/*

 * CPU engine

 *

 * Doesn't transfer any data, merely burns CPU cycles according to

 * the settings.

 *

 */

#include "../fio.h"

#include "../optgroup.h"

struct cpu_options {

	void *pad;

	unsigned int cpuload;

	unsigned int cpucycle;

	unsigned int exit_io_done;

};

static struct fio_option options[] = {

	{

		.name	= "cpuload",

		.lname	= "CPU load",

		.type	= FIO_OPT_INT,

		.off1	= offsetof(struct cpu_options, cpuload),

		.help	= "Use this percentage of CPU",

		.category = FIO_OPT_C_ENGINE,

		.group	= FIO_OPT_G_INVALID,

	},

	{

		.name	= "cpuchunks",

		.lname	= "CPU chunk",

		.type	= FIO_OPT_INT,

		.off1	= offsetof(struct cpu_options, cpucycle),

		.help	= "Length of the CPU burn cycles (usecs)",

		.def	= "50000",

		.parent = "cpuload",

		.hide	= 1,

		.category = FIO_OPT_C_ENGINE,

		.group	= FIO_OPT_G_INVALID,

	},

	{

		.name	= "exit_on_io_done",

		.lname	= "Exit when IO threads are done",

		.type	= FIO_OPT_BOOL,

		.off1	= offsetof(struct cpu_options, exit_io_done),

		.help	= "Exit when IO threads finish",

		.def	= "0",

		.category = FIO_OPT_C_ENGINE,

		.group	= FIO_OPT_G_INVALID,

	},

	{

		.name	= NULL,

	},

};

static enum fio_q_status fio_cpuio_queue(struct thread_data *td,

					 struct io_u fio_unused *io_u)

{

	struct cpu_options *co = td->eo;

	if (co->exit_io_done && !fio_running_or_pending_io_threads()) {

		td->done = 1;

		return FIO_Q_BUSY;

	}

	usec_spin(co->cpucycle);

	return FIO_Q_COMPLETED;

}

static int fio_cpuio_init(struct thread_data *td)

{

	struct thread_options *o = &td->o;

	struct cpu_options *co = td->eo;

	if (!co->cpuload) {

		td_vmsg(td, EINVAL, "cpu thread needs rate (cpuload=)","cpuio");

		return 1;

	}

	if (co->cpuload > 100)

		co->cpuload = 100;

	/*

	 * set thinktime_sleep and thinktime_spin appropriately

	 */

	o->thinktime_blocks = 1;

	o->thinktime_spin = 0;

	o->thinktime = ((unsigned long long) co->cpucycle * (100 - co->cpuload)) / co->cpuload;

	o->nr_files = o->open_files = 1;

	log_info("%s: ioengine=%s, cpuload=%u, cpucycle=%u\n",

		td->o.name, td->io_ops->name, co->cpuload, co->cpucycle);

	return 0;

}

static int fio_cpuio_open(struct thread_data fio_unused *td,

			  struct fio_file fio_unused *f)

{

	return 0;

}

static struct ioengine_ops ioengine = {

	.name		= "cpuio",

	.version	= FIO_IOOPS_VERSION,

	.queue		= fio_cpuio_queue,

	.init		= fio_cpuio_init,

	.open_file	= fio_cpuio_open,

	.flags		= FIO_SYNCIO | FIO_DISKLESSIO | FIO_NOIO,

	.options		= options,

	.option_struct_size	= sizeof(struct cpu_options),

};

static void fio_init fio_cpuio_register(void)

{

	register_ioengine(&ioengine);

}

static void fio_exit fio_cpuio_unregister(void)

{

	unregister_ioengine(&ioengine);

}