Controlling workload of a computer system through only external monitoring

A system for workload control comprising:

• an external observation monitor to keep track of concurrent requests and response time of said requests as said requests enter a computer system, and to keep track of corresponding responses to said requests as said responses leave the computer system;
• a model parameter estimator to use historical observations from said external observation monitor to evaluate two unknown parameters of said black box queuing model, said two unknown parameters being:
• a service time of said requests on a virtual bottleneck resource, and a service time of said requests on other resources,
• a flow optimizer to analyze said black box queuing model using said evaluated two parameters and computes concurrency limit that achieves a desirable utilization of said virtual bottleneck resource, and
• a flow controller to use said computed concurrency limit as a control parameter to limit a number of outstanding requests to said computer system.

A method for concurrency control, comprising preventing overload of resources within a computer system, the step of preventing comprising the steps of:

• collecting average response time data and concurrency data of requests in a common traffic class, of said computer system;
• using said average response time data and said concurrency data for evaluating two parameters of a model of said computer system, said two parameters being:
• a service time of said requests on a virtual bottleneck resource, and a service time of said requests on other resources;
• using said evaluated two parameters for analyzing said model for determining a target concurrency of said requests on said computer system which drives a utilization of a bottleneck resource on said computer system to a prespecified value;
• and
• employing said target concurrency for limiting admission of additional requests to said computer system.

A method for flow control, comprising preventing overload of resources within a computer system, the step of preventing including the steps of:

• collecting average response time data and concurrency data of requests in a common traffic class, of said computer system;
• using said average response time data and concurrency data for evaluating two parameters of a model of said computer system, said two parameters being:
• a service time of said requests on a virtual bottleneck resource, and a service time of said requests on other resources;
• using said evaluated two parameters for analyzing said model for determining a target flow rate of said requests on said computer system which drives a utilization of a bottleneck resource on said computer system to a prespecified value;
• and
• employing said target flow rate for limiting flow of said requests to said computer system.

A system for concurrency control, comprising means for preventing overload of resources within a computer system, the means for preventing comprising:

• means for collecting average response time data and concurrency data of requests in a common traffic class, of said computer system;
• means for employing said average response time data and said concurrency data for evaluating two parameters of a model of said computer system, said two parameters being:
• a service time of said requests on a virtual bottleneck resource, and a service time of said requests on other resources;
• means for analyzing said model for determining a target concurrency of said requests on said computer system to drive a utilization of a bottleneck resource on said computer system to a prespecified value;
• and
• means for employing said target concurrency for limiting admission of additional requests to said computer system.

A system for flow control, comprising means for preventing overload of resources within a computer system, the means for preventing comprising:

• means for collecting average response time data and concurrency data of requests in a common traffic class, of said computer system;
• means for employing said average response time data and concurrency data for evaluating two parameters of a model of said computer system, said two parameters being:
• a service time of said requests on a virtual bottleneck resource, and a service time of said requests on other resources;
• means for analyzing said model for determining a target flow rate of said requests on said computer system which drives a utilization of a bottleneck resource on said computer system to a desirable prespecified value;
• and
• means for employing said target flow rate for limiting the flow of said requests to said computer system.