: Fri, 7 Jun 2024 03:13:54 -0000 (UTC)
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Lawrence D'Oliveiro wrote:

> On Thu, 6 Jun 2024 11:55:22 -0000 (UTC), John Levine wrote:
> 
> > If you're doing something that is mostly read-only and easy to
> > parallelize, then it makes sense to use a farm of cheap PCs. But if
> > you are a bank or an airline, you need to be able to lock your
> > database so that you debit a bank account or sell a plane seat
> > exactly once.  There is a rule of thumb that the cost of locking
> > something grows roughly as the square of the number of things
> > contending for the lock.
> 
> Remember that the number of users actually buying a product at any
> given time is only a small proportion (say 1%) of the number of users
> currently accessing the site.

I don't know where you got that number, but even if it is true for a
retail storefront type site, I am pretty sure it isn't true for a bank
(what John was talking about, and a substantial part of mainframes's
user base).  Few people "browse" bank's the products.  :-)  Even for an
airline (the other example John gave.) I suspect that far more than 1%
of the accesses are updates.



-- 
 - Stephen Fuld 
(e-mail address disguised to prevent spam)