[Info-vax] VMS x86 performance ?

[Craig A. Berry]

On 10/30/20 3:43 PM, IanD wrote:
> On Saturday, October 31, 2020 at 12:19:06 AM UTC+11, Michael Moroney wrote:
>>
>> Still too early to tell.  The compilers have optimization off and frankly, the
>> generated code is hideous.
>>
>> Despite that, boots are wicked fast.

> Fair enough in one aspect but I wasn't interested in how optimised or
> not things are but more interested in a ballpark approximate
> indication of how things look so far

Why would you think that how fast non-optimized code runs would give you
a meaningful ballpark figure? And it's not just the code generation that
would not be optimized at this point. They probably have debug
statements all over the place that will eventually be removed or
compiled out.  If I remember right from the Itanium port, things like
stack unwinding during an exception and alignment faults all over the
place were quite a mess in the initial builds and took quite a few
iterations to get into decent shape.

The particular rough edges on x86 may be different, but there will be
some, and some of them will have a performance impact. It doesn't make
much sense to spend resources on making things crash faster.  After the
the native compilers have gone through a few iterations and
architecture-specific parts of the kernel have gotten to the point where
they aren't hanging or blowing up too often, then of course everyone
will want to know how fast it runs.  But at the moment it's not so much
comparing apples and oranges as meat and vegetables.

> The fact that it boots wickedly fast is also an indication is it
> not?

It's good news, but it may not mean what you think it means.  I believe
they have done a lot of work on the boot path, so it's not necessarily
the same code that is running on other architectures.