3 Serializability p time p 1 Operation 1 Operation 2 p 2 Operation 3 Rx0 Ry0

3 serializability p time p 1 operation 1 operation 2

This preview shows page 10 - 13 out of 19 pages.

3 Serializability p 0 time p 1 Operation 1 Operation 2 p 2 Operation 3 R(x)0 R(y)0 W(x)1 R(x)1 W(y)2 Can only occur before in an equivalent sequential execution No cycle op1- ->op2- ->op3 in the precedence graph serializable Linearizability
Image of page 10
6/5/18 11 The University of Sydney Page 41 Linearizability Real-time precedence: if an operation o 1 returns before another operation o 2 is invoked (at a potentially different process) then o 1 precedes o 2 with respect (w.r.t) to real-time . Linearizability. The result of each execution is equivalent to a sequential execution that respects the real-time precedence (i.e., in which an operation returning before another is invoked is always ordered before) is the same as if the (read and write) operations by all processes on the same data store were executed in some sequential order and the operations of each individual process appear in this sequence in its program order 4 Linearizability (of reads and writes) [Herlihy and Wing, TOPLAS 1990] p 0 time p 1 R(x)0 W(x)1 inv. resp. inv. resp. R 0 (x)0 precedes W 1 (x)1 w.r.t real time The University of Sydney Page 42 Linearizability. The result of each execution is equivalent to a sequential execution that respects the real-time precedence (i.e., in which an operation returning before another is invoked is always ordered before) is the same as if the (read and write) operations by all processes on the same data store were executed in some sequential order and the operations of each individual process appear in this sequence in its program order Example 5 : is this a linearizable execution? (initially x=0) Linearizability 4 Linearizability (of reads and writes) p 0 time p 1 R(x)0 R(x)0 W(x)1 The University of Sydney Page 43 Linearizability Linearizability. The result of each execution is equivalent to a sequential execution that respects the real-time precedence (i.e., in which an operation returning before another is invoked is always ordered before) is the same as if the (read and write) operations by all processes on the same data store were executed in some sequential order and the operations of each individual process appear in this sequence in its program order Example 5 : this is not a linearizable execution (initially x=0) W 1 (x)1 precedes R 0 (x)0 w.r.t real-time, thus R 0 (x)0 cannot return the initial value of x. 4 Linearizability (of reads and writes) p 0 time p 1 R(x)0 R(x)0 W(x)1 The University of Sydney Page 44 Linearizability Linearizability. The result of each execution is equivalent to a sequential execution that respects the real-time precedence (i.e., in which an operation returning before another is invoked is always ordered before) is the same as if the (read and write) operations by all processes on the same data store were executed in some sequential order and the operations of each individual process appear in this sequence in its program order Example 6 : is this a linearizable execution? (initially x=0) 4 Linearizability (of reads and writes) p 0 time p 1 R(x)0 R(x) 1 W(x)1
Image of page 11
6/5/18 12 The University of Sydney Page 45
Image of page 12
Image of page 13

You've reached the end of your free preview.

Want to read all 19 pages?

  • '19
  • routing protocol, Consistency model

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask You can ask (will expire )
Answers in as fast as 15 minutes
A+ icon
Ask Expert Tutors