Kbase 16362: Slow performance on NT vs Win95 using Progress 16-bit client
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
5/10/1998 |
|
Slow performance on NT vs Win95 using Progress 16-bit client
Customers running the 16-bit Progress client product on Windows NT
may report slow performance, as compared to running on Win95,
Windows 3.1 or Windows for Workgroups. This is expected behavior, and
is due to the differences in architecture between the operating
systems.
When a 16-bit application starts in Windows 3.1/Win95/WFW, it is
running in a native mode, hence, using 16-bit operating code.
However, the NT Operating System is a true 32-bit architecture and
relies on a subsystem to run DOS and 16-bit applications.
In NT, when a 16-bit application is started, the application is
running in what NT calls a 'virtual DOS machine' (VDM). A VDM is a
virtual process that simulates the DOS environment for any DOS or
16-bit application running in it. Any services requested by the
applications are brokered by the VDM to virtual device drivers
and other service providers, which pass requests on to the real NT
drivers or other systems in NT. The standard VDM is insufficient to
support 16-bit applications, as these applications rely on services
provided by the Windows system. NT uses a system known as WOW (Win16
on Win32) to handle integration between the 16-bit application and
services provided by the 32-bit API (Application Programming
Interface). These additional layers result in slow performance when
executing 16-bit code.
NOTE: All 16-bit applications are run in the same VDM (shared memory
space), unless specified otherwise. To run a 16-bit
application in its own memory space, check the 'Run in
Separate Memory Space' box in the application's program item.
Progress Software Technical Support Note # 16362