Operating Systems. OS. In MIMD systems, several processors are active simultaneously and all processors in execution must be coordinated by the operating system (OS). The OS’s functions are similar to those of SISD machines. OS. The major functions of multiprocessor OS are the following:
Alternatives for blocking and buffering in message passing.
Distributed Shared Memory Systems
Why is (a) okay?
Why is (a) okay? Because even though it appears the write operation setting x to b appears to have taken place before the write operation setting x to a both P3 and P4 see it the same.
What about (b)?
Should be R(x)b
Updates are done at the release point
Same as release consistency
except updates are done at the acquire.
False sharing of a page between two independent processes.
int *x; //shared variable
. . .
a = *x + b;
adsm_refresh_now( void *ptr ); and
adsm_flush_now( void *ptr );
adsm_prefetch( void *ptr )
adsm_atomic(void *ptr, char *expression);
int *x = (int*)adsm_malloc)”x”,sizeofint(int));
void adsm_collect_begin(void *ptr, int num);
void adsm_collect_end(void *ptr);
int partial_sum = ... ; // calculate the partial sum
sum+=partial_sum; //add partial sum
adsm_collect_end(sum); //total; sum is returned
General structure of a network operating system.
Two clients and a server in a network operating system.
Different clients may mount the servers in different places.
General structure of a distributed system as middleware.
In an open middleware-based distributed system, the protocols used by each middleware layer should be the same, as well as the interfaces they offer to applications.
A comparison between multiprocessor operating systems, multicomputer operating systems, network operating systems, and middleware based distributed systems.