This is a multipart blog article series, and in this series I am going to explain you the concepts of operating system. This article series is divided into multiple modules and this is the fifth module which consists of 26 articles.
In this article we will see a question on contiguous memory management and will try to understand its concepts.
Question: Calculate the time at which J7
will be completed. (Algorithm is best-fit)
Request No. | J1 | J2 | J3 | J4 | J5 | J6 | J7 | J8 |
---|---|---|---|---|---|---|---|---|
Request size | 2 KB | 14 KB | 3 KB | 6 KB | 6 KB | 10 KB | 7 KB | 20 KB |
Usage | 4 | 10 | 2 | 8 | 4 | 1 | 8 | 6 |
- 17
- 19
- 20
- 37
Answer:
- (ii) 19
- We will put
J1
at location3
in memory, the internal fragmentation is zero. It will execute for4
unit of time.
- Now, we will put
J2
in memory at location2
, where it will get execute for10 units
of time. At present the internal fragmentation at memory location2
is of6 KB
. - Now, we put
J3
in memory location0
, where it will get executed for2 unit
of time. At present the internal fragmentation at memory location at0
is1 KB
. - Then
J4
will arrive, we put it in memory location1
, where it will get executed for8 units
of time. At present the internal fragmentation at memory location1
is2 KB
. - We want to put
J5
in memory but there is no empty slot. So, we will wait untilJ4
gets terminated and then we will placeJ5
at memory location1
, where it will get executed for4 units
of time. - Now we want to put
J6
in memory but there is no empty slot that can accommodateJ6
. So we will wait tillJ2
gets completed and then we will placeJ6
at memory location2
. Where it will be executed for1 unit
of time. - We want to put
J7
in memory but again there is no empty slot which can accommodateJ7
. So we will wait tillJ6
gets completed and then placeJ7
at memory location2
, where it will get executed for8 unit
of time. - Therefore
J7
will be completed at time unit19
and time at whichJ7
enters RAM is11
.
So this was a simple question of contiguous memory management. Hope you liked it and learned something new from it.
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