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IAS-Seminar "Isoefficiency in Practice: Configuring and Understanding the Performance of Task-based Applications"

Anfang
03.03.2017 14:30 Uhr
Ende
03.03.2017 15:30 Uhr
Veranstaltungsort
Jülich Supercomputing Centre, Besprechungsraum 1, Geb. 16.3, R. 350
Referent:
Prof. Dr. Felix Wolf, Fachbereich Informatik, TU Darmstadt
Abstract:

Task-based programming offers an elegant way to express units of computation and the dependencies among them, making it easier to distribute the computational load evenly across multiple cores. However, this separation of problem decomposition and parallelism requires a sufficiently large input problem to achieve satisfactory efficiency on a given number of cores. Unfortunately, finding a good match between input size and core count usually requires significant experimentation, which is expensive and sometimes even impractical.

In this talk, we propose an automated empirical method for finding the isoefficiency function of a task-based program, binding efficiency, core count, and the input size in one analytical expression. This allows the latter two to be adjusted according to given (realistic) efficiency objectives. Moreover, we not only find (i) the actual isoefficiency function but also (ii) the function one would yield if the program execution was free of resource contention and (iii) an upper bound that could only be reached if the program was able to maintain its average parallelism throughout its execution. The difference between the three helps to explain low efficiency, and in particular, it helps to differentiate between resource contention and structural conflicts related to task dependencies or scheduling. The insights gained can be used to co-design programs and shared system resources.

Zeit:
Freitag, 3. März 2017, 1430
Ort:
Jülich Supercomputing Centre, Besprechungsraum 1, Geb. 16.3, R. 350
Ankündigung als pdf-Datei:
 Isoefficiency in Practice: Configuring and Understanding the Performance of Task-based Applications (PDF, 30 kB)

Alle Interessierten sind zu diesem Vortrag herzlich eingeladen.
Kontakt: Bernd Mohr, JSC


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