How can it be explained that P5's request preceded P7's? What can be said about the scheduler in use, and more generally about the types of schedulers present? What can be said about the state model used?

Time Event 5 P1 requests a read to disc 3 15 P5 s quantum of time ends 18 P7 requests a write to disc 3 20 P3 requests a read to disc 2 24 P5 requests a write to disc 3 28 P5 is suspended 33 disc 2 comunicates using an interrupt, the completion of the request of P3 36 disc 3 comunicates using an interrupt, the completion of the request of P1 38 P8 ends 40 disc 3 comunicates using an interupt, the completion of the request of P5 44 P5 returns to memory 48 disc 3 comunicates using an interrupt, the end of P7 s request