bsd: use number of logical CPUs as automatic thread count

configure

@@ -1138,6 +1138,7 @@ HAVE_LIST="
     symver
     symver_asm_label
     symver_gnu_asm
+    sysctl
     sys_mman_h
     sys_resource_h
     sys_select_h
@@ -2856,6 +2857,7 @@ check_func  strerror_r
 check_func  strptime
 check_func  strtok_r
 check_func  sched_getaffinity
+check_func  sysctl
 check_func_headers io.h setmode
 check_func_headers lzo/lzo1x.h lzo1x_999_compress
 check_lib2 "windows.h psapi.h" GetProcessMemoryInfo -lpsapi

libavcodec/pthread.c

@@ -36,6 +36,9 @@
 #include <sched.h>
 #elif HAVE_GETSYSTEMINFO
 #include <windows.h>
+#elif HAVE_SYSCTL
+#include <sys/sysctl.h>
+#include <sys/types.h>
 #endif
 
 #include "avcodec.h"
@@ -162,6 +165,13 @@ static int get_logical_cpus(AVCodecContext *avctx)
     SYSTEM_INFO sysinfo;
     GetSystemInfo(&sysinfo);
     nb_cpus = sysinfo.dwNumberOfProcessors;
+#elif HAVE_SYSCTL
+    int mib[2] = { CTL_HW, HW_NCPU };
+    size_t len = sizeof(nb_cpus);
+
+    ret = sysctl(mib, 2, &nb_cpus, &len, NULL, 0);
+    if (ret == -1)
+        nb_cpus = 0;
 #endif
     av_log(avctx, AV_LOG_DEBUG, "detected %d logical cores\n", nb_cpus);
     return FFMIN(nb_cpus, MAX_AUTO_THREADS);