On the definition of a theoretical concept of an operating system

We dwell on how a definition of a theoretical concept of an operating system, suitable to be incorporated in a mathematical theory of operating systems, could look like. This is considered a valuable preparation for the development of a mathematical theory of operating systems.Comment: 8 page

The response-time distribution in a real-time database with optimistic concurrency control and exponential execution times

For a real-time shared-memory database with optimistic concurrency control, an approximation for the transaction response-time distribution is obtained. The model assumes that transactions arrive at the database according to a Poisson process, that every transaction takes an exponential execution time and uses an equal number of data-items uniformly chosen, and that the multiprogramming level is bounded. The analysis is based on a decomposition approach: results for the closed system with a fixed number of transactions are used to derive the responsetime distribution in the open system with Poisson arrivals. Numerical experiments that compare analysis with simulation indicate that the approximation for the throughput and the response-time distribution works well for the closed system. For the open system the approximation for the response-time distribution is useful if the load is not too high

The response-time distribution in a real-time database with optimistic concurrency control and constant execution times

For a real-time shared-memory database with optimistic concurrency control, an approximation for the transaction response-time distribution is obtained. The model assumes that transactions arrive at the database according to a Poisson process, that every transaction uses an equal number of data-items uniformly chosen, and that the multiprogramming level is bounded. The execution time of all transactions is constant. The behavior of the system is approximated by an M/D/c queue with feedback. The probability that a transaction must be fed back for a rerun depends on the number of transactions that has committed during its execution. Numerical experiments, which compare the approximative analysis with a simulation of the database, show that the approximation of the response-time distribution is quite accurate, even for high system loads

Accounting of computer system use in EXEC 8

EXEC 8 modified multiprogramming system to log core time and central processing uni

Shared versus distributed memory multiprocessors

The question of whether multiprocessors should have shared or distributed memory has attracted a great deal of attention. Some researchers argue strongly for building distributed memory machines, while others argue just as strongly for programming shared memory multiprocessors. A great deal of research is underway on both types of parallel systems. Special emphasis is placed on systems with a very large number of processors for computation intensive tasks and considers research and implementation trends. It appears that the two types of systems will likely converge to a common form for large scale multiprocessors