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Diffstat (limited to 'mini-os/time.c')
| -rw-r--r-- | mini-os/time.c | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/mini-os/time.c b/mini-os/time.c new file mode 100644 index 0000000000..ff23b2ee63 --- /dev/null +++ b/mini-os/time.c @@ -0,0 +1,149 @@ +/* -*- Mode:C; c-basic-offset:4; tab-width:4 -*- + **************************************************************************** + * (C) 2003 - Rolf Neugebauer - Intel Research Cambridge + **************************************************************************** + * + * File: time.c + * Author: Rolf Neugebauer (neugebar@dcs.gla.ac.uk) + * Changes: + * + * Date: Jul 2003 + * + * Environment: Xen Minimal OS + * Description: Simple time and timer functions + * + **************************************************************************** + * $Id: c-insert.c,v 1.7 2002/11/08 16:04:34 rn Exp $ + **************************************************************************** + */ + + +#include <os.h> +#include <types.h> +#include <hypervisor.h> +#include <events.h> +#include <time.h> +#include <lib.h> + +/************************************************************************ + * Time functions + *************************************************************************/ + +static unsigned int rdtsc_bitshift; +static u32 st_scale_f; +static u32 st_scale_i; +static u32 shadow_st_pcc; +static s_time_t shadow_st; +static u32 shadow_wc_version=0; +static long shadow_tv_sec; +static long shadow_tv_usec; +static s_time_t shadow_wc_timestamp; + +/* + * System time. + * We need to read the values from the shared info page "atomically" + * and use the cycle counter value as the "version" number. Clashes + * should be very rare. + */ +inline s_time_t get_s_time(void) +{ + s32 delta_tsc; + u32 low; + u64 delta, tsc; + u32 version; + u64 cpu_freq, scale; + + /* check if our values are still up-to-date */ + while ( (version = HYPERVISOR_shared_info->wc_version) != + shadow_wc_version ) + { + barrier(); + + shadow_wc_version = version; + shadow_tv_sec = HYPERVISOR_shared_info->tv_sec; + shadow_tv_usec = HYPERVISOR_shared_info->tv_usec; + shadow_wc_timestamp = HYPERVISOR_shared_info->wc_timestamp; + shadow_st_pcc = HYPERVISOR_shared_info->st_timestamp; + shadow_st = HYPERVISOR_shared_info->system_time; + + rdtsc_bitshift = HYPERVISOR_shared_info->rdtsc_bitshift; + cpu_freq = HYPERVISOR_shared_info->cpu_freq; + + /* XXX cpu_freq as u32 limits it to 4.29 GHz. Get a better do_div! */ + scale = 1000000000LL << (32 + rdtsc_bitshift); + scale /= cpu_freq; + st_scale_f = scale & 0xffffffff; + st_scale_i = scale >> 32; + + barrier(); + } + + rdtscll(tsc); + low = (u32)(tsc >> rdtsc_bitshift); + delta_tsc = (s32)(low - shadow_st_pcc); + if ( unlikely(delta_tsc < 0) ) delta_tsc = 0; + delta = ((u64)delta_tsc * st_scale_f); + delta >>= 32; + delta += ((u64)delta_tsc * st_scale_i); + + return shadow_st + delta; +} + + +/* + * Wallclock time. + * Based on what the hypervisor tells us, extrapolated using system time. + * Again need to read a number of values from the shared page "atomically". + * this time using a version number. + */ +void gettimeofday(struct timeval *tv) +{ + long usec, sec; + u64 now; + + now = get_s_time(); + usec = ((unsigned long)(now-shadow_wc_timestamp))/1000; + sec = shadow_tv_sec; + usec += shadow_tv_usec; + + while ( usec >= 1000000 ) + { + usec -= 1000000; + sec++; + } + + tv->tv_sec = sec; + tv->tv_usec = usec; +} + + +static void timer_handler(int ev, struct pt_regs *regs) +{ + static int i; + s_time_t now; + + i++; + if (i >= 1000) { + now = get_s_time(); + printf("T(%lld)\n", now); + i = 0; + } +} + + +void init_time(void) +{ + u64 __cpu_khz; + unsigned long cpu_khz; + + __cpu_khz = HYPERVISOR_shared_info->cpu_freq; + cpu_khz = (u32) (__cpu_khz/1000); + + printk("Xen reported: %lu.%03lu MHz processor.\n", + cpu_khz / 1000, cpu_khz % 1000); + + add_ev_action(EV_TIMER, &timer_handler); + enable_ev_action(EV_TIMER); + enable_hypervisor_event(EV_TIMER); + +} |