engines/cpu.c

   1 /*
   2  * CPU engine
   3  *
   4  * Doesn't transfer any data, merely burns CPU cycles according to
   5  * the settings.
   6  *
   7  */
   8 #include "../fio.h"
   9 #include "../optgroup.h"
  10
  11 struct cpu_options {
  12         void *pad;
  13         unsigned int cpuload;
  14         unsigned int cpucycle;
  15         unsigned int exit_io_done;
  16 };
  17
  18 static struct fio_option options[] = {
  19         {
  20                 .name   = "cpuload",
  21                 .lname  = "CPU load",
  22                 .type   = FIO_OPT_INT,
  23                 .off1   = offsetof(struct cpu_options, cpuload),
  24                 .help   = "Use this percentage of CPU",
  25                 .category = FIO_OPT_C_ENGINE,
  26                 .group  = FIO_OPT_G_INVALID,
  27         },
  28         {
  29                 .name   = "cpuchunks",
  30                 .lname  = "CPU chunk",
  31                 .type   = FIO_OPT_INT,
  32                 .off1   = offsetof(struct cpu_options, cpucycle),
  33                 .help   = "Length of the CPU burn cycles (usecs)",
  34                 .def    = "50000",
  35                 .parent = "cpuload",
  36                 .hide   = 1,
  37                 .category = FIO_OPT_C_ENGINE,
  38                 .group  = FIO_OPT_G_INVALID,
  39         },
  40         {
  41                 .name   = "exit_on_io_done",
  42                 .lname  = "Exit when IO threads are done",
  43                 .type   = FIO_OPT_BOOL,
  44                 .off1   = offsetof(struct cpu_options, exit_io_done),
  45                 .help   = "Exit when IO threads finish",
  46                 .def    = "0",
  47                 .category = FIO_OPT_C_ENGINE,
  48                 .group  = FIO_OPT_G_INVALID,
  49         },
  50         {
  51                 .name   = NULL,
  52         },
  53 };
  54
  55
  56 static enum fio_q_status fio_cpuio_queue(struct thread_data *td,
  57                                          struct io_u fio_unused *io_u)
  58 {
  59         struct cpu_options *co = td->eo;
  60
  61         if (co->exit_io_done && !fio_running_or_pending_io_threads()) {
  62                 td->done = 1;
  63                 return FIO_Q_BUSY;
  64         }
  65
  66         usec_spin(co->cpucycle);
  67         return FIO_Q_COMPLETED;
  68 }
  69
  70 static int fio_cpuio_init(struct thread_data *td)
  71 {
  72         struct thread_options *o = &td->o;
  73         struct cpu_options *co = td->eo;
  74
  75         if (!co->cpuload) {
  76                 td_vmsg(td, EINVAL, "cpu thread needs rate (cpuload=)","cpuio");
  77                 return 1;
  78         }
  79
  80         if (co->cpuload > 100)
  81                 co->cpuload = 100;
  82
  83         /*
  84          * set thinktime_sleep and thinktime_spin appropriately
  85          */
  86         o->thinktime_blocks = 1;
  87         o->thinktime_spin = 0;
  88         o->thinktime = ((unsigned long long) co->cpucycle * (100 - co->cpuload)) / co->cpuload;
  89
  90         o->nr_files = o->open_files = 1;
  91
  92         log_info("%s: ioengine=%s, cpuload=%u, cpucycle=%u\n",
  93                 td->o.name, td->io_ops->name, co->cpuload, co->cpucycle);
  94
  95         return 0;
  96 }
  97
  98 static int fio_cpuio_open(struct thread_data fio_unused *td,
  99                           struct fio_file fio_unused *f)
 100 {
 101         return 0;
 102 }
 103
 104 static struct ioengine_ops ioengine = {
 105         .name           = "cpuio",
 106         .version        = FIO_IOOPS_VERSION,
 107         .queue          = fio_cpuio_queue,
 108         .init           = fio_cpuio_init,
 109         .open_file      = fio_cpuio_open,
 110         .flags          = FIO_SYNCIO | FIO_DISKLESSIO | FIO_NOIO,
 111         .options                = options,
 112         .option_struct_size     = sizeof(struct cpu_options),
 113 };
 114
 115 static void fio_init fio_cpuio_register(void)
 116 {
 117         register_ioengine(&ioengine);
 118 }
 119
 120 static void fio_exit fio_cpuio_unregister(void)
 121 {
 122         unregister_ioengine(&ioengine);
 123 }