[Info-vax] Command to show process rms file opens?

[Terry Kennedy]

On Thursday, July 30, 2020 at 12:00:29 PM UTC-4, Bob Gezelter wrote:
> I would suggest starting with MONITOR (or run T4 which runs MONITOR to gather data) to see what the bottleneck is.
> 
> There are many performance knobs that be adjusted, but the operative question is: What is the bottleneck?
> 
> It could be I/O. It could be paging? It could (less likely) be CPU saturation? WADR, do not speculate. Measure utilization and make the required adjustments.

I seem to recall a DEC product named something like "Performance Data Collector" that added profiling to apps at a much more fine-grained level than what you get from MONITOR or WATCH. However, I don't know if it made the transition from VAX to Alpha or IA64. It may have required the application be built with profiling support, which would make it useless if you are trying to profile system compilers/utilities. Also, I think it was one of the first products in the Great Selloff and I don't know where it ended up or if is still available. 

Some performance problems are just VMSisms. As an example, Digital Canada contracted me to write a MOP server for RSTS/E. I wrote it entirely in BP2 except for a tiny Macro-11 part to handle the few things not available in BP2, like enabling Ethernet multicast groups. It turned out to be faster on an 11/23 than on some high-end VAX like an 8800, so they asked me to add a configurable delay before the RSTS/E system would respond, to give the VAX a chance. https://www.glaver.org/ftp/tmk-software/mop-server

I also used to evaluate preproduction hardware for 3rd parties. One such product was an early 256MB SSD, built out of DRAM memory boards with a hard drive to handle nonvolatile save/restore. Even connected directly to the 8650's backplane, it didn't provide a lot of performance improvement, even fordisk-intensiveworkloads. Running 4BSD on the same or lesser model VAX often provided a 3x or more speedup, even without the SSD. But of course you give up all of the nice VMS features. This was all on VAX era hardware and may not be relevant any more, but as an anecdote when Itanium systems came out I compared performance of the admittedly low-end RX2620 VMS to some PCs I got from a dumpster dive running FreeBSD and the PCs outperformed the Itanium by a huge amount, while using a fraction of the power. Based on that, I recommended that applications that used a bunch of VMS-specific features should remain on VMS, but everything else should be moved to commodity hardware/OS.

It will be interesting to compare the future production ready release of VSI's x86 port, using optimized versions of compilers, with FreeBSD or Linux on the same hardware. Since they will all be using the LLVM backend, this should provide the most detailed "apple's to apples" performance comparison to date.