Hybrid and predictive admission control strategies for a server

• US 6,823,392 B2
• Filed: 11/29/2001
• Issued: 11/23/2004
• Est. Priority Date: 11/16/1998
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Cherkasova, Ludmila, Phaal, Peter
• Primary Examiner(s): Dinh, Dung C.
• Assistant Examiner(s): EDELMAN, BRADLEY E
• Application Number:
  US09/995,760
• Publication Number:
  US 20020052962A1
• Time in Patent Office: 1,090 Days
• Field of Search: 709/226, 709/225, 709/229, 370/230
• US Class Current: 709/229
• CPC Class Codes: H04L 41/5019 Ensuring fulfilment of SLA
• CPC Class Codes: H04L 47/745 Reaction in network
• CPC Class Codes: H04L 47/788 Autonomous allocation of resources
• CPC Class Codes: H04L 47/822 Collecting or measuring resource availability data
• CPC Class Codes: H04L 67/01 Protocols
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• CPC Class Codes: H04L 67/56 Provisioning of proxy services store-and-forward switching systems in data switching networks H04L12/54

Abstract

An admission control system for a server including an admission controller that receives a stream of messages from one or more clients targeted for the server. The admission controller relays to the server the messages in the stream that correspond to a number of sessions already underway between the clients and the server. The admission controller also relays to the server the messages in the stream that do not correspond to sessions already underway if a hybrid and predictive admission control strategy using information provided by a resource monitor indicates that additional sessions can be handled by the server. The admission controller defers the messages otherwise.

Claims

1. An admission control system for a server, comprising:

a resource monitor configured to determine a server utilization metric for at least one resource of a set of resources for said server and said resource monitor is also configured to measure a number of refused connections and a number of aborted requests; and

an admission controller configured to admit a session to said server based on a function of an admission control factor and the server utilization metric determined by said resource monitor, wherein said admission control factor is increased by a predetermined amount in response to a total of said number of refused connections and said number of aborted requests being greater than zero.

2. The admission control system according to claim 1, wherein said admission control factor is configured to cover a range from responsive to stable.

3. The admission control system according to claim 1, wherein a default value of said admission control factor is set to a highest value.

4. The admission control system according to claim 1, wherein said admission control factor, when at a lowest value, is unchanged in response to a total of said number of refused connections and said number of aborted requests being equal to zero.

5. The admission control system according to claim 1, wherein said admission control factor is reduced by a predetermined amount in response to a total of said number of refused connections and said number of abort requests being equal to zero.

6. The admission control system according to claim 1, wherein said admission control factor is a variable having a lowest value and a highest value.

7. The admission control system according to claim 1, wherein said resource monitor measures said server utilization metric over a time interval.

8. The admission control system according to claim 7, wherein said function is utilized to determine an observed server utilization based on said admission control factor and said server utilization metric.

9. The admission control system according to claim 8, wherein said admission control system rejects new sessions in response to said observed server utilization being greater than a server utilization threshold.

10. The admission control system according to claim 8, wherein said admission control system accepts new sessions in response to said observer server utilization being less than or equal to a server utilization threshold.

11. A method of admission control for a session in a server, said method comprising:

determining an admission control factor for a time interval based on a total number of refused connections and aborted requests measured during a previous time interval;

determining a server utilization for said time interval;

determining an observed server utilization based on said admission control factor and said server utilization; and

admitting said session for a next time interval in response to said observed server utilization being less than a server utilization threshold.

12. The method according to claim 11, further comprising:

denying said session for a next time interval in response to said observed server utilization being greater than or equal to said server utilization threshold.

13. The method of claim 11, wherein determining an admission control factor for a time interval based on a total number of refused connections and aborted requests measured during a previous time interval further comprises:

determining whether the admission control factor is set to a lowest value in the previous time interval;

determining whether the total number of refused connections and aborted requests is equal to zero in the previous time interval; and

maintaining the admission control factor from the previous time interval for the time interval in response to the admission control factor being set to the lowest value in the previous time interval and the total number of refused connections and aborted requests being equal to zero.

14. The method of claim 11, wherein determining an admission control factor for a time interval based on a total number of refused connections and aborted requests measured during a previous time interval further comprises:

determining whether the total number of refused connections and aborted requests is equal to zero in the previous time interval; and

reducing the admission control factor for the time interval by a predetermined amount in response to the total number of refused connections and aborted requests being equal to zero in the previous time interval.

15. The method of claim 11, wherein determining an admission control factor for a time interval based on a total number of refused connections and aborted requests measured during a previous time interval further comprises:

determining whether the total number of refused connections and aborted requests is greater than zero in the previous time interval; and

increasing the admission control factor for the time interval by a predetermined amount in response to the total number of refused connections and aborted requests being greater than zero in the previous time interval.

16. A method for controlling admission of a session to a computing system, the method comprising:

measuring a server utilization for a plurality of time intervals T(1) . . . T(n);

calculating an admission control factor for the time interval T(n) based on at least one metric measured during the time interval T(n−

1);

calculating a predicted server utilization based on one or more of the measured server utilizations measured for the time intervals T(1) . . . T(n), wherein the calculated admission control factor is used to determine which of the measured server utilizations are used to calculate the predicted server utilization; and

comparing the predicted server utilization to a threshold to determine whether to admit a new session.

17. The method of claim 16, wherein calculating a predicted server utilization based on one or more of the measured server utilizations measured for the time intervals T(1) . . . T(n) further comprises calculating the predicted server utilization based at least on a most recent measured server utilization, the most recent measured utilization being associated with the time interval T(n).

18. The method of claim 17, wherein calculating a predicted server utilization based on one or more of the measured server utilizations measured for the time intervals T(1) . . . T(n) further comprises calculating the predicted server utilization based on the most recent measured server utilization and at least one other measured server utilization being associated with the time intervals T(1) . . . T(n−

1) if the calculated admission control factor is less than a previously calculated admission control factor.

19. The method of claim 16, wherein calculating an admission control factor for the time interval T(n) based on at least one metric measured during the time interval T(n−

1) further comprises calculating the admission control factor for the time interval T(n) based on at least one of a measured number of refused connections and a measured number of aborted requests measured during the time interval T(n−

1).

20. An apparatus comprising:

means for determining an admission control factor for a time interval based on a total number of refused connections and aborted requests measured during a previous time interval;

means for determining a server utilization for said time interval;

means for determining an observed server utilization based on said admission control factor, and said server utilization; and

means for admitting said session for a next time interval in response to said observed server utilization being less than a server utilization threshold.