O'Reilly logo

Guru's Guide to SQL Server Architecture and Internals, The by Ken Henderson

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Recap

In order to increase scalability and support Windows fibers, SQL Server has managed its own scheduling since version 7.0 via UMS. UMS serves as a thin layer between the server and the operating system that provides much of the same functionality offered by the Win32 thread and scheduling primitives, but it does so without requiring as many transitions into kernel mode or as many context switches.

A key difference between UMS and Windows' scheduler is that UMS is a cooperative scheduler. It relies on workers to voluntarily yield often enough to keep the system running smoothly. By putting control of when a thread is scheduled under the direction of the server, a much greater responsibility is placed on SQL Server developers to write code ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required