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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 
     10 struct cpu_options {
     11 	struct thread_data *td;
     12 	unsigned int cpuload;
     13 	unsigned int cpucycle;
     14 	unsigned int exit_io_done;
     15 };
     16 
     17 static struct fio_option options[] = {
     18 	{
     19 		.name	= "cpuload",
     20 		.lname	= "CPU load",
     21 		.type	= FIO_OPT_INT,
     22 		.off1	= offsetof(struct cpu_options, cpuload),
     23 		.help	= "Use this percentage of CPU",
     24 		.category = FIO_OPT_C_GENERAL,
     25 		.group	= FIO_OPT_G_INVALID,
     26 	},
     27 	{
     28 		.name	= "cpuchunks",
     29 		.lname	= "CPU chunk",
     30 		.type	= FIO_OPT_INT,
     31 		.off1	= offsetof(struct cpu_options, cpucycle),
     32 		.help	= "Length of the CPU burn cycles (usecs)",
     33 		.def	= "50000",
     34 		.parent = "cpuload",
     35 		.hide	= 1,
     36 		.category = FIO_OPT_C_GENERAL,
     37 		.group	= FIO_OPT_G_INVALID,
     38 	},
     39 	{
     40 		.name	= "exit_on_io_done",
     41 		.lname	= "Exit when IO threads are done",
     42 		.type	= FIO_OPT_BOOL,
     43 		.off1	= offsetof(struct cpu_options, exit_io_done),
     44 		.help	= "Exit when IO threads finish",
     45 		.def	= "0",
     46 		.category = FIO_OPT_C_GENERAL,
     47 		.group	= FIO_OPT_G_INVALID,
     48 	},
     49 	{
     50 		.name	= NULL,
     51 	},
     52 };
     53 
     54 
     55 static int fio_cpuio_queue(struct thread_data *td, struct io_u fio_unused *io_u)
     56 {
     57 	struct cpu_options *co = td->eo;
     58 
     59 	if (co->exit_io_done && !fio_running_or_pending_io_threads()) {
     60 		td->done = 1;
     61 		return FIO_Q_BUSY;
     62 	}
     63 
     64 	usec_spin(co->cpucycle);
     65 	return FIO_Q_COMPLETED;
     66 }
     67 
     68 static int fio_cpuio_init(struct thread_data *td)
     69 {
     70 	struct thread_options *o = &td->o;
     71 	struct cpu_options *co = td->eo;
     72 
     73 	if (!co->cpuload) {
     74 		td_vmsg(td, EINVAL, "cpu thread needs rate (cpuload=)","cpuio");
     75 		return 1;
     76 	}
     77 
     78 	if (co->cpuload > 100)
     79 		co->cpuload = 100;
     80 
     81 	/*
     82 	 * set thinktime_sleep and thinktime_spin appropriately
     83 	 */
     84 	o->thinktime_blocks = 1;
     85 	o->thinktime_spin = 0;
     86 	o->thinktime = (co->cpucycle * (100 - co->cpuload)) / co->cpuload;
     87 
     88 	o->nr_files = o->open_files = 1;
     89 
     90 	log_info("%s: ioengine=cpu, cpuload=%u, cpucycle=%u\n", td->o.name,
     91 						co->cpuload, co->cpucycle);
     92 
     93 	return 0;
     94 }
     95 
     96 static int fio_cpuio_open(struct thread_data fio_unused *td,
     97 			  struct fio_file fio_unused *f)
     98 {
     99 	return 0;
    100 }
    101 
    102 static struct ioengine_ops ioengine = {
    103 	.name		= "cpuio",
    104 	.version	= FIO_IOOPS_VERSION,
    105 	.queue		= fio_cpuio_queue,
    106 	.init		= fio_cpuio_init,
    107 	.open_file	= fio_cpuio_open,
    108 	.flags		= FIO_SYNCIO | FIO_DISKLESSIO | FIO_NOIO,
    109 	.options		= options,
    110 	.option_struct_size	= sizeof(struct cpu_options),
    111 };
    112 
    113 static void fio_init fio_cpuio_register(void)
    114 {
    115 	register_ioengine(&ioengine);
    116 }
    117 
    118 static void fio_exit fio_cpuio_unregister(void)
    119 {
    120 	unregister_ioengine(&ioengine);
    121 }
    122