Early event-based notification for VM swapping
Various embodiments disclosed herein are related to a non-transitory computer readable storage medium. In some embodiments, the medium includes instructions stored thereon that, when executed by a processor, cause the processor to receive, from a user-space application, a request to detect swapping activity satisfying a threshold condition, detect the swapping activity satisfying the threshold condition, and, in response to occurrence of the threshold condition, send a response that indicates that the swapping activity satisfies the threshold condition.
1. A non-transitory computer readable storage medium comprising instructions stored thereon that, when executed by a processor, cause the processor to:
receive, from a user-space application, a request to detect swapping activity satisfying a threshold condition, wherein the swapping activity comprises swapping pages of a virtual machine (VM) from a host memory to a storage location shared by multiple VMs, wherein a page table of the VM specifies physical locations of non-swapped pages in the host memory and physical locations of swapped pages in the storage location;
detect the swapping activity satisfying the threshold condition; and
in response to occurrence of the threshold condition, send a response that indicates that the swapping activity satisfies the threshold condition.
2. The medium of claim 1 , further comprising instructions stored thereon that, when executed by the processor, cause the processor to interpose on swap-out activity at a head of a swap-out path to detect the swapping activity.
3. The medium of claim 1 , further comprising instructions stored thereon that, when executed by the processor, cause the processor to interpose on input/output (I/O) requests to storage to detect the swapping activity.
4. The medium of claim 1 , wherein the user-space application issues a blocking system call.
5. The medium of claim 1 , further comprising instructions stored thereon that, when executed by the processor, cause the processor to use one or more of sysfs_notify( ) or an eventfd mechanism to awaken a process of the user-space application.
6. The medium of claim 1 , wherein the user-space application sets the threshold condition by at least one of writing to a sysfs node or issuing an ioctl( ) to a special file.
7. The medium of claim 1 , wherein the threshold condition can include one or more of a raw swap count, a mean, a standard deviation, or a moving average.
8. An apparatus comprising a processor and a memory, wherein the memory includes programmed instructions that, when executed by the processor, cause the apparatus to:
receive, from a user-space application, a request to detect swapping activity satisfying a threshold condition, wherein the swapping activity comprises swapping pages of a virtual machine (VM) from a host memory to a storage location shared by multiple VMs, wherein a page table of the VM specifies physical locations of non-swapped pages in the host memory and physical locations of swapped pages in the storage location;
detect the swapping activity satisfying the threshold condition; and
in response to occurrence of the threshold condition, send a response that indicates that the swapping activity satisfies the threshold condition.
9. The apparatus of claim 8 , wherein the memory further includes programmed instructions that, when executed by the processor, cause the apparatus to interpose on swap-out activity at a head of a swap-out path to detect the swapping activity.
10. The apparatus of claim 8 , wherein the memory further includes programmed instructions that, when executed by the processor, cause the apparatus to interpose on input/output (I/O) requests to storage to detect the swapping activity.
11. The apparatus of claim 8 , wherein the user-space application issues a blocking system call.
12. The apparatus of claim 8 , wherein the memory further includes programmed instructions that, when executed by the processor, cause the apparatus to use one or more of sysfs_notify( ) or an eventfd mechanism to awaken a process of the user-space application.
13. The apparatus of claim 8 , wherein the user-space application sets the threshold condition by at least one of writing to a sysfs node or issuing an ioctl( ) to a special file.
14. The apparatus of claim 8 , wherein the threshold condition can include one or more of a raw swap count, a mean, a standard deviation, or a moving average.
15. A computer-implemented method comprising:
receiving, from a user-space application, a request to detect swapping activity satisfying a threshold condition, wherein the swapping activity comprises swapping pages of a virtual machine (VM) from a host memory to a storage location shared by multiple VMs, wherein a page table of the VM specifies physical locations of non-swapped pages in the host memory and physical locations of swapped pages in the storage location;
detecting the swapping activity satisfying the threshold condition; and
in response to occurrence of the threshold condition, sending a response that indicates that the swapping activity satisfies the threshold condition.
16. The method of claim 15 , further comprising interposing on swap-out activity at a head of a swap-out path to detect the swapping activity.
17. The method of claim 15 , further comprising interposing on input/output (I/O) requests to storage to detect the swapping activity.
18. The method of claim 15 , wherein the user-space application issues a blocking system call.
19. The method of claim 15 , further comprising awakening a process of the user-space application.
20. The method of claim 15 , wherein the user-space application sets the threshold condition by at least one of writing to a sysfs node or issuing an ioctl( ) to a special file.