Task03 Уткин Илья ITMO #107
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simiyutin
reviewed
Oct 5, 2024
| std::cout << "GPU sum_global_atomic: " << (n/1000.0/1000.0) / t.lapAvg() << " millions/s" << std::endl; | ||
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В этой и следующей версии один поток выполняет больше работы, сказывается ли это как-то на конфигурации рабочего пространства? (а конфигурация на производительности)
simiyutin
reviewed
Oct 5, 2024
| if (lid == 0) { | ||
| unsigned int group_res = 0; | ||
| for (unsigned int i = 0; i < get_local_size(0); i++) { |
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Есть ли здесь какое-то отличие между WORKGROUP SIZE и get_local_size?
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И если здесь в цикле написать константу времени компиляции то у меня локально кернел ускоряется в три раза (как общее правило по возможности в циклах кернелов стоит писать такие константы, например в виде дефайнов)
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Program build log:
Compilation started
Compilation done
Linking started
Linking done
Device build started
Device build done
Kernel <sum_global_atomic> was successfully vectorized (8)
Kernel <sum_cycle> was not vectorized
Kernel <sum_cycle_coalesce> was successfully vectorized (8)
Kernel <sum_local_mem> was successfully vectorized (8)
Kernel <sum_tree> was successfully vectorized (8)
Done.
Runtime:
Бейзлайн. Все операции суммирования стоят в очереди и драйвер никак не захотет это оптимизировать
GPU sum_global_atomic: 2.36046+-0.0251082 s
GPU sum_global_atomic: 42.3647 millions/s
Разбили работу на несколько групп и в разы сократили количество атомарных сложений. Получили существенный буст. Однако судя из билд лога у компиятора не получилось векторизовать эту операцию
GPU sum_cycle: 0.0818463+-0.001403 s
GPU sum_cycle: 1221.8 millions/s
Здесь уже получилось векторизовать кернел, получили еще буст.
GPU sum_cycle_coalesce: 0.0582893+-0.0026487 s
GPU sum_cycle_coalesce: 1715.58 millions/s
Пользуемся локальным кэшем. Удивлен что дало буст учитывая что запускаюсь на цпу. Видимо VRAM мапится в RAM а кэш гпу в кэш процесора.
GPU sum_local_mem: 0.0461117+-0.00118241 s
GPU sum_local_mem: 2168.65 millions/s
Дерево на ЦПУ дает не особо хороший буст по сравнению с бейзлайном.
GPU sum_tree: 0.162337+-0.00387873 s
GPU sum_tree: 616.001 millions/s