Re: architectural goals, Byte Addressability And Beyond

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)