porting the feature for FreeBSD < 13.1 and testing the build on CI.

Above, it uses the same api as Linux.

Author: devnexen

configure.ac

@@ -406,6 +406,7 @@ strings.h \
 sched.h \
 syslog.h \
 sysexits.h \
+sys/cpuset.h \
 sys/ioctl.h \
 sys/file.h \
 sys/mman.h \
@@ -569,6 +570,7 @@ AC_CHECK_FUNCS(
 alphasort \
 asctime_r \
 chroot \
+cpuset_setaffinity \
 ctime_r \
 explicit_memset \
 fdatasync \

sapi/fpm/fpm/fpm_config.h

@@ -76,7 +76,7 @@
 # define HAVE_FPM_LQ 0
 #endif
 
-#if defined(HAVE_SCHED_SETAFFINITY)
+#if defined(HAVE_SCHED_SETAFFINITY) || defined(HAVE_CPUSET_SETAFFINITY)
 /*
  * to expand to other platforms capable of this granularity (some BSD, solaris, ...).
  * macOS is a specific case with an api working fine on intel architecture

sapi/fpm/fpm/fpm_unix.c

@@ -39,6 +39,11 @@
 #include <sched.h>
 #endif
 
+#ifdef HAVE_SYS_CPUSET_H
+#include <sys/cpuset.h>
+typedef cpuset_t cpu_set_t;
+#endif
+
 #include "fpm.h"
 #include "fpm_conf.h"
 #include "fpm_cleanup.h"
@@ -393,7 +398,7 @@ static int fpm_cpusrange(char *cpumask, int *min, int *max) {
 
 static int fpm_setcpuaffinity(int min, int max)
 {
-#ifdef HAVE_SCHED_SETAFFINITY
+#if defined(HAVE_SCHED_SETAFFINITY) || defined(HAVE_CPUSET_SETAFFINITY)
 	cpu_set_t cset;
 	int i;
 
@@ -404,7 +409,11 @@ static int fpm_setcpuaffinity(int min, int max)
 		}
 	}
 
+#if defined(HAVE_SCHED_SETAFFINITY)
 	return sched_setaffinity(0, sizeof(cset), &cset);
+#else
+	return cpuset_setaffinity(CPU_LEVEL_WHICH, CPU_WHICH_PID, -1, sizeof(cset), &cset);
+#endif
 #endif
 }
 #endif