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      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 int fio_cpuio_queue(struct thread_data *td, struct io_u fio_unused *io_u)
     57 {
     58 	struct cpu_options *co = td->eo;
     59 
     60 	if (co->exit_io_done && !fio_running_or_pending_io_threads()) {
     61 		td->done = 1;
     62 		return FIO_Q_BUSY;
     63 	}
     64 
     65 	usec_spin(co->cpucycle);
     66 	return FIO_Q_COMPLETED;
     67 }
     68 
     69 static int fio_cpuio_init(struct thread_data *td)
     70 {
     71 	struct thread_options *o = &td->o;
     72 	struct cpu_options *co = td->eo;
     73 
     74 	if (!co->cpuload) {
     75 		td_vmsg(td, EINVAL, "cpu thread needs rate (cpuload=)","cpuio");
     76 		return 1;
     77 	}
     78 
     79 	if (co->cpuload > 100)
     80 		co->cpuload = 100;
     81 
     82 	/*
     83 	 * set thinktime_sleep and thinktime_spin appropriately
     84 	 */
     85 	o->thinktime_blocks = 1;
     86 	o->thinktime_spin = 0;
     87 	o->thinktime = (co->cpucycle * (100 - co->cpuload)) / co->cpuload;
     88 
     89 	o->nr_files = o->open_files = 1;
     90 
     91 	log_info("%s: ioengine=%s, cpuload=%u, cpucycle=%u\n",
     92 		td->o.name, td->io_ops->name, co->cpuload, co->cpucycle);
     93 
     94 	return 0;
     95 }
     96 
     97 static int fio_cpuio_open(struct thread_data fio_unused *td,
     98 			  struct fio_file fio_unused *f)
     99 {
    100 	return 0;
    101 }
    102 
    103 static struct ioengine_ops ioengine = {
    104 	.name		= "cpuio",
    105 	.version	= FIO_IOOPS_VERSION,
    106 	.queue		= fio_cpuio_queue,
    107 	.init		= fio_cpuio_init,
    108 	.open_file	= fio_cpuio_open,
    109 	.flags		= FIO_SYNCIO | FIO_DISKLESSIO | FIO_NOIO,
    110 	.options		= options,
    111 	.option_struct_size	= sizeof(struct cpu_options),
    112 };
    113 
    114 static void fio_init fio_cpuio_register(void)
    115 {
    116 	register_ioengine(&ioengine);
    117 }
    118 
    119 static void fio_exit fio_cpuio_unregister(void)
    120 {
    121 	unregister_ioengine(&ioengine);
    122 }
    123