Examining and Tuning Disk Performance
By default, Task Manager continuously measures data for process I/O operations that you can select and display on the Processes tab in Task Manager. In a multiprocessor environment, this data is shared by the processors on which the process runs. When a process that generates considerable disk and network I/O, such as a database service, runs on several processors, updating the shared measurements of process I/O and global I/O operations can slow the system. You can improve the performance of I/O-intensive operations on SMP systems if you configure the system to bypass the global I/O counters and Task Manager process I/O counters. To do so, add the CountOperations entry to the registry as a REG_DWORD in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\I/O System. (If the I/O System subkey is not present, add it before creating the entry.) Set the entry value to 0. When so configured, Task Manager no longer provides per-process I/O measurements. For more information about Task Manager, see Overview of Performance Monitoring in this book.