1//===- Unix/Threading.inc - Unix Threading Implementation ----- -*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file provides the Unix specific implementation of Threading functions.
10//
11//===----------------------------------------------------------------------===//
12
13#include "Unix.h"
14#include "llvm/ADT/ScopeExit.h"
15#include "llvm/ADT/SmallString.h"
16#include "llvm/ADT/SmallVector.h"
17#include "llvm/ADT/StringRef.h"
18#include "llvm/ADT/Twine.h"
19#include "llvm/Support/MemoryBuffer.h"
20#include "llvm/Support/raw_ostream.h"
21
22#if defined(__APPLE__)
23#include <mach/mach_init.h>
24#include <mach/mach_port.h>
25#include <pthread/qos.h>
26#include <sys/sysctl.h>
27#include <sys/types.h>
28#endif
29
30#include <pthread.h>
31
32#if defined(__FreeBSD__) || defined(__OpenBSD__)
33#include <pthread_np.h> // For pthread_getthreadid_np() / pthread_set_name_np()
34#endif
35
36#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
37#include <errno.h>
38#include <sys/cpuset.h>
39#include <sys/sysctl.h>
40#include <sys/user.h>
41#include <unistd.h>
42#endif
43
44#if defined(__NetBSD__)
45#include <lwp.h> // For _lwp_self()
46#endif
47
48#if defined(__OpenBSD__)
49#include <unistd.h> // For getthrid()
50#endif
51
52#if defined(__linux__)
53#include <sched.h>       // For sched_getaffinity
54#include <sys/syscall.h> // For syscall codes
55#include <unistd.h>      // For syscall()
56#endif
57
58namespace llvm {
59pthread_t
60llvm_execute_on_thread_impl(void *(*ThreadFunc)(void *), void *Arg,
61                            std::optional<unsigned> StackSizeInBytes) {
62  int errnum;
63
64  // Construct the attributes object.
65  pthread_attr_t Attr;
66  if ((errnum = ::pthread_attr_init(&Attr)) != 0) {
67    ReportErrnumFatal("pthread_attr_init failed", errnum);
68  }
69
70  auto AttrGuard = llvm::make_scope_exit([&] {
71    if ((errnum = ::pthread_attr_destroy(&Attr)) != 0) {
72      ReportErrnumFatal("pthread_attr_destroy failed", errnum);
73    }
74  });
75
76  // Set the requested stack size, if given.
77  if (StackSizeInBytes) {
78    if ((errnum = ::pthread_attr_setstacksize(&Attr, *StackSizeInBytes)) != 0) {
79      ReportErrnumFatal("pthread_attr_setstacksize failed", errnum);
80    }
81  }
82
83  // Construct and execute the thread.
84  pthread_t Thread;
85  if ((errnum = ::pthread_create(&Thread, &Attr, ThreadFunc, Arg)) != 0)
86    ReportErrnumFatal("pthread_create failed", errnum);
87
88  return Thread;
89}
90
91void llvm_thread_detach_impl(pthread_t Thread) {
92  int errnum;
93
94  if ((errnum = ::pthread_detach(Thread)) != 0) {
95    ReportErrnumFatal("pthread_detach failed", errnum);
96  }
97}
98
99void llvm_thread_join_impl(pthread_t Thread) {
100  int errnum;
101
102  if ((errnum = ::pthread_join(Thread, nullptr)) != 0) {
103    ReportErrnumFatal("pthread_join failed", errnum);
104  }
105}
106
107pthread_t llvm_thread_get_id_impl(pthread_t Thread) { return Thread; }
108
109pthread_t llvm_thread_get_current_id_impl() { return ::pthread_self(); }
110
111} // namespace llvm
112
113uint64_t llvm::get_threadid() {
114#if defined(__APPLE__)
115  // Calling "mach_thread_self()" bumps the reference count on the thread
116  // port, so we need to deallocate it. mach_task_self() doesn't bump the ref
117  // count.
118  thread_port_t Self = mach_thread_self();
119  mach_port_deallocate(mach_task_self(), Self);
120  return Self;
121#elif defined(__FreeBSD__)
122  return uint64_t(pthread_getthreadid_np());
123#elif defined(__NetBSD__)
124  return uint64_t(_lwp_self());
125#elif defined(__OpenBSD__)
126  return uint64_t(getthrid());
127#elif defined(__ANDROID__)
128  return uint64_t(gettid());
129#elif defined(__linux__)
130  return uint64_t(syscall(SYS_gettid));
131#else
132  return uint64_t(pthread_self());
133#endif
134}
135
136static constexpr uint32_t get_max_thread_name_length_impl() {
137#if defined(__NetBSD__)
138  return PTHREAD_MAX_NAMELEN_NP;
139#elif defined(__APPLE__)
140  return 64;
141#elif defined(__linux__)
142#if HAVE_PTHREAD_SETNAME_NP
143  return 16;
144#else
145  return 0;
146#endif
147#elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
148  return 16;
149#elif defined(__OpenBSD__)
150  return 32;
151#else
152  return 0;
153#endif
154}
155
156uint32_t llvm::get_max_thread_name_length() {
157  return get_max_thread_name_length_impl();
158}
159
160void llvm::set_thread_name(const Twine &Name) {
161  // Make sure the input is null terminated.
162  SmallString<64> Storage;
163  StringRef NameStr = Name.toNullTerminatedStringRef(Storage);
164
165  // Truncate from the beginning, not the end, if the specified name is too
166  // long.  For one, this ensures that the resulting string is still null
167  // terminated, but additionally the end of a long thread name will usually
168  // be more unique than the beginning, since a common pattern is for similar
169  // threads to share a common prefix.
170  // Note that the name length includes the null terminator.
171  if (get_max_thread_name_length() > 0)
172    NameStr = NameStr.take_back(get_max_thread_name_length() - 1);
173  (void)NameStr;
174#if defined(__linux__)
175#if (defined(__GLIBC__) && defined(_GNU_SOURCE)) || defined(__ANDROID__)
176#if HAVE_PTHREAD_SETNAME_NP
177  ::pthread_setname_np(::pthread_self(), NameStr.data());
178#endif
179#endif
180#elif defined(__FreeBSD__) || defined(__OpenBSD__)
181  ::pthread_set_name_np(::pthread_self(), NameStr.data());
182#elif defined(__NetBSD__)
183  ::pthread_setname_np(::pthread_self(), "%s",
184                       const_cast<char *>(NameStr.data()));
185#elif defined(__APPLE__)
186  ::pthread_setname_np(NameStr.data());
187#endif
188}
189
190void llvm::get_thread_name(SmallVectorImpl<char> &Name) {
191  Name.clear();
192
193#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
194  int pid = ::getpid();
195  uint64_t tid = get_threadid();
196
197  struct kinfo_proc *kp = nullptr, *nkp;
198  size_t len = 0;
199  int error;
200  int ctl[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PID | KERN_PROC_INC_THREAD,
201                (int)pid};
202
203  while (1) {
204    error = sysctl(ctl, 4, kp, &len, nullptr, 0);
205    if (kp == nullptr || (error != 0 && errno == ENOMEM)) {
206      // Add extra space in case threads are added before next call.
207      len += sizeof(*kp) + len / 10;
208      nkp = (struct kinfo_proc *)::realloc(kp, len);
209      if (nkp == nullptr) {
210        free(kp);
211        return;
212      }
213      kp = nkp;
214      continue;
215    }
216    if (error != 0)
217      len = 0;
218    break;
219  }
220
221  for (size_t i = 0; i < len / sizeof(*kp); i++) {
222    if (kp[i].ki_tid == (lwpid_t)tid) {
223      Name.append(kp[i].ki_tdname, kp[i].ki_tdname + strlen(kp[i].ki_tdname));
224      break;
225    }
226  }
227  free(kp);
228  return;
229#elif defined(__NetBSD__)
230  constexpr uint32_t len = get_max_thread_name_length_impl();
231  char buf[len];
232  ::pthread_getname_np(::pthread_self(), buf, len);
233
234  Name.append(buf, buf + strlen(buf));
235#elif defined(__OpenBSD__)
236  constexpr uint32_t len = get_max_thread_name_length_impl();
237  char buf[len];
238  ::pthread_get_name_np(::pthread_self(), buf, len);
239
240  Name.append(buf, buf + strlen(buf));
241#elif defined(__linux__)
242#if HAVE_PTHREAD_GETNAME_NP
243  constexpr uint32_t len = get_max_thread_name_length_impl();
244  char Buffer[len] = {'\0'}; // FIXME: working around MSan false positive.
245  if (0 == ::pthread_getname_np(::pthread_self(), Buffer, len))
246    Name.append(Buffer, Buffer + strlen(Buffer));
247#endif
248#endif
249}
250
251SetThreadPriorityResult llvm::set_thread_priority(ThreadPriority Priority) {
252#if defined(__linux__) && defined(SCHED_IDLE)
253  // Some *really* old glibcs are missing SCHED_IDLE.
254  // http://man7.org/linux/man-pages/man3/pthread_setschedparam.3.html
255  // http://man7.org/linux/man-pages/man2/sched_setscheduler.2.html
256  sched_param priority;
257  // For each of the above policies, param->sched_priority must be 0.
258  priority.sched_priority = 0;
259  // SCHED_IDLE    for running very low priority background jobs.
260  // SCHED_OTHER   the standard round-robin time-sharing policy;
261  return !pthread_setschedparam(
262             pthread_self(),
263             // FIXME: consider SCHED_BATCH for Low
264             Priority == ThreadPriority::Default ? SCHED_OTHER : SCHED_IDLE,
265             &priority)
266             ? SetThreadPriorityResult::SUCCESS
267             : SetThreadPriorityResult::FAILURE;
268#elif defined(__APPLE__)
269  // https://developer.apple.com/documentation/apple-silicon/tuning-your-code-s-performance-for-apple-silicon
270  //
271  // Background - Applies to work that isn’t visible to the user and may take
272  // significant time to complete. Examples include indexing, backing up, or
273  // synchronizing data. This class emphasizes energy efficiency.
274  //
275  // Utility - Applies to work that takes anywhere from a few seconds to a few
276  // minutes to complete. Examples include downloading a document or importing
277  // data. This class offers a balance between responsiveness, performance, and
278  // energy efficiency.
279  const auto qosClass = [&]() {
280    switch (Priority) {
281    case ThreadPriority::Background:
282      return QOS_CLASS_BACKGROUND;
283    case ThreadPriority::Low:
284      return QOS_CLASS_UTILITY;
285    case ThreadPriority::Default:
286      return QOS_CLASS_DEFAULT;
287    }
288  }();
289  return !pthread_set_qos_class_self_np(qosClass, 0)
290             ? SetThreadPriorityResult::SUCCESS
291             : SetThreadPriorityResult::FAILURE;
292#endif
293  return SetThreadPriorityResult::FAILURE;
294}
295
296#include <thread>
297
298static int computeHostNumHardwareThreads() {
299#if defined(__FreeBSD__)
300  cpuset_t mask;
301  CPU_ZERO(&mask);
302  if (cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_TID, -1, sizeof(mask),
303                         &mask) == 0)
304    return CPU_COUNT(&mask);
305#elif defined(__linux__)
306  cpu_set_t Set;
307  if (sched_getaffinity(0, sizeof(Set), &Set) == 0)
308    return CPU_COUNT(&Set);
309#endif
310  // Guard against std::thread::hardware_concurrency() returning 0.
311  if (unsigned Val = std::thread::hardware_concurrency())
312    return Val;
313  return 1;
314}
315
316void llvm::ThreadPoolStrategy::apply_thread_strategy(
317    unsigned ThreadPoolNum) const {}
318
319llvm::BitVector llvm::get_thread_affinity_mask() {
320  // FIXME: Implement
321  llvm_unreachable("Not implemented!");
322}
323
324unsigned llvm::get_cpus() { return 1; }
325
326#if defined(__linux__) && (defined(__i386__) || defined(__x86_64__))
327// On Linux, the number of physical cores can be computed from /proc/cpuinfo,
328// using the number of unique physical/core id pairs. The following
329// implementation reads the /proc/cpuinfo format on an x86_64 system.
330static int computeHostNumPhysicalCores() {
331  // Enabled represents the number of physical id/core id pairs with at least
332  // one processor id enabled by the CPU affinity mask.
333  cpu_set_t Affinity, Enabled;
334  if (sched_getaffinity(0, sizeof(Affinity), &Affinity) != 0)
335    return -1;
336  CPU_ZERO(&Enabled);
337
338  // Read /proc/cpuinfo as a stream (until EOF reached). It cannot be
339  // mmapped because it appears to have 0 size.
340  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> Text =
341      llvm::MemoryBuffer::getFileAsStream("/proc/cpuinfo");
342  if (std::error_code EC = Text.getError()) {
343    llvm::errs() << "Can't read "
344                 << "/proc/cpuinfo: " << EC.message() << "\n";
345    return -1;
346  }
347  SmallVector<StringRef, 8> strs;
348  (*Text)->getBuffer().split(strs, "\n", /*MaxSplit=*/-1,
349                             /*KeepEmpty=*/false);
350  int CurProcessor = -1;
351  int CurPhysicalId = -1;
352  int CurSiblings = -1;
353  int CurCoreId = -1;
354  for (StringRef Line : strs) {
355    std::pair<StringRef, StringRef> Data = Line.split(':');
356    auto Name = Data.first.trim();
357    auto Val = Data.second.trim();
358    // These fields are available if the kernel is configured with CONFIG_SMP.
359    if (Name == "processor")
360      Val.getAsInteger(10, CurProcessor);
361    else if (Name == "physical id")
362      Val.getAsInteger(10, CurPhysicalId);
363    else if (Name == "siblings")
364      Val.getAsInteger(10, CurSiblings);
365    else if (Name == "core id") {
366      Val.getAsInteger(10, CurCoreId);
367      // The processor id corresponds to an index into cpu_set_t.
368      if (CPU_ISSET(CurProcessor, &Affinity))
369        CPU_SET(CurPhysicalId * CurSiblings + CurCoreId, &Enabled);
370    }
371  }
372  return CPU_COUNT(&Enabled);
373}
374#elif defined(__linux__) && defined(__s390x__)
375static int computeHostNumPhysicalCores() {
376  return sysconf(_SC_NPROCESSORS_ONLN);
377}
378#elif defined(__linux__) && !defined(__ANDROID__)
379static int computeHostNumPhysicalCores() {
380  cpu_set_t Affinity;
381  if (sched_getaffinity(0, sizeof(Affinity), &Affinity) == 0)
382    return CPU_COUNT(&Affinity);
383
384  // The call to sched_getaffinity() may have failed because the Affinity
385  // mask is too small for the number of CPU's on the system (i.e. the
386  // system has more than 1024 CPUs). Allocate a mask large enough for
387  // twice as many CPUs.
388  cpu_set_t *DynAffinity;
389  DynAffinity = CPU_ALLOC(2048);
390  if (sched_getaffinity(0, CPU_ALLOC_SIZE(2048), DynAffinity) == 0) {
391    int NumCPUs = CPU_COUNT(DynAffinity);
392    CPU_FREE(DynAffinity);
393    return NumCPUs;
394  }
395  return -1;
396}
397#elif defined(__APPLE__)
398// Gets the number of *physical cores* on the machine.
399static int computeHostNumPhysicalCores() {
400  uint32_t count;
401  size_t len = sizeof(count);
402  sysctlbyname("hw.physicalcpu", &count, &len, NULL, 0);
403  if (count < 1) {
404    int nm[2];
405    nm[0] = CTL_HW;
406    nm[1] = HW_AVAILCPU;
407    sysctl(nm, 2, &count, &len, NULL, 0);
408    if (count < 1)
409      return -1;
410  }
411  return count;
412}
413#elif defined(__MVS__)
414static int computeHostNumPhysicalCores() {
415  enum {
416    // Byte offset of the pointer to the Communications Vector Table (CVT) in
417    // the Prefixed Save Area (PSA). The table entry is a 31-bit pointer and
418    // will be zero-extended to uintptr_t.
419    FLCCVT = 16,
420    // Byte offset of the pointer to the Common System Data Area (CSD) in the
421    // CVT. The table entry is a 31-bit pointer and will be zero-extended to
422    // uintptr_t.
423    CVTCSD = 660,
424    // Byte offset to the number of live CPs in the LPAR, stored as a signed
425    // 32-bit value in the table.
426    CSD_NUMBER_ONLINE_STANDARD_CPS = 264,
427  };
428  char *PSA = 0;
429  char *CVT = reinterpret_cast<char *>(
430      static_cast<uintptr_t>(reinterpret_cast<unsigned int &>(PSA[FLCCVT])));
431  char *CSD = reinterpret_cast<char *>(
432      static_cast<uintptr_t>(reinterpret_cast<unsigned int &>(CVT[CVTCSD])));
433  return reinterpret_cast<int &>(CSD[CSD_NUMBER_ONLINE_STANDARD_CPS]);
434}
435#else
436// On other systems, return -1 to indicate unknown.
437static int computeHostNumPhysicalCores() { return -1; }
438#endif
439
440int llvm::get_physical_cores() {
441  static int NumCores = computeHostNumPhysicalCores();
442  return NumCores;
443}
444