Abstract: A method and system for monitoring execution performance of a program is provided. Profiling functionality may be qualified by setting various qualifying flags at the request of a user. These qualifying flags may be used to limit the amount of trace data being generated or processed, thereby providing a more focused picture of an application's execution to the user. One or more trace,qualifying conditions are selectable by a user and are used during a profiling phase of application execution or during a post-processing phase of analyzing the application execution. During a profiling phase, an occurrence of a selected event or a timer interrupt is detected, and a determination is made as to whether a trace qualifying condition has been previously selected. In response to a determination that a trace qualifying condition has been selected, a trace record is then generated.

Abstract: A method, system, and computer program product is presented for minimizing overhead that may be incurred by executing specialized code, such as debug code or instrumentation code for monitoring the performance of the application, that is present within an application. The application executes on a data processing system having a processor containing predicate registers. The application is compiled in a manner in which the processor instructions for the specialized code are predicated using a set of one or more predicate registers that are dedicated or reserved by software convention for predicating the specialized code. In other words, for a given application, compilers and other sources of machine instructions do not generate any predicated processor instructions, other than processor instructions for the specialized code, which use the reserved predicate registers. When the application executes, neither the operating system nor other applications use the reserved predicate registers.

Abstract: A method and apparatus is presented for controlling spin lock instrumentation for a spin lock in a system with a cache. A lock flag represents a busy state for the spin lock; a first instrumentation flag is a global variable representing an enablement state for the spin lock instrumentation. A second instrumentation flag, stored within the same cache line as the lock flag, is also maintained as an updateable indication of the first instrumentation flag. Prior to each acquirement of the spin lock, the second instrumentation flag is checked for an indication that spin lock instrumentation is enabled. Although a reading of the lock flag may generate a cache miss, the lock flag is necessarily checked upon attempting to acquire the lock; the check of the second instrumentation flag cannot generate a superfluous cache miss because the second instrumentation flag is in the same cache line as the lock flag.

Abstract: A method of determining Internet delays associated with requests from a Web client connectable to a Web server. The method begins at the Web server in response to a first HTTP request. In particular, the Web server serves a response to the first HTTP request and logs a server processing time associated with serving that response. After the response is delivered back to the Web client that initiated the request, an end user response time associated with the first HTTP request is calculated at the Web client. Upon a new HTTP request (typically the next one), the end user response time associated with the first HTTP request is then passed from the Web client to the Web server in a cookie. The Internet delay associated with the first HTTP request is then calculated by subtracting the server processing time from the end user response time.

Abstract: A method and system is presented for controlling spin lock instrumentation for a spin lock in a data processing system that has a cache. A lock flag represents a busy state for the spin lock; a first instrumentation flag is a global variable that represents an enablement state for the spin lock instrumentation. A second instrumentation flag, stored within the same cache line as the lock flag, is also maintained as an updateable indication of the first instrumentation flag. Prior to each acquirement of the spin lock, the second instrumentation flag is checked to see if it indicates that spin lock instrumentation is enabled. Although a reading of the lock flag may generate a cache miss, the lock flag is necessarily checked upon attempting to acquire the lock; the check of the second instrumentation flag cannot generate a superfluous cache miss because the second instrumentation flag is in the same cache line as the lock flag.

Abstract: A monitor located between a Web browser and a server upon which a server application is running. The monitor is useful for recording a set of URLs (sometimes referred to as a “request list”) that issue from the Web browser during a sample interactive session between the user of the client machine and the server application. The URL request list trace or session “workload” may then be used to benchmark the server application by supplying the information as an input to a set of HTTP submitter routines. Each HTTP submitter routine simulates a particular user of a client machine connected to the server application. Each routine then “replays” the interactive session recorded by the monitor so that the overall performance of the server application against “multiple” simulated users may be evaluated.

Abstract: A method of logging information in a computer network having a Web client connectable to a Web server. In response to the HTTP request (and as a result of receiving a response to that request), a response time associated with that first HTTP request is calculated. Thereafter, the response time calculated is passed from the Web client on a subsequent HTTP request to that Web server, where the information is logged for later use. In a preferred embodiment, the response time associated with the first HTTP request is passed in a cookie of the second HTTP request.