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1answer
34 views

Vector clocks: Why is it necessary to increment my clock on receiving a message?

Assume I have a distributed system of entities, each with a replica of the same data object that can be modified by broadcasting the changes and I'm using vector clocks to know how to order changes. ...
36
votes
3answers
4k views

How do computers keep track of time?

How are computers able to tell the exactly correct time and date every time? Whenever I close the computer (shut it down) all connections and processes inside stop. How is it that when I open the ...
1
vote
1answer
54 views

Applying information theory to processor clocks

Has there been any research on the subject of applying information theory to a processors clock? It occurred to me that a clock is actually transmitting data that is used for synchronization of ...
3
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1answer
49 views

How can I calculate the effective bandwidth of a memory system?

I am currently doing my homework for my Computer Architecture class. One of the questions asks: A computer has a 64-bit data bus and 64-bit-wide memory blocks. The memory devices have an access ...
2
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3answers
124 views

How is clock syncing implemented?

I'm looking for an explanation or reference on the implementation of computer clock. To keep the question at the level of logical abstractions: say, we put together some combinational and sequential ...
6
votes
0answers
63 views

What is 2g-precedence?

I am currently reading a couple of papers about event processing. In the context of ordering events, "2g-precedence" is frequently mentioned. I don't know what it is, and I cannot find much ...
6
votes
3answers
316 views

Happened-before and Causal order

I'm reading Lamport's "Time, Clocks, and the Ordering of Events in a Distributed System" and there's a detail that's bugging me. Lamport defines the "happened before" partial order, which I ...
1
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1answer
621 views

Clock skew vs clock offset in the context of clock synchronization network protocols

In the context of clock synchronization among nodes of a network, what is clock offset and what is clock skew? Are these terms synonymous or is there a difference between them?
-1
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1answer
75 views

How was counted one second in computers

I would like to know how was counted 1 second in computers. I mean how machine can understand period of 1 second. Who and when resolved this problem, and more important how ?
4
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1answer
153 views

Lamport Timestamps: When to Update Counters

In the timepiece (excuse the pun) that is Time, Clocks and the Ordering of Events, Lamport describes the logical clock algorithm as the following: Each process $Pi$ increments $Ci$ between any two ...
5
votes
1answer
7k views

What are system clock and CPU clock; and what are their functions?

While reading a book, I came across a paragraph given below: In order to synchronize all of a computer’s operations, a system clock—a small quartz crystal located on the motherboard—is used. ...
5
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1answer
203 views

Visualization of Lamport's three-dimensional “space-time diagram” with introduced “tick lines”

In the third page (the third paragraph in the right column) of the paper "Time, Clocks, and the Ordering of Events in a Distributed System" by Leslie Lamport, it says that The reader may find it ...
3
votes
3answers
192 views

Is there a way to compute time without system clock

I was thinking about any method where we can use RAM I/O speed, to calculate time, let's say for example: RAM transfer rate is 1000 MB/s, so when it's half full (about 500 M Bytes written), by ...
13
votes
1answer
688 views

All soldiers should shoot at the same time

When I was a student, I saw a problem in a digital systems/logic design textbook, about N soldiers standing in a row, and want to shoot at the same time. A more difficult version of the problem was ...
30
votes
5answers
5k views

Clock synchronization in a network with asymmetric delays

Assume a computer has a precise clock which is not initialized. That is, the time on the computer's clock is the real time plus some constant offset. The computer has a network connection and we want ...