Andrey (andrey.semashev.delete@this.gmail.com) on April 10, 2021 10:36 am wrote:
> Robert Williams (crispysilicon.delete@this.gmail.com) on April 10, 2021 8:24 am wrote:
> > Mark Roulo (nothanks.delete@this.xxx.com) on April 9, 2021 12:54 pm wrote:
> > > My employer runs a lot of hand optimized numeric code. We started with AltiVec
> > > on PowerPC, then moved to SSE on x86 and are now using AVX2 on x86.
> > >
> > > One reason we HAVE NOT moved to Avx-512 is that the developers like being able to run code on their
> > > desktop/laptop machines. Until recently, Avx-512 was pretty much only available on server parts.
> > >
> > > Making it difficult (or impossible) to run code on developer
> > > machines discourages adoption of new capabilities.
> > >
> > > Note that a SLOW Avx-512 implementation on the laptop/desktop chips would have
> > > been okay. The developers (other than the performance optimization) team don't
> > > need the code to run QUICKLY on their machines -- they just need it to run.
> >
> > I get you, but it's not the same.
> >
> > In the case of AVX-512, it's going to see some use for average Joe. This isn't about development.
> > This is about the point that for TSX to be fast enough to be worth using, it's going to require
> > complexity that is going to be counterproductive to desktop/mobile. It's going to sit cold.
>
> Counterproductive in what sense? Provided that TSX does provide performance benefits
> and universally available, I don't see why it would be unused in the software.
>

May be, because benefits are unlikely to be seen on CPU with 2 to 8 cores?

> Also note that transistor budget grows with each node, so what is
> presumed to be too complex/expensive today might not be tomorrow.
>

There are cheap transistors, far away from inner core, and expensive transistors close to it.
My impression is that TSX occupies transistors in one of the most expensive areas, near load and store queues.
But I am not a CPU architect.