线程化编程方法学 课件.ppt

* Purpose of the Slide Refers students to the 5th lab activity, whose purpose (as stated on the slide) is to correct the race conditions discovered in the primes code. The resulting image is then checked for results and performance. Details Detailed instructions are provided in the student lab manual. Students will use the critical sections technique described on the previous slide. * Purpose of the Slide Show that the critical sections method fixed the bug, but the performance is lower than expected. Details The slide shows a correct answer, but remind the students that this does not guarantee there is no bug (race conditions, if present, may show up only rarely). To be more rigorous, one would re-run Parallel Inspector. * Purpose of the Slide To list some common performance issues (follow up to previous slide, which showed poor threading performance). Details This slide and previous set us up for the final section of this module, performance tuning, which begins on the next slide. * Purpose of the Slide Introduce Parallel Amplifier as a tool to address threading performance; outline its implementation. * * * * * * Purpose of the Slide Gives additional analysis regarding the Timeline and source views shown in the previous slide; identifies a significant bottleneck in the code. Details The slide build highlights the key portions of the Timeline and source view. Questions to Ask Students Why do we call this a synchronization, and what is implicit about it? * Purpose of the Slide Refers students to the 6th lab activity, whose purpose is to run Parallel Amplifier analysis on the primes code. Details Detailed instructions are provided in the student lab manual. This lab exercise repeats the steps demonstrated in the preceding slides; students should expect to see similar results. * Purpose of the Slide To address the performance problem identified in the preceding slides and lab. Details The test, if (percentDone % 10 ==0), does NOT cause printi