Line data    Source code

       1             : /* Copyright (c) 2003-2004, Roger Dingledine
       2             :  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
       3             :  * Copyright (c) 2007-2021, The Tor Project, Inc. */
       4             : /* See LICENSE for licensing information */
       5             : 
       6             : /**
       7             :  * \file numcpus.c
       8             :  * \brief Compute the number of CPUs configured on this system.
       9             :  **/
      10             : 
      11             : #include "orconfig.h"
      12             : #include "lib/thread/numcpus.h"
      13             : #include "lib/log/log.h"
      14             : #include "lib/log/util_bug.h"
      15             : 
      16             : #ifdef HAVE_UNISTD_H
      17             : #include <unistd.h>
      18             : #endif
      19             : #ifdef _WIN32
      20             : #include <windows.h>
      21             : #endif
      22             : 
      23             : #include <stdlib.h>
      24             : 
      25             : /** Implementation logic for compute_num_cpus(). */
      26             : static int
      27           5 : compute_num_cpus_impl(void)
      28             : {
      29             : #ifdef _WIN32
      30             :   SYSTEM_INFO info;
      31             :   memset(&info, 0, sizeof(info));
      32             :   GetSystemInfo(&info);
      33             :   if (info.dwNumberOfProcessors >= 1 && info.dwNumberOfProcessors < INT_MAX)
      34             :     return (int)info.dwNumberOfProcessors;
      35             :   else
      36             :     return -1;
      37             : #elif defined(HAVE_SYSCONF)
      38             : #ifdef _SC_NPROCESSORS_CONF
      39           5 :   long cpus_conf = sysconf(_SC_NPROCESSORS_CONF);
      40             : #else
      41             :   long cpus_conf = -1;
      42             : #endif
      43             : #ifdef _SC_NPROCESSORS_ONLN
      44           5 :   long cpus_onln = sysconf(_SC_NPROCESSORS_ONLN);
      45             : #else
      46             :   long cpus_onln = -1;
      47             : #endif
      48           5 :   long cpus = -1;
      49             : 
      50           5 :   if (cpus_conf > 0 && cpus_onln < 0) {
      51             :     cpus = cpus_conf;
      52           5 :   } else if (cpus_onln > 0 && cpus_conf < 0) {
      53             :     cpus = cpus_onln;
      54           5 :   } else if (cpus_onln > 0 && cpus_conf > 0) {
      55           5 :     if (cpus_onln < cpus_conf) {
      56           0 :       log_notice(LD_GENERAL, "I think we have %ld CPUS, but only %ld of them "
      57             :                  "are available. Telling Tor to only use %ld. You can over"
      58             :                  "ride this with the NumCPUs option",
      59             :                  cpus_conf, cpus_onln, cpus_onln);
      60             :     }
      61             :     cpus = cpus_onln;
      62             :   }
      63             : 
      64           5 :   if (cpus >= 1 && cpus < INT_MAX)
      65           5 :     return (int)cpus;
      66             :   else
      67             :     return -1;
      68             : #else
      69             :   return -1;
      70             : #endif /* defined(_WIN32) || ... */
      71             : }
      72             : 
      73             : #define MAX_DETECTABLE_CPUS 16
      74             : 
      75             : /** Return how many CPUs we are running with.  We assume that nobody is
      76             :  * using hot-swappable CPUs, so we don't recompute this after the first
      77             :  * time.  Return -1 if we don't know how to tell the number of CPUs on this
      78             :  * system.
      79             :  */
      80             : int
      81           5 : compute_num_cpus(void)
      82             : {
      83           5 :   static int num_cpus = -2;
      84           5 :   if (num_cpus == -2) {
      85           5 :     num_cpus = compute_num_cpus_impl();
      86           5 :     tor_assert(num_cpus != -2);
      87           5 :     if (num_cpus > MAX_DETECTABLE_CPUS) {
      88             :       /* LCOV_EXCL_START */
      89             :       log_notice(LD_GENERAL, "Wow!  I detected that you have %d CPUs. I "
      90             :                  "will not autodetect any more than %d, though.  If you "
      91             :                  "want to configure more, set NumCPUs in your torrc",
      92             :                  num_cpus, MAX_DETECTABLE_CPUS);
      93             :       num_cpus = MAX_DETECTABLE_CPUS;
      94             :       /* LCOV_EXCL_STOP */
      95             :     }
      96             :   }
      97           5 :   return num_cpus;
      98             : }