diff --git a/gettime.c b/gettime.c
index 8993be1688..bc66a3ac9f 100644
--- a/gettime.c
+++ b/gettime.c
@@ -671,7 +671,7 @@ static int clock_cmp(const void *p1, const void *p2)
 int fio_monotonic_clocktest(int debug)
 {
 	struct clock_thread *cthreads;
-	unsigned int seen_cpus, nr_cpus = cpus_online();
+	unsigned int seen_cpus, nr_cpus = cpus_configured();
 	struct clock_entry *entries;
 	unsigned long nr_entries, tentries, failed = 0;
 	struct clock_entry *prev, *this;
diff --git a/idletime.c b/idletime.c
index fc1df8e9d0..90ed77ea6e 100644
--- a/idletime.c
+++ b/idletime.c
@@ -189,7 +189,7 @@ void fio_idle_prof_init(void)
 	pthread_condattr_t cattr;
 	struct idle_prof_thread *ipt;
 
-	ipc.nr_cpus = cpus_online();
+	ipc.nr_cpus = cpus_configured();
 	ipc.status = IDLE_PROF_STATUS_OK;
 
 	if (ipc.opt == IDLE_PROF_OPT_NONE)
diff --git a/options.c b/options.c
index a668b0e475..9e4d8cd1a9 100644
--- a/options.c
+++ b/options.c
@@ -627,7 +627,7 @@ static int str_exitall_cb(void)
 int fio_cpus_split(os_cpu_mask_t *mask, unsigned int cpu_index)
 {
 	unsigned int i, index, cpus_in_mask;
-	const long max_cpu = cpus_online();
+	const long max_cpu = cpus_configured();
 
 	cpus_in_mask = fio_cpu_count(mask);
 	if (!cpus_in_mask)
@@ -666,7 +666,7 @@ static int str_cpumask_cb(void *data, unsigned long long *val)
 		return 1;
 	}
 
-	max_cpu = cpus_online();
+	max_cpu = cpus_configured();
 
 	for (i = 0; i < sizeof(int) * 8; i++) {
 		if ((1 << i) & *val) {
@@ -702,7 +702,7 @@ static int set_cpus_allowed(struct thread_data *td, os_cpu_mask_t *mask,
 	strip_blank_front(&str);
 	strip_blank_end(str);
 
-	max_cpu = cpus_online();
+	max_cpu = cpus_configured();
 
 	while ((cpu = strsep(&str, ",")) != NULL) {
 		char *str2, *cpu2;
@@ -5305,7 +5305,7 @@ void fio_keywords_init(void)
 	sprintf(buf, "%llu", mb_memory);
 	fio_keywords[1].replace = strdup(buf);
 
-	l = cpus_online();
+	l = cpus_configured();
 	sprintf(buf, "%lu", l);
 	fio_keywords[2].replace = strdup(buf);
 }
diff --git a/os/os-hpux.h b/os/os-hpux.h
index a80cb2bc47..9f3d76f507 100644
--- a/os/os-hpux.h
+++ b/os/os-hpux.h
@@ -88,9 +88,9 @@ static inline unsigned long long os_phys_mem(void)
 	return ret;
 }
 
-#define FIO_HAVE_CPU_ONLINE_SYSCONF
+#define FIO_HAVE_CPU_CONF_SYSCONF
 
-static inline unsigned int cpus_online(void)
+static inline unsigned int cpus_configured(void)
 {
 	return mpctl(MPC_GETNUMSPUS, 0, NULL);
 }
diff --git a/os/os-linux.h b/os/os-linux.h
index 831f0ad047..bbb1f27c82 100644
--- a/os/os-linux.h
+++ b/os/os-linux.h
@@ -251,14 +251,6 @@ static inline int arch_cache_line_size(void)
 		return atoi(size);
 }
 
-#ifdef __powerpc64__
-#define FIO_HAVE_CPU_ONLINE_SYSCONF
-static inline unsigned int cpus_online(void)
-{
-        return sysconf(_SC_NPROCESSORS_CONF);
-}
-#endif
-
 static inline unsigned long long get_fs_free_size(const char *path)
 {
 	unsigned long long ret;
diff --git a/os/os-solaris.h b/os/os-solaris.h
index ea1f081c89..60d4c1eca4 100644
--- a/os/os-solaris.h
+++ b/os/os-solaris.h
@@ -119,7 +119,7 @@ static inline int fio_set_odirect(struct fio_file *f)
 
 static inline bool fio_cpu_isset(os_cpu_mask_t *mask, int cpu)
 {
-	const unsigned int max_cpus = sysconf(_SC_NPROCESSORS_ONLN);
+	const unsigned int max_cpus = sysconf(_SC_NPROCESSORS_CONF);
 	unsigned int num_cpus;
 	processorid_t *cpus;
 	bool ret;
diff --git a/os/os-windows.h b/os/os-windows.h
index 510b8143db..12f3348611 100644
--- a/os/os-windows.h
+++ b/os/os-windows.h
@@ -44,7 +44,7 @@
 #define fio_swap64(x)	_byteswap_uint64(x)
 
 #define _SC_PAGESIZE			0x1
-#define _SC_NPROCESSORS_ONLN	0x2
+#define _SC_NPROCESSORS_CONF	0x2
 #define _SC_PHYS_PAGES			0x4
 
 #define SA_RESTART	0
@@ -219,9 +219,6 @@ static inline int fio_mkdir(const char *path, mode_t mode) {
 	return 0;
 }
 
-#define FIO_HAVE_CPU_ONLINE_SYSCONF
-unsigned int cpus_online(void);
-
 int first_set_cpu(os_cpu_mask_t *cpumask);
 int fio_setaffinity(int pid, os_cpu_mask_t cpumask);
 int fio_cpuset_init(os_cpu_mask_t *mask);
diff --git a/os/os.h b/os/os.h
index aba6813f23..a6fde1fd27 100644
--- a/os/os.h
+++ b/os/os.h
@@ -352,10 +352,10 @@ static inline unsigned long long get_fs_free_size(const char *path)
 }
 #endif
 
-#ifndef FIO_HAVE_CPU_ONLINE_SYSCONF
-static inline unsigned int cpus_online(void)
+#ifndef FIO_HAVE_CPU_CONF_SYSCONF
+static inline unsigned int cpus_configured(void)
 {
-	return sysconf(_SC_NPROCESSORS_ONLN);
+	return sysconf(_SC_NPROCESSORS_CONF);
 }
 #endif
 
@@ -363,7 +363,7 @@ static inline unsigned int cpus_online(void)
 #ifdef FIO_HAVE_CPU_AFFINITY
 static inline int CPU_COUNT(os_cpu_mask_t *mask)
 {
-	int max_cpus = cpus_online();
+	int max_cpus = cpus_configured();
 	int nr_cpus, i;
 
 	for (i = 0, nr_cpus = 0; i < max_cpus; i++)
diff --git a/os/windows/cpu-affinity.c b/os/windows/cpu-affinity.c
index 7601970fc7..8f3d6a76b4 100644
--- a/os/windows/cpu-affinity.c
+++ b/os/windows/cpu-affinity.c
@@ -2,12 +2,6 @@
 
 #include <windows.h>
 
-/* Return all processors regardless of processor group */
-unsigned int cpus_online(void)
-{
-	return GetActiveProcessorCount(ALL_PROCESSOR_GROUPS);
-}
-
 static void print_mask(os_cpu_mask_t *cpumask)
 {
 	for (int i = 0; i < FIO_CPU_MASK_ROWS; i++)
diff --git a/os/windows/posix.c b/os/windows/posix.c
index a3a6c89fd0..a47223daaf 100644
--- a/os/windows/posix.c
+++ b/os/windows/posix.c
@@ -216,10 +216,18 @@ long sysconf(int name)
 	MEMORYSTATUSEX status;
 
 	switch (name) {
-	case _SC_NPROCESSORS_ONLN:
-		val = GetNumLogicalProcessors();
+	case _SC_NPROCESSORS_CONF:
+		/*
+		 * Using GetMaximumProcessorCount introduces a problem in
+		 * gettime.c because Windows does not have
+		 * fio_get_thread_affinity. Log sample (see #1479):
+		 *
+		 *   CPU mask contains processor beyond last active processor index (2)
+		 *   clock setaffinity failed: No error
+		 */
+		val = GetActiveProcessorCount(ALL_PROCESSOR_GROUPS);
 		if (val == -1)
-			log_err("sysconf(_SC_NPROCESSORS_ONLN) failed\n");
+			log_err("sysconf(_SC_NPROCESSORS_CONF) failed\n");
 
 		break;
 
@@ -1201,4 +1209,4 @@ HANDLE windows_handle_connection(HANDLE hjob, int sk)
 	DisconnectNamedPipe(hpipe);
 	CloseHandle(hpipe);
 	return ret;
-}
\ No newline at end of file
+}
diff --git a/server.c b/server.c
index b453be5fc3..b869d38727 100644
--- a/server.c
+++ b/server.c
@@ -999,7 +999,7 @@ static int handle_probe_cmd(struct fio_net_cmd *cmd)
 		.os		= FIO_OS,
 		.arch		= FIO_ARCH,
 		.bpp		= sizeof(void *),
-		.cpus		= __cpu_to_le32(cpus_online()),
+		.cpus		= __cpu_to_le32(cpus_configured()),
 	};
 
 	dprint(FD_NET, "server: sending probe reply\n");
diff --git a/t/dedupe.c b/t/dedupe.c
index d21e96f4d9..02e52b742e 100644
--- a/t/dedupe.c
+++ b/t/dedupe.c
@@ -688,7 +688,7 @@ int main(int argc, char *argv[])
 		use_bloom = 0;
 
 	if (!num_threads)
-		num_threads = cpus_online();
+		num_threads = cpus_configured();
 
 	if (argc == optind)
 		return usage(argv);