Blog

Two independent foggy sightings (both report pink): Z1=Z2=1, baseline priors.Compute P (RS | Z1=Z2=1).

Paravirtualization The context for this question is the same as the previous question. Above picture shows the I/O ring data structure used in Xen to facilitate communication between the guest OS and Xen.  Guest-OS places a request in the I/O ring using the “Request Producer” pointer. Xen places a response in the I/O ring using the “Response Producer” pointer.  [2 points] Why does Xen typically not run out of space to place a response on this ring? State the invariant briefly.

Microkernel [3 points] Greg, a core Linux contributor, is skeptical about Microkernel. He mentions that the 100x cost of the Protected Procedure Calls between different servers due to Address-Space Switching are too high to be able to achieve good performance. Provide two points as counterarguments to Greg’s point of view.

Microkernel You are building an OS using a microkernel-based approach following the principles of the L3 microkernel. The processor architecture you are building this OS for has the following features:  A 32-bit hardware address space.  Paged virtual memory system (8KB pages) with a processor register called PTBR that points to the page table in memory to enable hardware address translation.  A TLB that doesn’t support tagging entries with address space IDs  A pair of hardware-enforced segment registers (lower and upper bound of virtual addresses) which limit the virtual address space that can be accessed by a process running on the processor.  A virtually-indexed physically tagged processor cache.  You end up with the following subsystems that each need to be a separate protection domain.  A: 2^30 bytes  B: 2^30 bytes  C: 100 * 2^20 bytes  D: 500 * 2^20 bytes  E: 1000 * 2^20 bytes  F: 2000 * 2^20 bytes These subsystems are packed into two hardware address spaces: protection domains A and B in the first; and protection domains C, D, E, and F in the second. Based on this grouping, answer the following questions. [2 points] There is a context switch from A to B. What does your OS do to facilitate this context switch? 

Microkernel [2 points] Mention two advantages of Microkernel Approach over Monolith Kernels.

Compute p(x | C2) at x = 2.

At temperature T = 2.5, the algorithm proposes a single uphill move with ∆E = 1.2. Question: What is the acceptance probability?

Write pseudocode to implement the ROI pooling forward pass logic for a single 2D data sample (no batches). Clearly mark your inputs, your outputs, and your parameters. No need to handle special edge cases. Using numpy calls/syntax is allowed. Points may be deducted for lengthy solutions. roi_pooling_forward() { return }

A PTA is encouraging a patient to maintain their home exercise program. Which statement BEST reflects motivational interviewing principles?

Which of the following is a common sign or symptom of chronic obstructive pulmonary disease (COPD)?