I understand most concepts regard a resource allocation graph but I see that some resources have more dots (not sure what they are actually referred to) in them than others such as the example below, R1 and R3 have one dot, R2 has two dots and R4 has three dots. I cannot find anything online that explains this so I would just like to know, how would you determine how many dots should be in a resource when drawing the graph?enter image description here


The dots represent the number of clients a resource can serve simultaneously. So, in the example in the question, resources $R_1$ and $R_3$ can only serve one client at a time, $R_2$ can serve two and $R_4$ can serve up to three clients at the same time.

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  • $\begingroup$ But would I need to be given that kind of information when drawing the graph? If that is the case and such information is not provided would I just assume that each resource can only serve one client at a time? Or lets say each process uses three resources at a time, would that mean each resource would have three dots in it? $\endgroup$ – Osiris93 Sep 1 '15 at 11:27
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    $\begingroup$ I suggest you carefully read the definitions you're working from. The graph represents the state of the processes and resources so, yes, you need to be told how many clients each resource can serve simultaneously, just as you need to be told how many resources there are. Processes don't have dots: only resources. $\endgroup$ – David Richerby Sep 1 '15 at 11:49
  • $\begingroup$ So bottom line if it states that three processes need to access three resources at a time and it doesn't mention anything else, then I will assume that each resource can only serve one client at a time? $\endgroup$ – Osiris93 Sep 1 '15 at 12:02
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    $\begingroup$ @Osiris93 I'm not psychic. Ask the person who set you the question. $\endgroup$ – David Richerby Sep 1 '15 at 12:07
  • $\begingroup$ Okay well thank you for your time, this has helped me a bit :) $\endgroup$ – Osiris93 Sep 1 '15 at 12:12

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