Download Questions 1. Are microkernel based operating systems more secure as it... of code running in privileged mode to a few thousand...

Questions
1. Are microkernel based operating systems more secure as it reduces the amount
of code running in privileged mode to a few thousand lines of code?
Ans. Reducing the amount of code running in privileged mode is a good bestpractice. However it is one of about 1000 other things which could contribute to
making a non-secure OS build.
So I would argue that it does result in a more secure operating system - all other
things being equal. However that is a very big condition
2. What are the advantages of micro kernel design over monolithic design?
Ans .Maintenance is generally easier. Patches can be tested in a separate instance,
and then swapped in to take over a production instance.
b. Rapid development time, new software can be tested without having to reboot
the kernel.
3. What is a thread?
Ans.Thread is an activity executing inside an address space.
4. Determine the effect of L1 and L2 cache on performance?
Ans. Increasing size of L1 data cache does not improve performance on MTs. Even
if it decreases cache misses, no need for such a cost.
Performance is highly related with L2 cache miss ratio, so our scheduling
algorithm should be targeted to decrease cache misses on L2.
5. What is CMT?
Ans. CMT (Multithreaded Chip Multiprocessor) is a new generation of processors
that exploit thread level parallelism to mask the memory latency in modern
workloads.
6. How does active network works?
Ans. Active network architecture is composed of execution a node operating
system capable of supporting one or more execution environments. It also consists
of active hardware, capable of routing or switching as well as executing code
within active packets. This differs from the traditional network architecture which
seeks robustness and stability by attempting to remove complexity and the ability
to change its fundamental operation from underlying network components.
Network processors are one means of implementing active networking concepts.
Active networks have also been implemented as overlay networks.
7. What does an active network offer?
Ans. Active networking allows the possibility of highly tailored and rapid "realtime" changes to the underlying network operation.
8. Explain Lazy release consistency?
Ans. The most frequently used consistency model in software DSM is Lazy
Release Consistency (LRC) in which the invalidations are propagated at acquire
time. Acquire and releases are the two explicit synchronization operations required
in release consistency model and correspond to lock acquire and lock release
respectively. A barrier is a global synchronization operation, implemented as a
release followed by an acquire. In LRC, the updates are detected in software by
computing diffs between the dirty page and a snapshot of the clean copy of the
page.
9.What is Spring?
Ans. Spring was an experimental microkernel-based object oriented operating
system developed at Sun Microsystems.It has its emphasis on interfaces between
modules,most services are implemented in user space.
10. Describe Spring Kernel?
Ans. The spring kernel was divided into two parts: a virtual memory system and
the nucleus. Although the nucleus is equivalent to only one portion of the Mach
kernel, the kernels of each OS are analogous enough to be considered to perform
the same function.
The Spring kernel includes only the most basic functionality and state needed to
support user-side applications. Primarily this includes state to maintain lists of
running programs (domains) and their threads, as well as the communications links
between them (doors).
The spring kernel is not multi-threaded.
11.What is the use of IDL in Spring Operating system?
Ans. The unifying principle of spring is that all key interfaces are defined in an
interface definition language called IDL.This language is object oriented and
include support for multiple inheritance.
12. What are the performance overheads of subcontract?
Ans.Subcontract has some performance cost over simpler RPC systems. Each
object invocation always require an additional two indirect procedure call.
Transmitting an object requires an extra pair of call for marshaling and
unmarshalling.
13. How to reduce cache misses?
Ans. Run task on processor with most “affinity”.
14. What is the problem with greedy schedulers?
Ans. Greedy” schedulers (low CRT) give high throughput and low response times,
but can be unfair & produce high variance in response time.
15.How does exokernel architecture prevents errors in one library operating system
from affecting another ?
Ans. By separating protection from resource management.
16.In what ways checkpoint help?
Ans. checkpoint reduces the amount of work that must be done again at the event
of failure which is good for long transactions