CODEWITHSUNDEEP
c++cparallel-processingopenmpaffinity
Syntactic Fructose
Syntactic Fructose

Reputation: 20076

Software parallelization with OpenMP versus Affinity scheduling?

Scenario: I have an program which can be easily parallelized using OpenMP, lets say the main loop of the program is a for loop and independent data within it, so paralleizing it would be trivial. However currently I don't parallelize it, and instead use affinity scheduling.

This program performs work on some input files specified by a folder in the command line arguments. To run this program in parallel, someone can create a bat file like so:

start \affinity 1 "1" bat1
start \affinity 2 "2" bat2
start \affinity 3 "3" bat3
start \affinity 4 "4" bat4

where bat1 - 4 is a bat file that calls main.exe with a different input folder for each bat file. So in this case there would be 4 instances of main.exe running on input_folder1, input_folder2, input_folder3, input_folder4 respectively.

What would be the benefits of using a library like OpenMP be instead of affinity scheduling? I figure

But would I expect to actually see a performance boost? Why if so?

Upvotes: 0

Views: 107

Answers (1)

Phil Miller
Phil Miller

Reputation: 38118

If your problem is a simply parallel, with no interaction among the data in the separate input files, then you would probably not see a speedup with OpenMP, and might even see a slow-down, since memory allocation and various other things then have to be thread-safe. Single-threaded processes can gain lots of efficiencies, and in fact do on GNU libc, where linking in POSIX threads support means you also get a slower implementation of malloc

Upvotes: 1

Related Questions