Trace Environment

Four groups:

1. INS. Instructional workload. HP-UX.

2. RES. Research workload. HP-UX.

3. WEB. Web server. HP-UX.

4. NT. Variety of uses. Windows-NT.

On HP-UX used auditing system with small kernel changes to record current working directory.

On Windows NT used own tracer tool to collect system activity through a file system filter driver. Trace driver just recorded activity and then passed on to real file system.

Also had to implement fast-dispatch function for when operating system tries to optimize requests. Also problems with intercepting memory-mapped operations.

Two problems with resulting NT traces:

1. Traces at file system level rather than system call level---not the same view. For example multiple calls on a cache miss or read ahead.

2. NT and Unix file system interfact different---not stat() call in NT. Mapped these calls to closest Unix equivalent.