topology: BSD/MacOS fused + no libc dependency + sysctl auto ID / dyn…

…amic ID handling

constantine/threadpool/primitives/topology.nim

@@ -78,9 +78,7 @@
 
 import ../../zoo_exports
 
-when defined(ios) or defined(macosx):
-  import ./topology_macos
-elif defined(bsd):
+when defined(bsd) or defined(ios) or defined(macos) or defined(macosx):
   import ./topology_bsd
 elif defined(windows):
   # The following can handle Windows x86 and Windows ARM
@@ -122,9 +120,7 @@ proc getNumThreadsOS*(): cint {.libExport:"ctt_cpu_get_num_threads_os".} =
   ## For Simultaneous-Multithreading (SMT often call HyperThreading),
   ## this returns the number of available logical cores.
 
-  when defined(ios) or defined(macos) or defined(macosx):
-    queryAvailableThreadsMacOS()
-  elif defined(freebsd):
+  when defined(bsd) or defined(ios) or defined(macos) or defined(macosx):
     queryAvailableThreadsBSD()
   elif defined(windows):
     queryAvailableThreadsWindows()

constantine/threadpool/primitives/topology_bsd.nim

@@ -6,31 +6,74 @@
 #   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-proc c_printf(fmt: cstring): cint {.sideeffect, importc: "printf", header: "<stdio.h>", varargs, discardable, tags:[WriteIOEffect], noconv.}
-proc strerror(errnum: cint): cstring {.importc, header:"<string.h>", noconv.}
-proc sysctlbyname(name: cstring, oldp: pointer, oldlenp: ptr csize_t, newp: pointer, newlen: csize_t): int {.importc, header:"<sys/sysctl.h>", noconv.}
+# Kernel
+# ---------------------------------------------------
+# Many sysctl entries are given a dynamic ID (OID_AUTO)
+# like kern.smp.cores on FreeBSD: https://github.com/freebsd/freebsd-src/blob/release/14.0.0/sys/kern/subr_smp.c#L107-L109
+# or hw.physicalcpu_max on MacOS (no source)
+# while others are not available through sysctlbyname
+# like hw.availcpu on MacOS
+proc sysctl(mib: openArray[cint], oldp: pointer, oldlenp: var csize_t, newp: openArray[byte]): cint {.sideeffect, importc, header:"<sys/sysctl.h>", noconv.}
+proc sysctlbyname(name: cstring, oldp: pointer, oldlenp: var csize_t, newp: openArray[byte]): cint {.sideeffect, importc, header:"<sys/sysctl.h>", noconv.}
+
+template queryBsdKernel(arg: untyped): cint =
+  block:
+    var r: cint
+    var size = csize_t sizeof(r)
+    when arg is string:
+      const argDesc = arg
+      let ko = sysctlbyname(arg, r.addr, size, []) != 0
+    else:
+      const argDesc = astToStr(arg)
+      let ko = sysctl(arg, r.addr, size, []) != 0
+
+    if ko:
+      c_printf("[Constantine's Threadpool] sysctl(\"%s\") failure: %s\n", argDesc, strerror(errno))
+      r = -1
+    elif r <= 0:
+      c_printf("[Constantine's Threadpool] sysctl(\"%s\") invalid value: %d\n", argDesc, r)
+      r = -1
+    r
+
+# Error handling
+# ---------------------------------------------------
 
+proc c_printf(fmt: cstring): cint {.sideeffect, importc: "printf", header: "<stdio.h>", varargs, discardable, tags:[WriteIOEffect].}
+proc strerror(errnum: cint): cstring {.importc, header:"<string.h>", noconv.}
 var errno {.importc, header: "<errno.h>".}: cint
 
-proc queryNumPhysicalCoresFreeBSD*(): int32 {.inline.} =
-  var size = csize_t sizeof(result)
-  let ko = sysctlbyname("kern.smp.cores", result.addr, size.addr, nil, 0) != 0
-  if ko:
-    c_printf("[Constantine's Threadpool] sysctlbyname(\"kern.smp.cores\") failure: %s\n", strerror(errno))
-    result = -1
-  elif result <= 0:
-    c_printf("[Constantine's Threadpool] sysctlbyname(\"kern.smp.cores\") invalid value: %d\n", result)
-    result = -1
+# Topology queries
+# ---------------------------------------------------
+
+proc queryNumPhysicalCoresFreeBSD*(): cint {.inline.} =
+  queryBsdKernel"kern.smp.cores"
+
+proc queryNumPhysicalCoresMacOS*(): cint {.inline.} =
+  # Note:
+  # - hw.physicalcpu     is the number of cores available in current power management mode
+  # - hw.physicalcpu_max is the max number of cores available this boot.
+  # i.e. if we may start compute from low power mode with few CPUs "available".
+  queryBsdKernel"hw.physicalcpu_max"
 
 proc queryAvailableThreadsBSD*(): cint {.inline.} =
-  # TODO, avoid dependencies on libc
-  # - MacOS has HW_AVAILCPU
-  # - OpenBSD and NetBSD have HW_NCPUONLINE
-  #   https://github.com/openbsd/src/blob/master/lib/libc/gen/sysconf.c#L467-L470
-  #   https://github.com/NetBSD/src/blob/trunk/lib/libc/gen/sysconf.c#L372-L375
-  # - FreeBSD has no "online CPUs" facilities
-  #   and only provides HW_NCPUS
-  #   https://github.com/freebsd/freebsd-src/blob/release/14.0.0/lib/libc/gen/sysconf.c#L583-L589
-  let SC_NPROCESSORS_ONLN {.importc: "_SC_NPROCESSORS_ONLN", header: "<unistd.h>".}: cint
-  proc sysconf(name: cint): cint {.importc, header: "<unistd.h>", noconv.}
-  return sysconf(SC_NPROCESSORS_ONLN)
+  when defined(ios) or defined(macos) or defined(macosx):
+    let CTL_HW {.importc.}: cint
+    let HW_AVAILCPU {.importc.}: cint
+    queryBsdKernel([CTL_HW, HW_AVAILCPU])
+  elif defined(freebsd):
+    # For some reason, sysconf(SC_NPROCESSORS_ONLN) uses HW_NCPUS
+    # - https://github.com/freebsd/freebsd-src/blob/release/14.0.0/lib/libc/gen/sysconf.c#L583-L589
+    # instead of its builtin CPU online facility:
+    # - https://github.com/freebsd/freebsd-src/blob/release/14.0.0/sys/kern/subr_smp.c#L99-L101
+    queryBsdKernel"kern.smp.cpus"
+  elif defined(netbsd) or defined(openbsd):
+    # - OpenBSD and NetBSD have HW_NCPUONLINE
+    #   https://github.com/openbsd/src/blob/master/lib/libc/gen/sysconf.c#L467-L470
+    #   https://github.com/NetBSD/src/blob/trunk/lib/libc/gen/sysconf.c#L372-L375
+    let CTL_HW {.importc.}: cint
+    let HW_NCPUONLINE {.importc.}: cint
+    queryBsdKernel([CTL_HW, HW_NCPUONLINE])
+  else: # libc dependency and more recent BSDs
+    let SC_NPROCESSORS_ONLN {.importc: "_SC_NPROCESSORS_ONLN", header: "<unistd.h>".}: cint
+    proc sysconf(name: cint): cint {.importc, header: "<unistd.h>", noconv.}
+    return sysconf(SC_NPROCESSORS_ONLN)