Self doubt

Question

Is CONVOY Effect possible in "Longest job first" non preemptive scheduling policy ?

Answer 1

Convoy effect can be seen in non preemptive scheduling(FCFS).

If there are two processes P1 with burst time 2, P2 with 20 and if P2 is with CPU, when P2 doing I/O P1 cannot execute whereas in any type of preemptive scheduling we can immediately schedule other process.

Longest job first (Non preemptive) suffer from convoy.

Longest remaining time first will not suffer from convoy as CPU will be utilized efficiently.

Comments

@tusharp FCFS - yes

SJF - Yes

SRTF - No

LJF - Yes

LRTF - No

Prio (non pre) - Yes

Prio(pre) - Yes

Answer 2

It is possible.

When a process with high burst time arrives it will keep the cpu busy leading to convoy effect.

https://gateoverflow.in/237015/operating-systems-conceptz

Can LRTF lead to it? Yes

Good read: https://gateoverflow.in/89982/which-of-the-following-algorithm-leads-convoy-effect