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操作系統課程設計報告模擬進(jìn)程調度程序(一)
此設計報告是對操作系統中進(jìn)程調度的兩種算法，即靜態(tài)優(yōu)先權調度算法和需要時(shí)間片的轉法進(jìn)行了描述，并分析了它們的工作機理。
最高優(yōu)先權調度算法的基本思想是把CPU分配給就緒隊列中優(yōu)先權最高的進(jìn)程。靜態(tài)優(yōu)先數是在創(chuàng )建進(jìn)程時(shí)確定的，并在整個(gè)進(jìn)程運行期間不再改變。
簡(jiǎn)單輪轉法的基本思想是：所有就緒進(jìn)程按 FCFS排成一個(gè)隊列，總是把處理機分配給隊首的進(jìn)程，各進(jìn)程占用CPU的時(shí)間片相同。如果運行進(jìn)程用完它的時(shí)間片后還未完成，就把它送回到就緒隊列的末尾，把處理機重新分配給隊首的進(jìn)程，直至所有的進(jìn)程運行完畢。
然后用具體語(yǔ)言模擬了一個(gè)進(jìn)程調度的程序。用戶(hù)可以自己輸入產(chǎn)生進(jìn)程，然后選擇調度方式進(jìn)行調度。所用的語(yǔ)言為VisualBasic.Net，結果顯示了調度運行過(guò)程。
問(wèn)題描述和分析 ……………………………………………… 4
算法設計 …………………………………………………… 5
源代碼及說(shuō)明 ………………………………………………… 5
結果與分析 ………………………………………………………17
參考文獻……………………………………………………… 18
一、問(wèn)題描述和分析
問(wèn)題描述
CPU調度是多道程序操作系統的基礎，幾乎所有計算機資源在使用前都要被調度，因此，CPU調度對于操作系統來(lái)說(shuō)非常重要。
假如操作系統中存在若干進(jìn)程，這些進(jìn)程，將會(huì )被按照指定的調度方式，由CPU進(jìn)行調度。
本程序，用來(lái)模擬實(shí)現操作系統中的兩種調度方法，即：優(yōu)先權調度和輪轉法調度。
下面對四種調度方法進(jìn)行描述
優(yōu)先權調度（priority-scheduling algorithm）：在這種方式下，每一個(gè)進(jìn)程都有一個(gè)優(yōu)先權與其關(guān)聯(lián)，具有最高優(yōu)先權的進(jìn)程會(huì )被分配到CPU，具有相同優(yōu)先權的進(jìn)程按FCFS順序調度。
輪轉法（round-robin）：這種調度方式是專(zhuān)門(mén)為分時(shí)系統而設計的。它類(lèi)似于FCFS調度，但是增加了搶占以在進(jìn)程是。定義一個(gè)較小時(shí)間單元，稱(chēng)為時(shí)間量或時(shí)間片。時(shí)間片通常為10ms到100ms。為每個(gè)進(jìn)程分配不超過(guò)一個(gè)時(shí)間片間隔的CPU。
分析
根據描述確定解決方法。本程序利用VisualBasic.Net語(yǔ)言實(shí)現。首先定義一個(gè)進(jìn)程的類(lèi)，包括進(jìn)程名、達到時(shí)間、服務(wù)時(shí)間、優(yōu)先權。再定義一個(gè)調度類(lèi)，用以實(shí)現調度算法。
最后在主程序中，用戶(hù)可選擇兩種調度算法,確定問(wèn)題的類(lèi)型。
二、算法設計
主要設計思想
在主程序中，通過(guò)選擇結構，調用兩種調度算法。
各種調度算法實(shí)現
首先建立一個(gè)進(jìn)程類(lèi), 然后建立一個(gè)調度類(lèi)，通過(guò)這個(gè)類(lèi)來(lái)執行調度算法。再建立一個(gè)鏈表，用來(lái)存放這些進(jìn)程。
優(yōu)先權調度：在優(yōu)先權調度中，每產(chǎn)生一個(gè)進(jìn)程，程序會(huì )記錄進(jìn)程的優(yōu)先權，然后按產(chǎn)生的先后順序插入。當當前進(jìn)程結束時(shí)，程序從鏈表中取出一個(gè)優(yōu)先權最高的進(jìn)程執行。
輪轉法調度：由用戶(hù)定義一個(gè)時(shí)間片。在每個(gè)時(shí)間片中，程序執行一個(gè)進(jìn)程。當時(shí)間片結束后，程序將結束當前執行的進(jìn)程，從鏈表中調入下一個(gè)進(jìn)程，并將當前執行的進(jìn)程插入到鏈表尾部。整個(gè)鏈表相當于一個(gè)循環(huán)隊列。
三、源代碼及說(shuō)明
1優(yōu)先級調度算法源代碼
Dim a As Integer
Dim b As Integer
Dim c As Integer
Dim d As Integer
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
If Label7.Width < 200 Then
Label7.Visible = True
Label7.Width += 10
Label17.Visible = True
Label16.Visible = False
Label18.Visible = False
Else
Label17.Visible = False
Label18.Visible = False
Label16.Visible = True
a = 6
End If
If a < b And a < c And a < d Then
Timer1.Enabled = True
End If
If b < a And b < c And b < d Then
Timer2.Enabled = True
End If
If c < a And c < b And c < d Then
Timer3.Enabled = True
End If
If d < a And d < b And d < c Then
Timer4.Enabled = True
End If
End Sub
Private Sub Timer2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick
If Label8.Width < 200 Then
Label8.Visible = True
Label8.Width += 10
Label20.Visible = True
Label19.Visible = False
Label21.Visible = False
Else
Label20.Visible = False
Label21.Visible = False
Label19.Visible = True
b = 7
End If
If a < b And a < c And a < d Then
Timer1.Enabled = True
End If
If b < a And b < c And b < d Then
Timer2.Enabled = True
End If
If c < a And c < b And c < d Then
Timer3.Enabled = True
End If
If d < a And d < b And d < c Then
Timer4.Enabled = True
End If
End Sub
Private Sub Timer3_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer3.Tick
If Label9.Width < 200 Then
Label9.Visible = True
Label9.Width += 10
Label23.Visible = True
Label22.Visible = False
Label24.Visible = False
Else
Label23.Visible = False
Label24.Visible = False
Label22.Visible = True
c = 8
End If
If a < b And a < c And a < d Then
Timer1.Enabled = True
End If
If b < a And b < c And b < d Then
Timer2.Enabled = True
End If
If c < a And c < b And c < d Then
Timer3.Enabled = True
End If
If d < a And d < b And d < c Then
Timer4.Enabled = True
End If
End Sub
Private Sub Timer4_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer4.Tick
If Label10.Width < 200 Then
Label10.Visible = True
Label10.Width += 10
Label26.Visible = True
Label25.Visible = False
Label27.Visible = False
Else
Label26.Visible = False
Label27.Visible = False
Label25.Visible = True
d = 9
End If
If a < b And a < c And a < d Then
Timer1.Enabled = True
End If
If b < a And b < c And b < d Then
Timer2.Enabled = True
End If
If c < a And c < b And c < d Then
Timer3.Enabled =True
End If
If d < a And d < b And d < c Then
Timer4.Enabled = True
End If
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Me.Close()
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
a = TextBox1.Text
b = TextBox2.Text
c = TextBox3.Text
d = TextBox4.Text
If a < b And a < c And a < d Then
Timer1.Enabled = True
End If
If b < a And b < c And b < d Then
Timer2.Enabled = True
End If
If c < a And c < b And c < d Then
Timer3.Enabled = True
End If
If d < a And d < b And d < c Then
Timer4.Enabled = True
End If
TextBox1.Enabled = False
TextBox2.Enabled = False
TextBox3.Enabled = False
TextBox4.Enabled = False
Button1.Enabled = False
Button2.Enabled = True
Label18.Visible = True
Label21.Visible = True
Label24.Visible = True
Label27.Visible = True
End Sub
End Class
2輪轉法調度源代碼
'
Dim a As Integer
Dim b As Integer
Dim c As Integer
Dim d As Integer
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Me.Close()
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
a = TextBox1.Text
b = TextBox2.Text
c = TextBox3.Text
d = TextBox4.Text
If a > 0 And b > 0 And c > 0 And d > 0 Then
Timer1.Enabled() = True
End If
End Sub
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
Dim i As Integer
i = a - Label7.Width
If i < 20 Then
Label7.Width = Label7.Width + i
Label18.Visible = False
Label17.Visible = False
Label16.Visible = True
Timer1.Enabled = False
Timer2.Enabled = True
End If
If Label7.Width < a Then
Label7.Width = Label7.Width + 10
Label18.Visible = True
Label17.Visible = False
Label16.Visible = False
Timer1.Enabled = False
Timer2.Enabled = True
Else
Label18.Visible = False
Label17.Visible = False
Label16.Visible = True
Timer1.Enabled = False
Timer2.Enabled = True
End If
If Label8.Width >= b Then
Label21.Visible = False
Label20.Visible = False
Label19.Visible = True
Else
Label21.Visible = False
Label20.Visible = True
Label19.Visible = False
End If
If Label7.Width < a And Label8.Width >= b And Label9.Width >= c And Label10.Width >= d Then
Label18.Visible = False
Label17.Visible = True
Label16.Visible = False
ElseIf Label29.Width = a Then
Label18.Visible = False
Label17.Visible = False
Label16.Visible = True
End If
End Sub
Private Sub Timer2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick
Dim i As Integer
i = b - Label8.Width
If i < 20 Then
Label8.Width += i
Label21.Visible = False
Label20.Visible = False
Label19.Visible = True
Timer2.Enabled = False
Timer3.Enabled = True
End If
If Label8.Width < b Then
Label8.Width += 10
Label21.Visible = True
Label20.Visible = False
Label19.Visible = False
Timer2.Enabled = False
Timer3.Enabled = True
Else
Label21.Visible = False
Label20.Visible = False
Label19.Visible = True
Timer2.Enabled = False
Timer3.Enabled = True
End If
If Label9.Width >= c Then
Label24.Visible = False
Label23.Visible = False
Label22.Visible = True
Else
Label24.Visible = False
Label23.Visible = True
Label22.Visible = False
End If
If Label8.Width < b And Label7.Width >= a And Label9.Width >= c And Label10.Width >= d Then
Label21.Visible = False
Label20.Visible = True
Label19.Visible = False
ElseIf Label8.Width = b Then
Label21.Visible = False
Label20.Visible = False
Label19.Visible = True
End If
End Sub
Private Sub Timer3_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer3.Tick
Dim i As Integer
i = c - Label9.Width
If i < 20 Then
Label9.Width += i
Label24.Visible = False
Label23.Visible = False
Label22.Visible = True
Timer3.Enabled = False
Timer4.Enabled = True
End If
If Label9.Width < c Then
Label9.Width += 10
Label24.Visible = True
Label23.Visible = False
Label22.Visible = False
Timer3.Enabled = False
Timer4.Enabled = True
Else
&nbnbsp; Label27.Visible = True
Label26.Visible = False
Label25.Visible = False
Timer4.Enabled = False
Timer1.Enabled = True
Else
Label27.Visible = False
Label26.Visible = False
Label25.Visible = True
Timer4.Enabled = False
Timer1.Enabled = True
End If
If Label7.Width >= a Then
Label18.Visible = False
Label17.Visible = False
Label16.Visible = True
Else
Label18.Visible = False
Label17.Visible = True
Label16.Visible = False
End If
If Label10.Width < d And Label7.Width >= a And Label8.Width >= b And Label9.Width >= c Then
Label27.Visible = False
Label26.Visible = True
Label25.Visible = False
ElseIf Label10.Width = d Then
Label27.Visible = False
Label26.Visible = False
Label25.Visible = True
End If
End Sub
Private Sub Form5_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
End Sub
End Class
四、結果與討論
1優(yōu)先權調度算法結果圖
2 輪轉法的程序結果圖
5.結果分析：
經(jīng)選擇調度算法后，每種調度算法都能成功地執行。所以，本次課程設計成功。 五、參考文獻
1、《Windows操作系統原理》 陳向群等著(zhù) 機械工業(yè)出版社
2、《VisualBasic.Net程序設計》馮博琴 崔舒寧著(zhù) 清華大學(xué)出版社
3、《操作系統 原理·技術(shù)與編程》 蔣靜, 徐志偉著(zhù) 機械工業(yè)出版社
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