ref: 909323e92a4e694bff5908e500d8655ac1bbd932
dir: /sys/src/9/xen/xentimer.c/
#include "u.h" #include "../port/lib.h" #include "mem.h" #include "dat.h" #include "fns.h" #include "io.h" static vcpu_time_info_t shadow[MAX_VIRT_CPUS]; // XXX should be in Mach static ulong wallclock; static ulong wallclocksystime; /* * Return a consistent set of time parameters. */ static vcpu_time_info_t * getshadow(void) { vcpu_time_info_t *s, *t; t = &HYPERVISOR_shared_info->vcpu_info[m->machno].time; s = &shadow[m->machno]; // XXX place in mach struct while(t->version != s->version) { if (t->version&1) continue; s->version = t->version; s->tsc_timestamp = t->tsc_timestamp; s->system_time = t->system_time; s->tsc_to_system_mul = t->tsc_to_system_mul; s->tsc_shift = t->tsc_shift; } return s; } /* just get it from the shared info */ void xentimerinit(void) { vcpu_time_info_t *t; t = getshadow(); m->cpuhz = (1000000000LL << 32) / t->tsc_to_system_mul; if(t->tsc_shift < 0) m->cpuhz <<= -t->tsc_shift; else m->cpuhz >>= t->tsc_shift; m->cpumhz = m->cpuhz / 1000000L; } void xentimerset(uvlong next) { uvlong soon; soon = fastticks(0) + 100000; if (next < soon) next = soon; HYPERVISOR_set_timer_op(next); } void xentimerclock(Ureg* ureg, void*) { timerintr(ureg, 0); } void xentimerenable(void) { intrenable(VIRQ_TIMER, xentimerclock, nil, 0, "clock"); } uvlong xentimerread(uvlong *hz) { uvlong x; uvlong delta, sdelta; vcpu_time_info_t *t; t = getshadow(); cycles(&x); delta = x - t->tsc_timestamp; if (t->tsc_shift < 0) delta >>= -t->tsc_shift; else delta <<= t->tsc_shift; mul64fract(&sdelta, delta, t->tsc_to_system_mul); x = t->system_time + sdelta; if (HYPERVISOR_shared_info->wc_sec != wallclock) { wallclock = HYPERVISOR_shared_info->wc_sec; wallclocksystime = x; } if (hz) *hz = 1000000000; return x; } ulong xenwallclock() { ulong elapsed; elapsed = (ulong)((xentimerread(0) - wallclocksystime)/1000000000); return wallclock + elapsed; } void microdelay(int microsecs) { uvlong targ, hz; targ = xentimerread(&hz); targ += microsecs * hz / 1000000; while(xentimerread(0) < targ) continue; } void delay(int millisecs) { microdelay(millisecs * 1000); } /* * performance measurement ticks. must be low overhead. * doesn't have to count over a second. */ ulong perfticks(void) { uvlong x; cycles(&x); return x; }