[Info-vax] What would be involved in moving RMS into kernel mode ?

[Dave Froble]

On 5/6/2023 10:43 AM, Arne Vajhøj wrote:
> On 5/6/2023 6:39 AM, Jan-Erik Söderholm wrote:
>> About RMS Global Buffers. What files are these usually used for?
>> I have got an (maybe wrong) impression that it is mostly indexed
>> files "databases".
>>
>> As an example, Rdb is not using RMS for the data/storage. It is
>> used for some Rdb files like the backup files and "export" files,
>> but for that I do not see can gain much from faster global buffers...
>
> I am far from an expert in RMS (unlike Hein), but my very basic
> understanding is that global buffers work for both sequential
> and index-sequential files.

I believe that is true.

> But to provide value in the form of better performance then:
> - the same file need to be accessed by multiple processes
> - the access need to go through RMS

Yes.

> Which may have been a common scenario 35 years ago, but
> not so much today.

It's still very common today.

However, global buffers are no longer very helpful.  Why?  Because of the 
caching added to VMS somewhere around V7 or V8.

The CODIS application has one file that just about every process has open.  One 
would consider such a scenario to benefit from global buffering.  However, DAS 
(the database product) didn't offer global buffers.  When most of your data is 
in cache, things can get rather fast.  What was observed was performance quite 
fast with caching, and a real slog without.

> An indexed-sequential file being updated by multiple
> processes running some Cobol/Basic/Pascal application
> designed 35 years ago is probably the most likely
> combo to match those criteria.

And caching has satisfied that need.

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David Froble                       Tel: 724-529-0450
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