53 lines
2.0 KiB
Nim
53 lines
2.0 KiB
Nim
# Weave
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# Copyright (c) 2019 Mamy André-Ratsimbazafy
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# Licensed and distributed under either of
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# * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
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# * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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# Thread primitives
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# ----------------------------------------------------------------------------------
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type
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Pthread {.importc: "pthread_t", header: "<sys/types.h>".} = object
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CpuSet {.byref, importc: "cpu_set_t", header: "<sched.h>".} = object
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proc pthread_self(): Pthread {.header: "<pthread.h>".}
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proc pthread_setaffinity_np(
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thread: Pthread,
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cpuset_size: int,
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cpuset: CpuSet
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) {.header: "<pthread.h>".}
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## Limit specified `thread` to run only on the processors
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## represented in `cpuset`
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# Note CpuSet is always passed by (hidden) pointer
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proc cpu_zero(cpuset: var CpuSet) {.importc: "CPU_ZERO", header: "<sched.h>".}
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## Clears the set so that it contains no CPU
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proc cpu_set(cpu: cint, cpuset: var CpuSet) {.importc: "CPU_SET", header: "<sched.h>".}
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## Add CPU to set
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# Affinity
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# ----------------------------------------------------------------------------------
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# Nim doesn't allow the main thread to set its own affinity
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proc set_thread_affinity(t: Pthread, cpu: int32) {.inline.}=
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when defined(osx) or defined(android):
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{.warning: "To improve performance we should pin threads to cores.\n" &
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"This is not possible with MacOS or Android.".}
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# Note: on Android it's even more complex due to the Big.Little architecture
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# with cores with different performance profiles to save on battery
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else:
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var cpuset {.noinit.}: CpuSet
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cpu_zero(cpuset)
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cpu_set(cpu, cpuset)
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pthread_setaffinity_np(t, sizeof(CpuSet), cpuset)
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proc pinToCpu*(cpu: int32) {.inline.} =
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## Set the affinity of the main thread (the calling thread)
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set_thread_affinity(pthread_self(), cpu)
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