1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
//! A crate with utilities to determine the number of CPUs available on the
//! current system.
//!
//! Sometimes the CPU will exaggerate the number of CPUs it contains, because it can use
//! [processor tricks] to deliver increased performance when there are more threads. This
//! crate provides methods to get both the logical and physical numbers of cores.
//!
//! This information can be used as a guide to how many tasks can be run in parallel.
//! There are many properties of the system architecture that will affect parallelism,
//! for example memory access speeds (for all the caches and RAM) and the physical
//! architecture of the processor, so the number of CPUs should be used as a rough guide
//! only.
//!
//!
//! ## Examples
//!
//! Fetch the number of logical CPUs.
//!
//! ```
//! let cpus = num_cpus::get();
//! ```
//!
//! See [`rayon::Threadpool`] for an example of where the number of CPUs could be
//! used when setting up parallel jobs (Where the threadpool example uses a fixed
//! number 8, it could use the number of CPUs).
//!
//! [processor tricks]: https://en.wikipedia.org/wiki/Simultaneous_multithreading
//! [`rayon::ThreadPool`]: https://docs.rs/rayon/1.*/rayon/struct.ThreadPool.html
#![cfg_attr(test, deny(warnings))]
#![deny(missing_docs)]
#![allow(non_snake_case)]

#[cfg(not(windows))]
extern crate libc;

#[cfg(target_os = "hermit")]
extern crate hermit_abi;

#[cfg(all(target_os = "linux", not(target_vendor = "teaclave")))]
mod linux;
#[cfg(all(target_os = "linux", not(target_vendor = "teaclave")))]
use linux::{get_num_cpus, get_num_physical_cpus};

#[cfg(target_vendor = "teaclave")]
mod sgx;
#[cfg(target_vendor = "teaclave")]
use sgx::{get_num_cpus, get_num_physical_cpus};
/// Returns the number of available CPUs of the current system.
///
/// This function will get the number of logical cores. Sometimes this is different from the number
/// of physical cores (See [Simultaneous multithreading on Wikipedia][smt]).
///
/// This will always return at least `1`.
///
/// # Examples
///
/// ```
/// let cpus = num_cpus::get();
/// if cpus > 1 {
///     println!("We are on a multicore system with {} CPUs", cpus);
/// } else {
///     println!("We are on a single core system");
/// }
/// ```
///
/// # Note
///
/// This will check [sched affinity] on Linux, showing a lower number of CPUs if the current
/// thread does not have access to all the computer's CPUs.
///
/// This will also check [cgroups], frequently used in containers to constrain CPU usage.
///
/// [smt]: https://en.wikipedia.org/wiki/Simultaneous_multithreading
/// [sched affinity]: http://www.gnu.org/software/libc/manual/html_node/CPU-Affinity.html
/// [cgroups]: https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt
#[inline]
pub fn get() -> usize {
    get_num_cpus()
}

/// Returns the number of physical cores of the current system.
///
/// This will always return at least `1`.
///
/// # Note
///
/// Physical count is supported only on Linux, mac OS and Windows platforms.
/// On other platforms, or if the physical count fails on supported platforms,
/// this function returns the same as [`get()`], which is the number of logical
/// CPUS.
///
/// # Examples
///
/// ```
/// let logical_cpus = num_cpus::get();
/// let physical_cpus = num_cpus::get_physical();
/// if logical_cpus > physical_cpus {
///     println!("We have simultaneous multithreading with about {:.2} \
///               logical cores to 1 physical core.",
///               (logical_cpus as f64) / (physical_cpus as f64));
/// } else if logical_cpus == physical_cpus {
///     println!("Either we don't have simultaneous multithreading, or our \
///               system doesn't support getting the number of physical CPUs.");
/// } else {
///     println!("We have less logical CPUs than physical CPUs, maybe we only have access to \
///               some of the CPUs on our system.");
/// }
/// ```
///
/// [`get()`]: fn.get.html
#[inline]
pub fn get_physical() -> usize {
    get_num_physical_cpus()
}

#[cfg(not(any(
    target_os = "linux",
    target_os = "windows",
    target_os = "macos",
    target_os = "openbsd"
)))]
#[inline]
fn get_num_physical_cpus() -> usize {
    // Not implemented, fall back
    get_num_cpus()
}

#[cfg(target_os = "windows")]
fn get_num_physical_cpus() -> usize {
    match get_num_physical_cpus_windows() {
        Some(num) => num,
        None => get_num_cpus(),
    }
}

#[cfg(target_os = "windows")]
fn get_num_physical_cpus_windows() -> Option<usize> {
    // Inspired by https://msdn.microsoft.com/en-us/library/ms683194

    use std::mem;
    use std::ptr;

    #[allow(non_upper_case_globals)]
    const RelationProcessorCore: u32 = 0;

    #[repr(C)]
    #[allow(non_camel_case_types)]
    struct SYSTEM_LOGICAL_PROCESSOR_INFORMATION {
        mask: usize,
        relationship: u32,
        _unused: [u64; 2],
    }

    extern "system" {
        fn GetLogicalProcessorInformation(
            info: *mut SYSTEM_LOGICAL_PROCESSOR_INFORMATION,
            length: &mut u32,
        ) -> u32;
    }

    // First we need to determine how much space to reserve.

    // The required size of the buffer, in bytes.
    let mut needed_size = 0;

    unsafe {
        GetLogicalProcessorInformation(ptr::null_mut(), &mut needed_size);
    }

    let struct_size = mem::size_of::<SYSTEM_LOGICAL_PROCESSOR_INFORMATION>() as u32;

    // Could be 0, or some other bogus size.
    if needed_size == 0 || needed_size < struct_size || needed_size % struct_size != 0 {
        return None;
    }

    let count = needed_size / struct_size;

    // Allocate some memory where we will store the processor info.
    let mut buf = Vec::with_capacity(count as usize);

    let result;

    unsafe {
        result = GetLogicalProcessorInformation(buf.as_mut_ptr(), &mut needed_size);
    }

    // Failed for any reason.
    if result == 0 {
        return None;
    }

    let count = needed_size / struct_size;

    unsafe {
        buf.set_len(count as usize);
    }

    let phys_proc_count = buf
        .iter()
        // Only interested in processor packages (physical processors.)
        .filter(|proc_info| proc_info.relationship == RelationProcessorCore)
        .count();

    if phys_proc_count == 0 {
        None
    } else {
        Some(phys_proc_count)
    }
}

#[cfg(windows)]
fn get_num_cpus() -> usize {
    #[repr(C)]
    struct SYSTEM_INFO {
        wProcessorArchitecture: u16,
        wReserved: u16,
        dwPageSize: u32,
        lpMinimumApplicationAddress: *mut u8,
        lpMaximumApplicationAddress: *mut u8,
        dwActiveProcessorMask: *mut u8,
        dwNumberOfProcessors: u32,
        dwProcessorType: u32,
        dwAllocationGranularity: u32,
        wProcessorLevel: u16,
        wProcessorRevision: u16,
    }

    extern "system" {
        fn GetSystemInfo(lpSystemInfo: *mut SYSTEM_INFO);
    }

    unsafe {
        let mut sysinfo: SYSTEM_INFO = std::mem::zeroed();
        GetSystemInfo(&mut sysinfo);
        sysinfo.dwNumberOfProcessors as usize
    }
}

#[cfg(any(target_os = "freebsd", target_os = "dragonfly", target_os = "netbsd"))]
fn get_num_cpus() -> usize {
    use std::ptr;

    let mut cpus: libc::c_uint = 0;
    let mut cpus_size = std::mem::size_of_val(&cpus);

    unsafe {
        cpus = libc::sysconf(libc::_SC_NPROCESSORS_ONLN) as libc::c_uint;
    }
    if cpus < 1 {
        let mut mib = [libc::CTL_HW, libc::HW_NCPU, 0, 0];
        unsafe {
            libc::sysctl(
                mib.as_mut_ptr(),
                2,
                &mut cpus as *mut _ as *mut _,
                &mut cpus_size as *mut _ as *mut _,
                ptr::null_mut(),
                0,
            );
        }
        if cpus < 1 {
            cpus = 1;
        }
    }
    cpus as usize
}

#[cfg(target_os = "openbsd")]
fn get_num_cpus() -> usize {
    use std::ptr;

    let mut cpus: libc::c_uint = 0;
    let mut cpus_size = std::mem::size_of_val(&cpus);
    let mut mib = [libc::CTL_HW, libc::HW_NCPUONLINE, 0, 0];
    let rc: libc::c_int;

    unsafe {
        rc = libc::sysctl(
            mib.as_mut_ptr(),
            2,
            &mut cpus as *mut _ as *mut _,
            &mut cpus_size as *mut _ as *mut _,
            ptr::null_mut(),
            0,
        );
    }
    if rc < 0 {
        cpus = 1;
    }
    cpus as usize
}

#[cfg(target_os = "openbsd")]
fn get_num_physical_cpus() -> usize {
    use std::ptr;

    let mut cpus: libc::c_uint = 0;
    let mut cpus_size = std::mem::size_of_val(&cpus);
    let mut mib = [libc::CTL_HW, libc::HW_NCPU, 0, 0];
    let rc: libc::c_int;

    unsafe {
        rc = libc::sysctl(
            mib.as_mut_ptr(),
            2,
            &mut cpus as *mut _ as *mut _,
            &mut cpus_size as *mut _ as *mut _,
            ptr::null_mut(),
            0,
        );
    }
    if rc < 0 {
        cpus = 1;
    }
    cpus as usize
}

#[cfg(target_os = "macos")]
fn get_num_physical_cpus() -> usize {
    use std::ffi::CStr;
    use std::ptr;

    let mut cpus: i32 = 0;
    let mut cpus_size = std::mem::size_of_val(&cpus);

    let sysctl_name =
        CStr::from_bytes_with_nul(b"hw.physicalcpu\0").expect("byte literal is missing NUL");

    unsafe {
        if 0 != libc::sysctlbyname(
            sysctl_name.as_ptr(),
            &mut cpus as *mut _ as *mut _,
            &mut cpus_size as *mut _ as *mut _,
            ptr::null_mut(),
            0,
        ) {
            return get_num_cpus();
        }
    }
    cpus as usize
}

#[cfg(any(
    target_os = "nacl",
    target_os = "macos",
    target_os = "ios",
    target_os = "android",
    target_os = "solaris",
    target_os = "illumos",
    target_os = "fuchsia"
))]
fn get_num_cpus() -> usize {
    // On ARM targets, processors could be turned off to save power.
    // Use `_SC_NPROCESSORS_CONF` to get the real number.
    #[cfg(any(target_arch = "arm", target_arch = "aarch64"))]
    const CONF_NAME: libc::c_int = libc::_SC_NPROCESSORS_CONF;
    #[cfg(not(any(target_arch = "arm", target_arch = "aarch64")))]
    const CONF_NAME: libc::c_int = libc::_SC_NPROCESSORS_ONLN;

    let cpus = unsafe { libc::sysconf(CONF_NAME) };
    if cpus < 1 {
        1
    } else {
        cpus as usize
    }
}

#[cfg(target_os = "haiku")]
fn get_num_cpus() -> usize {
    use std::mem;

    #[allow(non_camel_case_types)]
    type bigtime_t = i64;
    #[allow(non_camel_case_types)]
    type status_t = i32;

    #[repr(C)]
    pub struct system_info {
        pub boot_time: bigtime_t,
        pub cpu_count: u32,
        pub max_pages: u64,
        pub used_pages: u64,
        pub cached_pages: u64,
        pub block_cache_pages: u64,
        pub ignored_pages: u64,
        pub needed_memory: u64,
        pub free_memory: u64,
        pub max_swap_pages: u64,
        pub free_swap_pages: u64,
        pub page_faults: u32,
        pub max_sems: u32,
        pub used_sems: u32,
        pub max_ports: u32,
        pub used_ports: u32,
        pub max_threads: u32,
        pub used_threads: u32,
        pub max_teams: u32,
        pub used_teams: u32,
        pub kernel_name: [::std::os::raw::c_char; 256usize],
        pub kernel_build_date: [::std::os::raw::c_char; 32usize],
        pub kernel_build_time: [::std::os::raw::c_char; 32usize],
        pub kernel_version: i64,
        pub abi: u32,
    }

    extern "C" {
        fn get_system_info(info: *mut system_info) -> status_t;
    }

    let mut info: system_info = unsafe { mem::zeroed() };
    let status = unsafe { get_system_info(&mut info as *mut _) };
    if status == 0 {
        info.cpu_count as usize
    } else {
        1
    }
}

#[cfg(target_os = "hermit")]
fn get_num_cpus() -> usize {
    unsafe { hermit_abi::get_processor_count() }
}

#[cfg(not(any(
    target_os = "nacl",
    target_os = "macos",
    target_os = "ios",
    target_os = "android",
    target_os = "solaris",
    target_os = "illumos",
    target_os = "fuchsia",
    target_os = "linux",
    target_os = "openbsd",
    target_os = "freebsd",
    target_os = "dragonfly",
    target_os = "netbsd",
    target_os = "haiku",
    target_os = "hermit",
    windows,
)))]
fn get_num_cpus() -> usize {
    1
}

#[cfg(test)]
mod tests {
    fn env_var(name: &'static str) -> Option<usize> {
        ::std::env::var(name).ok().map(|val| val.parse().unwrap())
    }

    #[test]
    fn test_get() {
        let num = super::get();
        if let Some(n) = env_var("NUM_CPUS_TEST_GET") {
            assert_eq!(num, n);
        } else {
            assert!(num > 0);
            assert!(num < 236_451);
        }
    }

    #[test]
    fn test_get_physical() {
        let num = super::get_physical();
        if let Some(n) = env_var("NUM_CPUS_TEST_GET_PHYSICAL") {
            assert_eq!(num, n);
        } else {
            assert!(num > 0);
            assert!(num < 236_451);
        }
    }
}