DOC PREVIEW
CMU CS 15213 - Lecture

This preview shows page 1-2-17-18-19-35-36 out of 36 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

Introduction to Computer SystemsIntroduction to Computer SystemsTopics:Topics:Theme and objectiveFive great realities of computer systemsHow this fits within CS curriculumCourse mechanics and overview15-213 S’0601-overview.ppt15-213“The Class That Gives CMU Its Zip!”Frank PfenningJanuary 17, 2006– 2 –15-213, S’06Course ThemeCourse ThemeAbstraction is good, but programs run on real hardware!Courses to date emphasize abstractionCourses to date emphasize abstractionAbstract data typesAsymptotic analysisThese abstractions have limitsThese abstractions have limitsNeed to understand underlying implementationsPerformance (time and space)Useful outcomesUseful outcomesBecome more effective programmersAble to find and eliminate bugs efficientlyAble to tune program performancePrepare for later “systems” classes in CS & ECECompilers, Operating Systems, Networks, Computer Architecture, Embedded Systems– 3 –15-213, S’06Great Reality #1Great Reality #1Int’sInt’sare not Integers, Float’s are not are not Integers, Float’s are not RealsRealsExamplesExamplesIs x2 0?Float’s: Yes!Int’s:» 40000 * 40000 --> 1600000000» 50000 * 50000 --> ??Is (x + y) + z = x + (y + z)?Unsigned & Signed Int’s: Yes!Float’s:» (1e20 + -1e20) + 3.14 --> 3.14» 1e20 + (-1e20 + 3.14) --> ??– 4 –15-213, S’06Computer ArithmeticComputer ArithmeticDoes not generate random valuesDoes not generate random valuesArithmetic operations have important mathematical propertiesCannot assume “usual” propertiesCannot assume “usual” propertiesDue to finiteness of representationsInteger operations satisfy “ring” propertiesCommutativity, associativity, distributivityFloating point operations satisfy “ordering” propertiesMonotonicity, values of signsObservationObservationNeed to understand which abstractions apply in which contextsImportant issues for compiler writers and serious application programmers– 5 –15-213, S’06Great Reality #2Great Reality #2You’ve got to know assemblyYou’ve got to know assemblyChances are, you’ll never write a program in assemblyChances are, you’ll never write a program in assemblyCompilers are much better and more patient than you areUnderstanding assembly key to machineUnderstanding assembly key to machine--level level execution modelexecution modelBehavior of programs in presence of bugsHigh-level language model is inadequateTuning program performanceUnderstanding sources of program inefficiencyImplementing system softwareCompiler has machine code as targetOperating systems must manage process state– 6 –15-213, S’06Measuring TimeMeasuring TimeTrickier than it Might LookTrickier than it Might LookMany sources of variationExampleExampleSum integers from 1 to nn Cycles Cycles/n100 961 9.611,000 8,407 8.411,000 8,426 8.4310,000 82,861 8.2910,000 82,876 8.291,000,000 8,419,907 8.421,000,000 8,425,181 8.431,000,000,000 8,371,2305,591 8.37– 7 –15-213, S’06Great Reality #3Great Reality #3Memory Matters: Memory Matters: Random Access Memory is anRandom Access Memory is anunun--physical abstractionphysical abstractionMemory is not unboundedMemory is not unboundedIt must be allocated and managedMany applications are memory dominatedMemory referencing bugs especially perniciousMemory referencing bugs especially perniciousEffects are distant in both time and spaceMemory performance is not uniformMemory performance is not uniformCache and virtual memory effects can greatly affect program performanceAdapting program to characteristics of memory system can lead to major speed improvements– 8 –15-213, S’06Memory Referencing Bug ExampleMemory Referencing Bug Examplemain (){long int a[2];double d = 3.14;a[2] = 1073741824; /* Out of bounds reference */printf("d = %.15g\n", d);exit(0);}main (){long int a[2];double d = 3.14;a[2] = 1073741824; /* Out of bounds reference */printf("d = %.15g\n", d);exit(0);}Alpha MIPS Linux-g 5.30498947741318e-315 3.1399998664856 3.14-O 3.14 3.14 3.14(Linux version gives correct result, but implementing as separate function gives segmentation fault.)– 9 –15-213, S’06Memory Referencing ErrorsMemory Referencing ErrorsC and C++ do not provide any memory protectionC and C++ do not provide any memory protectionOut of bounds array referencesInvalid pointer valuesAbuses of malloc/freeCan lead to nasty bugsCan lead to nasty bugsWhether or not bug has any effect depends on system and compilerAction at a distanceCorrupted object logically unrelated to one being accessedEffect of bug may be first observed long after it is generatedHow can I deal with this?How can I deal with this?Program in Java, Lisp, ML, or CycloneUnderstand what possible interactions may occurUse or develop tools to detect referencing errors– 10 –15-213, S’06Memory System Performance ExampleMemory System Performance ExampleHierarchical memory organizationPerformance depends on access patternsIncluding how step through multi-dimensional arrayvoid copyji(int src[2048][2048],int dst[2048][2048]){int i,j;for (j = 0; j < 2048; j++)for (i = 0; i < 2048; i++)dst[i][j] = src[i][j];}void copyij(int src[2048][2048],int dst[2048][2048]){int i,j;for (i = 0; i < 2048; i++)for (j = 0; j < 2048; j++)dst[i][j] = src[i][j];}59,393,288 clock cycles 1,277,877,876 clock cycles21.5 times slower!(Measured on 2GHzIntel Pentium 4)– 11 –15-213, S’06The Memory MountainThe Memory Mountains1s3s5s7s9s11s13s158m2m512k128k32k8k2k020040060080010001200Read throughput (MB/s)Stride (words)Working set size (bytes)Pentium III Xeon550 MHz16 KB on-chip L1 d-cache16 KB on-chip L1 i-cache512 KB off-chip unifiedL2 cacheL1L2Memxecopyijcopyji– 12 –15-213, S’06Memory Performance ExampleMemory Performance ExampleImplementations of Matrix MultiplicationImplementations of Matrix MultiplicationMultiple ways to nest loops/* ijk */for (i=0; i<n; i++) {for (j=0; j<n; j++) {sum = 0.0;for (k=0; k<n; k++) sum += a[i][k] * b[k][j];c[i][j] = sum;}} /* ijk */for (i=0; i<n; i++) {for (j=0; j<n; j++) {sum = 0.0;for (k=0; k<n; k++) sum += a[i][k] * b[k][j];c[i][j] = sum;}} /* jik */for (j=0; j<n; j++) {for (i=0; i<n; i++) {sum = 0.0;for (k=0; k<n; k++)sum += a[i][k] * b[k][j];c[i][j] = sum;}}/* jik */for (j=0; j<n; j++) {for (i=0; i<n; i++) {sum = 0.0;for (k=0; k<n; k++)sum += a[i][k] * b[k][j];c[i][j] =


View Full Document

CMU CS 15213 - Lecture

Documents in this Course
lecture

lecture

14 pages

lecture

lecture

46 pages

Caches

Caches

9 pages

lecture

lecture

39 pages

Lecture

Lecture

36 pages

Lecture

Lecture

45 pages

Lecture

Lecture

56 pages

lecture

lecture

11 pages

lecture

lecture

9 pages

Lecture

Lecture

36 pages

Lecture

Lecture

37 pages

Exam

Exam

16 pages

Lecture

Lecture

10 pages

Lecture

Lecture

43 pages

Lecture

Lecture

8 pages

Lecture

Lecture

8 pages

Lecture

Lecture

36 pages

Lecture

Lecture

43 pages

Lecture

Lecture

12 pages

Lecture

Lecture

37 pages

Lecture

Lecture

6 pages

Lecture

Lecture

40 pages

coding

coding

2 pages

Exam

Exam

17 pages

Exam

Exam

14 pages

Lecture

Lecture

29 pages

Lecture

Lecture

34 pages

Exam

Exam

11 pages

Lecture

Lecture

9 pages

Lecture

Lecture

37 pages

Lecture

Lecture

36 pages

lecture

lecture

46 pages

Lecture

Lecture

33 pages

Lecture

Lecture

57 pages

Lecture

Lecture

32 pages

Lecture

Lecture

46 pages

Lecture

Lecture

40 pages

Lecture

Lecture

11 pages

Lecture

Lecture

6 pages

Lecture

Lecture

43 pages

Lecture

Lecture

12 pages

Lecture

Lecture

18 pages

Exam

Exam

10 pages

Lecture

Lecture

45 pages

Lecture

Lecture

37 pages

Exam

Exam

24 pages

class09

class09

21 pages

class22

class22

37 pages

class20

class20

30 pages

class27

class27

33 pages

class25

class25

21 pages

class04

class04

31 pages

Lecture

Lecture

59 pages

class01a

class01a

14 pages

class12

class12

45 pages

class29

class29

33 pages

Lecture

Lecture

39 pages

Lecture

Lecture

6 pages

class03

class03

34 pages

lecture

lecture

42 pages

Lecture

Lecture

40 pages

Lecture

Lecture

47 pages

Exam

Exam

19 pages

R06-B

R06-B

25 pages

class17

class17

37 pages

class25

class25

31 pages

Lecture

Lecture

15 pages

final-f06

final-f06

17 pages

Lecture

Lecture

9 pages

lecture

lecture

9 pages

Exam

Exam

15 pages

Lecture

Lecture

22 pages

class11

class11

45 pages

lecture

lecture

50 pages

Linking

Linking

37 pages

Lecture

Lecture

64 pages

Integers

Integers

40 pages

Exam

Exam

11 pages

Lecture

Lecture

37 pages

Lecture

Lecture

44 pages

Lecture

Lecture

37 pages

Lecture

Lecture

9 pages

Lecture

Lecture

37 pages

Lecture

Lecture

45 pages

Final

Final

25 pages

lecture

lecture

9 pages

Lecture

Lecture

30 pages

Lecture

Lecture

16 pages

Final

Final

17 pages

Lecture

Lecture

8 pages

Exam

Exam

11 pages

Lecture

Lecture

47 pages

Lecture

Lecture

9 pages

lecture

lecture

39 pages

Exam

Exam

11 pages

lecture

lecture

41 pages

lecture

lecture

37 pages

Lecture

Lecture

59 pages

Lecture

Lecture

45 pages

Exam 1

Exam 1

18 pages

Lecture

Lecture

41 pages

Lecture

Lecture

32 pages

Lecture

Lecture

30 pages

Lecture

Lecture

9 pages

Lecture

Lecture

9 pages

Lecture

Lecture

15 pages

Lecture

Lecture

11 pages

Lecture

Lecture

9 pages

Lecture

Lecture

34 pages

Lecture

Lecture

40 pages

Lecture

Lecture

4 pages

Lecture

Lecture

46 pages

Lecture

Lecture

8 pages

Lecture

Lecture

65 pages

Lecture

Lecture

38 pages

Lecture

Lecture

35 pages

Lecture

Lecture

8 pages

Lecture

Lecture

34 pages

Lecture

Lecture

8 pages

Exam

Exam

13 pages

Lecture

Lecture

43 pages

Lecture

Lecture

9 pages

Lecture

Lecture

12 pages

Lecture

Lecture

9 pages

Lecture

Lecture

34 pages

Lecture

Lecture

43 pages

Lecture

Lecture

7 pages

Lecture

Lecture

45 pages

Lecture

Lecture

24 pages

Lecture

Lecture

47 pages

Lecture

Lecture

12 pages

Lecture

Lecture

20 pages

Lecture

Lecture

9 pages

Exam

Exam

11 pages

Lecture

Lecture

52 pages

Lecture

Lecture

20 pages

Exam

Exam

11 pages

Lecture

Lecture

35 pages

Lecture

Lecture

47 pages

Lecture

Lecture

18 pages

Lecture

Lecture

30 pages

Lecture

Lecture

59 pages

Lecture

Lecture

37 pages

Lecture

Lecture

22 pages

Lecture

Lecture

35 pages

Exam

Exam

23 pages

Lecture

Lecture

9 pages

Lecture

Lecture

22 pages

class12

class12

32 pages

Lecture

Lecture

8 pages

Lecture

Lecture

39 pages

Lecture

Lecture

44 pages

Lecture

Lecture

38 pages

Lecture

Lecture

69 pages

Lecture

Lecture

41 pages

Lecture

Lecture

12 pages

Lecture

Lecture

52 pages

Lecture

Lecture

59 pages

Lecture

Lecture

39 pages

Lecture

Lecture

83 pages

Lecture

Lecture

59 pages

class01b

class01b

17 pages

Exam

Exam

21 pages

class07

class07

47 pages

Lecture

Lecture

11 pages

Odyssey

Odyssey

18 pages

multicore

multicore

66 pages

Lecture

Lecture

6 pages

lecture

lecture

41 pages

lecture

lecture

55 pages

lecture

lecture

52 pages

lecture

lecture

33 pages

lecture

lecture

46 pages

lecture

lecture

55 pages

lecture

lecture

17 pages

lecture

lecture

49 pages

Exam

Exam

17 pages

lecture

lecture

56 pages

Exam 2

Exam 2

16 pages

Exam 2

Exam 2

16 pages

Notes

Notes

37 pages

Lecture

Lecture

40 pages

Lecture

Lecture

36 pages

Lecture

Lecture

43 pages

Lecture

Lecture

25 pages

Exam

Exam

13 pages

Lecture

Lecture

32 pages

Lecture

Lecture

12 pages

Lecture

Lecture

58 pages

Lecture

Lecture

29 pages

Lecture

Lecture

59 pages

Lecture

Lecture

41 pages

Lecture

Lecture

50 pages

Exam

Exam

17 pages

Lecture

Lecture

29 pages

Lecture

Lecture

44 pages

Lecture

Lecture

41 pages

Lecture

Lecture

52 pages

Lecture

Lecture

40 pages

Lecture

Lecture

33 pages

lecture

lecture

10 pages

Lecture

Lecture

27 pages

Lecture

Lecture

29 pages

Lecture

Lecture

39 pages

Lecture

Lecture

9 pages

Lecture

Lecture

29 pages

Lecture

Lecture

8 pages

Lecture

Lecture

43 pages

Lecture

Lecture

43 pages

Lecture

Lecture

75 pages

Lecture

Lecture

55 pages

Exam

Exam

12 pages

Lecture

Lecture

43 pages

Lecture

Lecture

35 pages

lecture

lecture

36 pages

Exam

Exam

33 pages

lecture

lecture

56 pages

lecture

lecture

64 pages

lecture

lecture

8 pages

Exam

Exam

14 pages

Lecture

Lecture

43 pages

Lecture

Lecture

36 pages

lecture

lecture

56 pages

lecture

lecture

75 pages

lecture

lecture

36 pages

Lecture

Lecture

50 pages

Lecture

Lecture

45 pages

Lecture

Lecture

13 pages

Exam

Exam

23 pages

Lecture

Lecture

10 pages

Lecture

Lecture

48 pages

Lecture

Lecture

83 pages

lecture

lecture

57 pages

Lecture

Lecture

33 pages

Lecture

Lecture

39 pages

Lecture

Lecture

33 pages

lecture

lecture

54 pages

Lecture

Lecture

30 pages

Exam

Exam

13 pages

Lecture

Lecture

36 pages

Lecture

Lecture

40 pages

Exam

Exam

17 pages

Lecture

Lecture

9 pages

Exam

Exam

15 pages

Lecture

Lecture

44 pages

Lecture

Lecture

34 pages

Lecture

Lecture

24 pages

Lecture

Lecture

29 pages

class12

class12

43 pages

lecture

lecture

43 pages

class22

class22

22 pages

R06-B

R06-B

25 pages

class01b

class01b

19 pages

lecture

lecture

29 pages

lab1

lab1

8 pages

Caches

Caches

36 pages

lecture

lecture

55 pages

Lecture,

Lecture,

37 pages

Integers

Integers

40 pages

Linking

Linking

38 pages

lecture

lecture

45 pages

Lecture

Lecture

61 pages

Linking

Linking

33 pages

lecture

lecture

40 pages

lecture

lecture

40 pages

Lecture

Lecture

32 pages

lecture

lecture

48 pages

lecture

lecture

44 pages

Exam

Exam

11 pages

Lecture

Lecture

31 pages

Lecture

Lecture

46 pages

Lecture

Lecture

40 pages

Lecture

Lecture

40 pages

Exam

Exam

12 pages

Lecture

Lecture

42 pages

Lecture

Lecture

36 pages

Lecture

Lecture

45 pages

Lecture

Lecture

41 pages

Lecture

Lecture

13 pages

Lecture

Lecture

35 pages

Lecture

Lecture

20 pages

Final

Final

19 pages

Lecture

Lecture

33 pages

Lecture

Lecture

50 pages

Lecture

Lecture

33 pages

Lecture

Lecture

27 pages

Lecture

Lecture

6 pages

Exam

Exam

15 pages

Lecture

Lecture

24 pages

Lecture

Lecture

23 pages

Lecture

Lecture

43 pages

Lecture

Lecture

32 pages

Lecture

Lecture

52 pages

Lecture

Lecture

37 pages

Lecture

Lecture

36 pages

Lecture

Lecture

34 pages

Lecture

Lecture

40 pages

Lecture

Lecture

15 pages

lecture

lecture

21 pages

Lecture

Lecture

58 pages

Lecture

Lecture

49 pages

Lecture

Lecture

36 pages

Lecture

Lecture

11 pages

Lecture

Lecture

12 pages

Lecture

Lecture

58 pages

Lecture

Lecture

33 pages

Exam

Exam

15 pages

Lecture

Lecture

35 pages

Lecture

Lecture

10 pages

Lecture

Lecture

25 pages

Lecture

Lecture

31 pages

Lecture

Lecture

24 pages

Lecture

Lecture

34 pages

Lecture

Lecture

50 pages

lecture

lecture

35 pages

Lecture

Lecture

11 pages

Lecture

Lecture

39 pages

Lecture

Lecture

45 pages

Lecture

Lecture

41 pages

exam1-f05

exam1-f05

11 pages

Lecture

Lecture

4 pages

Lecture

Lecture

17 pages

Exam

Exam

17 pages

malloc()

malloc()

12 pages

Lecture

Lecture

57 pages

Lecture

Lecture

30 pages

Lecture

Lecture

30 pages

Lecture

Lecture

47 pages

Lecture

Lecture

33 pages

Exam

Exam

12 pages

Lecture

Lecture

43 pages

Lectures

Lectures

33 pages

lecture

lecture

33 pages

Exam

Exam

14 pages

Lecture

Lecture

43 pages

Lecture

Lecture

25 pages

Load more
Download Lecture
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Lecture and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Lecture 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?