[Info-vax] What does VMS get used for, these days?

[Arne Vajhøj]

On 11/15/2022 1:36 PM, Simon Clubley wrote:
> On 2022-11-15, Jan-Erik Söderholm <jan-erik.soderholm at telia.com> wrote:
>> Den 2022-11-15 kl. 15:11, skrev Simon Clubley:
>>> On 2022-11-14, Arne Vajhøj <arne at vajhoej.dk> wrote:
>>>> On 11/14/2022 1:59 PM, Simon Clubley wrote:
>>>>> On 2022-11-11, Arne Vajhøj <arne at vajhoej.dk> wrote:
>>>>>> On 11/11/2022 7:40 PM, Scott Dorsey wrote:
>>>>>>> =?UTF-8?Q?Arne_Vajh=c3=b8j?=  <arne at vajhoej.dk> wrote:
>>>>>>>> On 11/10/2022 9:51 AM, Scott Dorsey wrote:
>>>>>>>>> As software becomes more and more expensive, I think the need to have an
>>>>>>>>> efficient operating system that provides database features in the kernel
>>>>>>>>> becomes more important.
>>>>>>>>
>>>>>>>> Database in the actual OS kernel or just database shipping with the
>>>>>>>> OS distribution?
>>>>>>>>
>>>>>>>> It is not uncommon to put application functionality in the
>>>>>>>> kernel today, but I am not keen on the idea.
>>>>>>>
>>>>>>> I think in the kernel.  Maybe not in the top ring, but in a ring below it.
>>>>>>> I want fast database access, I want rapid transaction turnover, I don't care
>>>>>>> necessarily about realtime operation or any direct UI other than for
>>>>>>> administration, or ever specifically making deadline.  I'm thinking of a
>>>>>>> specialized database engine.
>>>>>>
>>>>>> I don't think I have ever heard about that for database.
>>>>>
>>>>> Rdb ? :-)
>>>>
>>>> I thought that was in user space not kernel space (P0 vs S0 in
>>>> more VMSish teminology).
>>>
>>> I thought the core Rdb components ran in Executive mode. Was I wrong
>>> about that ?
>>
>> Maybe so, but the question was if Rdb run in the kernel, wasn't it?
> 
> If you read Scott's requirements above, you will see he was talking about
> it being part of the kernel, but running at a ring below kernel mode.
> That description fits executive mode perfectly.

It certainly matches the running in inner mode part.

It does not really match the concept as such.

The point of Tux, http.sys etc. is to avoid switches
between user and kernel mode and to avoid copying
data between process buffers and system buffers.

Rdb does not achieve any of that.

Rdb must be running in executive mode not for
performance reasons but for safety/security reasons.
Having an intended multi-user database running embedded
in processes create some unique problems. Having the
data structures protected against user mode access
mitigate those.

Arne