프로세스 스케줄링 SRT 문제 모음

SRT스케줄링은 SRTF스케줄링이라고도 함 선점형 스케줄링 2015 국가다음 표는 단일 CPU에 진입한 프로세스의 도착 시간과 처리하는 데 필요한 실행 시간을 나타낸 것이다.프로세스 간 문맥 교환에 따른 오버헤드는 무시한다고 할 때, SRT(Shortest Remaining Time) 스케줄링 알고리즘을사용한 경우 네 프로세스의 평균 반환시간 (turnaround time)은? <table class="txc-table" width="700" cellspacing="0" cellpadding="0" border="0" style="line-height: 1.6; border-collapse: collapse; border: none;"><tbody><tr style="font-family: 굴림, gulim, tahoma, sans-serif; line-height: 1.6;"><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 233px; height: 24px; border-width: 1px; border-style: solid; border-color: rgb(204, 204, 204);">프로세스 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 233px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204); border-top: 1px solid rgb(204, 204, 204);">도착 시간 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 233px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204); border-top: 1px solid rgb(204, 204, 204);">실행 시간 </td></tr><tr style="font-family: 굴림, gulim, tahoma, sans-serif; line-height: 1.6;"><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 233px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204); border-left: 1px solid rgb(204, 204, 204);">P1 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 233px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204);">0 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 233px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204);">8 </td></tr><tr style="font-family: 굴림, gulim, tahoma, sans-serif; line-height: 1.6;"><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 233px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204); border-left: 1px solid rgb(204, 204, 204);">P2 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 233px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204);">2 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 233px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204);">4 </td></tr><tr style="font-family: 굴림, gulim, tahoma, sans-serif; line-height: 1.6;"><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 233px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204); border-left: 1px solid rgb(204, 204, 204);">P3 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 233px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204);">4 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 233px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204);">1 </td></tr><tr style="font-family: 굴림, gulim, tahoma, sans-serif; line-height: 1.6;"><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 233px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204); border-left: 1px solid rgb(204, 204, 204);">P4 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 233px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204);">6 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 233px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204);">4 </td></tr></tbody></table>① 4.25② 7③ 8.75④ 10답:2평균 반환시간 : (17+5+1+5)/4=7작업진행중 새로운 작업이 들어오면 이전 작업~신규작업의 남은 실행시간 확인후 제일 작은 시간을 실행하는 스케줄링 <table class="txc-table" width="700" cellspacing="0" cellpadding="0" border="0" style="line-height: 1.6; border-collapse: collapse; border: none;"><tbody><tr style="font-family: 굴림, gulim, tahoma, sans-serif; line-height: 1.6;"><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 100px; height: 24px; border-width: 1px; border-style: solid; border-color: rgb(204, 204, 204);">작업 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 100px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204); border-top: 1px solid rgb(204, 204, 204);">P1 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 100px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204); border-top: 1px solid rgb(204, 204, 204);">P2 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 100px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204); border-top: 1px solid rgb(204, 204, 204);">P3 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 100px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204); border-top: 1px solid rgb(204, 204, 204);">P2 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 100px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204); border-top: 1px solid rgb(204, 204, 204);">P4 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 100px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204); border-top: 1px solid rgb(204, 204, 204);">P1 </td></tr><tr style="font-family: 굴림, gulim, tahoma, sans-serif; line-height: 1.6;"><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 100px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204); border-left: 1px solid rgb(204, 204, 204);">시간 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 100px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204);">2 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 100px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204);">4 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 100px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204);">5 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 100px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204);">7 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 100px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204);">11 </td><td style="font-family: 굴림, gulim, tahoma, sans-serif; font-size: 12px; width: 100px; height: 24px; border-bottom: 1px solid rgb(204, 204, 204); border-right: 1px solid rgb(204, 204, 204);">17 </td></tr></tbody></table>반환시간 구하기 : 완료시간-도착시간P1 17-0:17P2 7-2:5P3 5-4:1P4 11-6:51. P1 8초간 실행   P2 도착:2초(P1 2초 지난 시점),   비교:P1 남은시간:6초, P2 남은시간:4초   실행시간이 P2가 덜 걸림 P2 실행2. P2 4초간 실행   P3 도착:4(P2 2초 지난 시점)   비교:P2 남은시간:2초, P3 남은시간:1초, P1 남은시간:6초   실행시간이 P3가 덜 걸림 P3 실행3. P3 1초간 진행(아직 5초밖에 안 되었음 6초에 도착하는 P4는 비교대상에서 제외)   비교:P2 남은시간:2초, P4 남은시간:4초, P1 남은시간:6초   실행시간이 P2가 덜 걸림 P2 실행4. P4 4초간 진행5. P1 6초간 진행