> > MS SQL have the similar approach and very happy with it.
> > Google for 'user mode scheduler'
> >
> >
> MS SQL derived from Sybase SQL Server which was designed around a
> proprietary Sybase thread system. It isn't the least bit surprising
> that it performs better with a voluntary scheduler than a general
> purpose one, but I wouldn't generalize on this at all.

UMS was introduced in MS SQL 2000 which is very far from Sybase
SQL Server. MS SQL 2000 and MS SQL 4.2 (where MS take Sybase
SQL Server, iirc) are completely different products

> There is a trade-off with internal synchronization and mutexes versus
> parallelism and read/write locks that Sybase and Microsoft took differently
> than I did with Vulcan.

I know how you did it with Vulcan but i can't know the same level of details
about MS SQL :)

> If you take MS SQL Server's scheduler out of context,
> you are likely to come to incorrect conclusions. A database system
> design has to be studied as a system, not as a system of interchangeable
> parts.

My point is that user mode scheduler is not an evil by definition. I just
point to the one of successful implementation of it.

Regards,
Vlad