Try this:
http://www.microsoft.com/hwdev/desinit/csa1.htm
Little snip from that link:
<i>
How Does WDM Streaming Achieve Low Latency?
WDM Streaming is accomplished by a set of kernel-mode drivers that pass data streams to each other using a specific transport (for example, shared memory areas). Kernel-mode drivers calling each other and using shared memory areas contribute to lower latency in several ways:
No time-consuming kernel-mode/non-kernel-mode transitions and parameter validations are necessary to render a data stream.
No extra copies of the data stream are necessary.
Kernel-mode drivers can access the hardware directly through calls to the WDM base services.
Less context switching is done.
Fewer IRPs might be generated.
Parameters need not be probed, and the security layer is bypassed.
Streaming data in kernel mode also contributes to synchronization because kernel-mode drivers have access to operating-system kernel scheduling services, which have relatively predictable response times.
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<font size=-1>[ This Message was edited by: subhuman on 2001-11-01 11:00 ]</font>