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path: root/t/helper/test-lazy-init-name-hash.c
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2017-03-24name-hash: add test-lazy-init-name-hashLibravatar Jeff Hostetler1-0/+264
Add t/helper/test-lazy-init-name-hash.c test code to demonstrate performance times for lazy_init_name_hash() using the original single-threaded and the new multi-threaded code paths. Includes a --dump option to dump the created hashmaps to stdout. You can use this to run both code paths and confirm that they generate the same hashmaps. Includes a --analyze option to analyze performance of both code paths over a range of index sizes to help you find a lower bound for the LAZY_THREAD_COST in name-hash.c. For example, passing "-a 4000" will set "istate.cache_nr" to 4000 and then try the multi-threaded code -- probably giving 2 threads with 2000 entries each. It will then run both the single-threaded (1x4000) and the multi-threaded (2x2000) and compare the times. It will then repeat the test with 8000, 12000, and etc. so that you can see the cross over. Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>