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and scheduler lock (pipe based or futex based) See http://www.valgrind.org/docs/manual/manual-core.html#manual-core.pthreads_perf_sched for background info about cpu freq scaling and valgrind thread scheduler. To reproduce the interaction, do: for sched in --fair-sched=yes --fair-sched=no do for affinity in 0 1 do echo $sched $affinity time ./vg-in-place $sched -q ./gdbserver_tests/sleepers 1000000 0 1000 B-B-B-B- $affinity done done which gives the below output (intel core i5-6402P, debian 8, kernel 3.16.0). In summary: the fair scheduler is fair, the pipe based scheduler can be really unfair (e.g. with --fair-sched=no and no affinity, 2 threads are finishing their work, while the 2 other threads are starting their work only after the first 2 have fully finished). The difference in timing is significant : 1m14s versus around 47 seconds. Note: If the governor is set to performance, strangely, the time needed for --fair-sched=no increases slighltly (to around 48 seconds). The time for --fair-sched=yes with or without affinity is then also to around 48 seconds. Below is timing with on-demand governor: --fair-sched=yes 0 loops/sleep_ms/burn/threads_spec/affinity: 1000000 0 1000 B-B-B-B- 0 Brussels ready to sleep and/or burn London ready to sleep and/or burn Petaouchnok ready to sleep and/or burn main ready to sleep and/or burn Brussels finished to sleep and/or burn London finished to sleep and/or burn Petaouchnok finished to sleep and/or burn main finished to sleep and/or burn real 1m14.582s user 1m14.348s sys 0m0.204s --fair-sched=yes 1 loops/sleep_ms/burn/threads_spec/affinity: 1000000 0 1000 B-B-B-B- 1 Brussels ready to sleep and/or burn London ready to sleep and/or burn Petaouchnok ready to sleep and/or burn main ready to sleep and/or burn main finished to sleep and/or burn Brussels finished to sleep and/or burn Petaouchnok finished to sleep and/or burn London finished to sleep and/or burn real 0m46.785s user 0m46.756s sys 0m0.032s --fair-sched=no 0 loops/sleep_ms/burn/threads_spec/affinity: 1000000 0 1000 B-B-B-B- 0 Brussels ready to sleep and/or burn Brussels finished to sleep and/or burn London ready to sleep and/or burn London finished to sleep and/or burn Petaouchnok ready to sleep and/or burn main ready to sleep and/or burn Petaouchnok finished to sleep and/or burn main finished to sleep and/or burn real 0m47.742s user 0m48.224s sys 0m0.084s --fair-sched=no 1 loops/sleep_ms/burn/threads_spec/affinity: 1000000 0 1000 B-B-B-B- 1 Brussels ready to sleep and/or burn London ready to sleep and/or burn Petaouchnok ready to sleep and/or burn main ready to sleep and/or burn Brussels finished to sleep and/or burn London finished to sleep and/or burn main finished to sleep and/or burn Petaouchnok finished to sleep and/or burn real 0m46.601s user 0m46.568s sys 0m0.036s git-svn-id: svn://svn.valgrind.org/valgrind/trunk@16251
12 lines
325 B
Plaintext
12 lines
325 B
Plaintext
Nulgrind, the minimal Valgrind tool
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(action at startup) vgdb me ...
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loops/sleep_ms/burn/threads_spec/affinity: 1000000000 1000000000 1 BSBSBSBS 1
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Brussels ready to sleep and/or burn
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London ready to sleep and/or burn
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Petaouchnok ready to sleep and/or burn
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main ready to sleep and/or burn
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Gdb request to kill this process
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