Operating system with a single kernel stack per processor
In one embodiment, a method includes storing thread state information associated with the first user-mode thread into a memory space associated with the first user-mode thread when executing in kernel space in response to a first system call by a first-user mode thread, executing first operations corresponding to the first system call on a processor, where data associated with executing the first operations are stored on a kernel stack associated with the processor, determining to pause the execution of the first operations, enqueuing a workload on a schedule queue for resuming execution of the first operations in a future, where the workload comprises data associated with executing a remainder of the first operations, and executing second operations corresponding to a second system call from a second user-mode thread on the processor, where data associated with executing the second operations are stored on the kernel stack associated with the processor.
1. A method comprising, by a kernel-mode thread of an operating system of a computing device:
storing, in response to a first system call by a first-user mode thread, thread state information associated with the first user-mode thread into a memory space associated with the first user-mode thread when executing in kernel space;
executing, on a processor of the computing device, first operations corresponding to the first system call, wherein data associated with executing the first operations are stored on a kernel stack associated with the processor;
determining to pause the execution of the first operations;
enqueuing a workload on a schedule queue for resuming the execution of the first operations in a future, wherein the workload comprises data associated with executing a remainder of the first operations; and
executing, on the processor, second operations corresponding to a second system call from a second user-mode thread, wherein data associated with executing the second operations are stored on the kernel stack associated with the processor.
2. The method of claim 1 , wherein the thread state information associated with the first user-mode thread is a snapshot of register values associated with the processor when the first user-mode thread makes the first system call.
3. The method of claim 1 , wherein the processor is associated with only one kernel-mode thread.
4. The method of claim 1 , wherein the memory space associated with the first user-mode thread is a Thread-Local Storage (TLS) associated with the first user-mode thread.
5. The method of claim 1 , wherein the memory space associated with the first user-mode thread is a Thread Control Block (TCB) associated with the first user-mode thread.
6. The method of claim 1 , wherein determining to pause the execution of the first operations comprises calling a scheduler function, wherein the scheduler function makes a schedule decision among a plurality of workloads in the schedule queue.
7. The method of claim 6 , wherein the schedule decision is made based on one or more scheduling policies.
8. The method of claim 1 , wherein the second operations comprise returning to the second user-mode thread.
9. The method of claim 8 , wherein returning to the second user-mode thread comprises:
retrieving thread state information associated with the second user-mode thread from a memory space associated with the second user-mode thread;
returning results of the second operations to the second system call; and
restoring registers of the processor with the retrieved thread state information.
10. The method of claim 1 , wherein the operating system is a microkernel-based operating system, wherein user-mode threads in the operating system comprise user application threads and service-providing threads.
11. The method of claim 10 , wherein a first service-providing thread provides a particular service to second threads, wherein the second threads comprise other service-providing threads or user application threads.
12. The method of claim 11 , wherein a request for the particular service from one of the second threads to the first service-providing thread is communicated through one of available Inter-Process Communication (IPC) mechanisms.
13. The method of claim 11 , wherein a result of the particular service from the first service-providing thread to one of the second threads is communicated through one of available IPC mechanisms or a shared memory.
14. The method of claim 10 , wherein the service-providing threads comprise device drivers.
15. The method of claim 10 , wherein the user application threads are implemented with an event-driven architecture.
16. One or more computer-readable non-transitory storage media embodying software that is operable by a kernel-mode thread of an operating system of a computing device when executed to:
store, in response to a first system call by a first user-mode thread, thread state information associated with the first user-mode thread into a memory space associated with the first user-mode thread when executing in kernel space;
execute, on a processor of the computing device, first operations corresponding to the first system call, wherein data associated with executing the first operations are stored on a kernel stack associated with the processor;
determine to pause the execution of the first operations;
enqueue a workload on a schedule queue for resuming the execution of the first operations in a future, wherein the workload comprises data associated with executing a remainder of the first operations; and
execute, on the processor, second operations corresponding to a second system call from a second user-mode thread, wherein data associated with executing the second operations are stored on the kernel stack associated with the processor.
17. The media of claim 16 , wherein the thread state information associated with the first user-mode thread is a snapshot of register values associated with the processor when the first user-mode thread makes the first system call.
18. The media of claim 16 , wherein the processor is associated with only one kernel-mode thread.
19. The media of claim 16 , wherein the memory space associated with the first user-mode thread is a Thread-Local Storage (TLS) associated with the first user-mode thread.
20. A system comprising:
one or more processors; and
one or more computer-readable non-transitory storage media coupled to one or more of the processors and comprising instructions operable when executed by one of the processors to cause a kernel-mode thread of an operating system of the system to:
store, in response to a first system call by a first user-mode thread, thread state information associated with the first user-mode thread into a memory space associated with the first user-mode thread when executing in kernel space;
execute, on a processor among the one or more processors, first operations corresponding to the first system call, wherein data associated with executing the first operations are stored on a kernel stack associated with the processor;
determine to pause the execution of the first operations;
enqueue a workload on a schedule queue for resuming the execution of the first operations in a future, wherein the workload comprises data associated with executing a remainder of the first operations; and
execute, on the processor, second operations corresponding to a second system call from a second user-mode thread, wherein data associated with executing the second operations are stored on the kernel stack associated with the processor.