THROTTLE DISK I/O USING DISK DRIVE SIMULATION MODEL

• US 20130132057A1
• Filed: 11/17/2011
• Published: 05/23/2013
• Est. Priority Date: 11/17/2011
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: ZUO, YUE, DENG, YIMIN, CHAU, HO YUEN, FOLTZ, FORREST CURTIS
• Granted Patent: US 9,395,920 B2
• Time in Patent Office: Days
• US Class Current: 703/21
• CPC Class Codes: G06F 11/3419 by assessing time
• CPC Class Codes: G06F 11/3433 for load management allocation of a server based on load conditions G06F9/505; load rebalancing G06F9/5083; redistributing the load in a network by a load balancer H04L67/1029
• CPC Class Codes: G06F 11/3447 Performance evaluation by modeling
• CPC Class Codes: G06F 11/3485 for I/O devices
• CPC Class Codes: G06F 2201/815 Virtual
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0664 at device level, e.g. emulation of a storage device or system
• CPC Class Codes: G06F 3/0676 Magnetic disk device

Abstract

Computerized methods, systems, and computer-storage media for throttling requests from virtual machines (VMs) to a hard-disk drive (HDD) are provided. When a request for disk I/O is received from a VM, a disk-drive model that simulates performance characteristics of the HDD is accessed. During access, the disk-drive model'"'"'s estimation of HDD parameters and the disk-drive model'"'"'s estimation of a current state of a disk head of the HDD are gathered. A projected execution time to carry out the request is computed as a function of the estimated HDD parameters and the estimated current state of the disk head. Also, an actual execution time to carry out the request is measured upon allowing the request to pass to the HDD. Using a comparison of the projected execution time and the actual execution time, the traffic of the requests from the VMs is throttled.

Claims

1. One or more computer-readable media having computer-executable instructions embodied thereon that, when executed, perform a method for throttling requests from one or more virtual machines (VMs) to a hard-disk drive using a filter driver, the method comprising:

receiving a subject request from a service application running on the one or more VMs;

accessing a disk-drive model that behaves substantially similar to the hard-disk drive, wherein the process of accessing comprises;

(a) reading the disk-drive model'"'"'s simulation of performance characteristics of the hard-disk drive; and

(b) reading the disk-drive model'"'"'s simulation of a current state of a disk head of the hard-disk drive;

computing a projected execution time to carry out the subject request as a function of the performance characteristics and the current state of the disk head;

measuring an actual execution time to carry out the subject request upon passing the subject request to the hard-disk drive; and

throttling traffic of the requests from the VMs to the hard-disk drive using a comparison of the projected execution time and the actual execution time.

2. The one or more computer-readable media of claim 1, wherein the method further comprises sending the subject request to a hard-disk drive for fulfillment of the subject request.

3. The one or more computer-readable media of claim 1, wherein the subject request represents a read operation or a write operation directed to a virtual hard disk (VHD) file that maintains stored data on a hard disk of the hard-disk drive, and wherein the disk head is configured to read or write to the hard disk in response to the read operation or the write operation, respectively.

4. The one or more computer-readable media of claim 3, the method further comprising building the disk-drive model, wherein the disk-drive model embodies a soft-disk representation of the hard-disk drive, which supports VHD files associated with the one or more VMs.

5. The one or more computer-readable media of claim 1, wherein computing a projected execution time to carry out the subject request comprises:

identifying a first position of the disk head when carrying out a precedent request;

extrapolating from the disk-drive model a second position of the disk head when carrying out the subject request; and

calculating a time for the disk head to travel between the first position and the second position.

6. The one or more computer-readable media of claim 1, wherein the simulated performance characteristics are specified by a set of estimated parameters that correspond to a set of actual parameters existing on the hard-disk drive.

7. The one or more computer-readable media of claim 6, wherein the set of estimated parameters comprise a latency of a controller, and wherein the controller latency includes a time consumed by the controller to interpret and execute the subject request.

8. The one or more computer-readable media of claim 6, wherein the set of estimated parameters comprise a speed at which the disk head seeks, and wherein the seek speed includes a rate at which the disk head travels across tracks on a hard disk.

9. The one or more computer-readable media of claim 6, wherein the set of estimated parameters comprise a latency of rotation, and wherein the rotational latency includes a time to rotate a hard disk to a location of data targeted by the subject request.

10. The one or more computer-readable media of claim 6, wherein the set of estimated parameters comprise a rate of data transfer, and wherein the data transfer rate includes a speed at which the disk head reads of writes data targeted by the subject request to or from a hard disk.

11. The one or more computer-readable media of claim 1, wherein throttling traffic of the requests from the VMs to the hard-disk drive using a comparison of the projected execution time and the actual execution time comprises determining an amount of time the projected execution exceeds the actual execution time.

12. The one or more computer-readable media of claim 11, the method further comprising assigning one of the VMs a performance threshold that is based on the exceeding amount of time.

13. The one or more computer-readable media of claim 11, the method further delaying in one or more queues the requests from the VMs to the hard-disk drive in proportion to a value of the performance threshold.

14. A computer system capable of throttling a rate at which requests from a service application are executed by a hard-disk drive utilizing a disk-drive model, the computer system comprising at least one physical machine configured with a computer-storage medium having a plurality of computer software components running thereon, the computer software components comprising:

a virtual machine (VM) for hosting a portion of the service application, wherein the service application issues a second request to read data from or write data to a virtual hard disk file associated with the VM;

a filter driver for comparing a projected execution time of a first request, which is calculated using the disk-drive model that simulates performance characteristics of the hard-disk drive, against an actual execution time of the first request, which is measured upon carrying out the first request at the hard-disk drive, and for affecting a time for carrying out the second request based on an outcome of the comparison.

15. The computer system of claim 14, further comprising a VM bus to deliver the request from the service application to the filter driver.

16. The computer system of claim 14, further comprising one or more queues for holding requests issued from the VM and delayed by the filter driver, wherein the one or more queues feed into the hard-disk drive.

17. The computer system of claim 14, wherein the first request represents a read or write operation that targets data on a first sector of the hard-disk drive, wherein the second request represents a read or write operation that targets data on a second sector of the hard disk, and wherein a disk head of the hard-disk drive is configured to read or write to the hard disk in response to the read or write operation.

18. The computer system of claim 17, wherein the disk-drive model considers a set of estimated parameters, which correspond to a set of actual parameters of the hard-disk drive, and a time for a disk head to travel from the first sector to the second sector of the hard disk.

19. A computerized method for limiting a rate of requests flowing to a hard-disk drive, the method comprising:

employing a disk-drive model to compute a projected execution time for the hard-disk drive to carry out a first request;

measuring an actual execution time taken by the hard-disk drive to carry out the first request;

comparing the projected execution time against the actual execution time; and

managing the rate of the requests allowed to pass to the hard-disk drive as a function of an outcome of the comparison, the process of managing comprising;

(a) when the projected execution time exceeds the actual execution time by a value greater than a performance threshold, imposing a delay upon a second request before passing the second request to the hard-disk drive, wherein the delay is imposed until the difference between the actual execution time and the projected execution time satisfies the performance threshold; and

(b) otherwise, passing the second request to the hard-disk drive upon receipt of the second request.

20. The computerized method of claim 19, wherein the hard-disk drive includes a disk head for reading data from or writing data to a hard disk, and wherein the disk-drive model considers a time for the disk head to travel from a first sector of data targeted by the first request and a second sector of data targeted by the second request.