Re: Arguments for a sane ISA 6-years later

On 7/26/2024 10:00 AM, Anton Ertl wrote:

"Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> writes:

On 7/25/2024 1:09 PM, BGB wrote:

At least with a weak model, software knows that if it doesn't go through
the rituals, the memory will be stale.

 There is no guarantee of staleness, only a lack of stronger ordering
guarantees.
 

The weak model is ideal for me. I know how to program for it

 And the fact that this model is so hard to use that few others know
how to program for it make it ideal for you.
 

and it's more efficient

 That depends on the hardware.
 Yes, the Alpha 21164 with its imprecise exceptions was "more
efficient" than other hardware for a while, then the Pentium Pro came
along and gave us precise exceptions and more efficiency.  And
eventually the Alpha people learned the trick, too, and 21264 provided
precise exceptions (although they did not admit this) and more
efficieny.

[...]
Iirc, the Alpha requires a memory barrier even for RCU because, iirc, it does not honor data dependent loads... These are a no-op on most archs, but Alpha, well, nope!