#include <u.h>
#include <libc.h>

int msrfd = -1;

static u64int
rdmsr(ulong msr)
{
	u64int val;
	uchar data[8];

	if(pread(msrfd, data, sizeof(data), msr) != sizeof(data))
		sysfatal("rdmsr: %r");

	val = data[0] | (data[1] << 8) |
		(data[2] << 16) | (data[3] << 24) |
		((vlong)data[4] << 32) | ((vlong)data[5] << 40) |
		((vlong)data[6] << 48) | ((vlong)data[7] << 56);

	return val;
}

static void
wrmsr(ulong msr, u64int val)
{
	uchar data[8];

	data[0] = val;
	data[1] = val >> 8;
	data[2] = val >> 16;
	data[3] = val >> 24;
	data[4] = val >> 32;
	data[5] = val >> 40;
	data[6] = val >> 48;
	data[7] = val >> 56;

	if(pwrite(msrfd, data, sizeof(data), msr) != sizeof(data))
		sysfatal("wrmsr: %r");
}

static void
pin(int cpu)
{
	char ctlbuf[64];
	int ctlfd;

	snprint(ctlbuf, sizeof(ctlbuf), "/proc/%d/ctl", getpid());

	ctlfd = open(ctlbuf, OWRITE);
	if(ctlfd < 0)
		sysfatal("open %s: %r", ctlbuf);

	if(fprint(ctlfd, "wired %d\n", cpu) < 0)
		sysfatal("write %s: %r", ctlbuf);

	close(ctlfd);
}

static int
pstate_min(void)
{
	return (rdmsr(0xCE) >> 40) & 0xFF;
}

static int
pstate_max(void)
{
	return (rdmsr(0xCE) >> 8) & 0xFF;
}

static int
pstate_status(void)
{
	u64int pstate;

	// IA32_PERF_STATUS
	pstate = rdmsr(0x198);

	return (pstate & 0xFFFF) >> 8;
}

static void
pstate_ctlw(int pstate)
{
	// IA32_PERF_CTL
	wrmsr(0x199, (pstate & 0xFF) << 8);
}

static int
pstate_ctlr(void)
{
	u64int ctl;

	ctl = rdmsr(0x199);

	return (ctl & 0xFFFF) >> 8;
}

static u64int
mperf(void)
{
	return rdmsr(0xE7);
}

static u64int
aperf(void)
{
	return rdmsr(0xE8);
}

static int
load(void)
{
	char buf[8192], *lines[32], *f[10];
	int i, fd, ncpu, nf, lv, load;

	load = 0;

	fd = open("#c/sysstat", OREAD);
	if(fd < 0)
		sysfatal("open sysstat: %r");

	if(read(fd, buf, sizeof(buf)) < 0)
		sysfatal("read sysstat: %r");

	fprint(2, "sysstat:\n%s\n", buf);

	ncpu = gettokens(buf, lines, nelem(lines), "\n");
	if(ncpu < 1)
		sysfatal("no cpus???");

	/* sum in idle */

	for(i = 0; i < ncpu; i++){
		nf =tokenize(lines[i], f, nelem(f));
		if(nf != nelem(f))
			sysfatal("weird sysstat line: %d fields", nf);

		lv = atoi(f[8]);

		load += 100 - lv;
	}

	load /= ncpu;

	return load;
}

void
main(int argc, char *argv[])
{
	ARGBEGIN{
	}ARGEND

	msrfd = open("#P/msr", ORDWR);
	if(msrfd < 0)
		sysfatal("open msr: %r");

	int min, max;

	min = pstate_min();
	max = pstate_max();

	print("pstate min %d max %d\n", min, max);

	int status, ctl;
	status = pstate_status();
	ctl = pstate_ctlr();

	print("status %d ctl %d\n", status, ctl);

	print("mperf %llud aperf %llud\n", mperf(), aperf());

	u64int pctbusy = aperf()/mperf();

	print("ratio = %llud\n", pctbusy);

	print("load = %d%%\n", load());

	exits(nil);
}