[Info-vax] DECnet Phase IV broken after VSI update

[Bill Gunshannon]

On 11/5/21 11:39 AM, Craig A. Berry wrote:
> 
> On 11/5/21 1:46 AM, David Jones wrote:
>> On Thursday, November 4, 2021 at 8:54:37 PM UTC-4, Lawrence D’Oliveiro 
>> wrote:
>>> On Thursday, November 4, 2021 at 5:54:21 PM UTC+13, osuv... at gmail.com 
>>> wrote:
>>>> Most of PTD$ code runs in kernel mode with some at elevated IPL.
>>> So does a device driver. Why do the PTD functions have to be a 
>>> separate layer from the device driver? Particularly a separate, 
>>> caller-visible layer that breaks the normal driver QIO abstraction?
>>>> PTD$READ/WRITE queue request packets directly to FTDRIVER,
>>>> skipping some of the overhead of $QIO processing.
> 
>>> Remember, these are terminals we are talking about -- devices
>>> geared to the limits of human I/O bandwidth. Any “overheads” 
>>> associated with
>>> I/O processing would be insignificant compared to the time it takes for
>>> a human to type input or read output.
> 
>> That's a PC menatility, VAXes were timesharing systems with many
>> concurrent users. C was a second class language in the VAX/VMS world,
>> too, so the API wasn't designed to cater the patterns of the C RTL.
>> Threads didn't exist, your server process handling many PTYs was
>> state driven by ASTs delivered by the terminal driver.
> 
> And I remember lots of complaints from people who had to slow down their
> typing so the VAX could catch up.

The only time I ever saw that happen on a VAX was when I was using
EUNICE and someone else fired up the ADA Compiler.  :-)

bill