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Microtime calculation was seriously incorrect when HZ != 100 

Give rest of clock interrupt code a revamp.  Because we are using an external
cycle counter we can now handle loosing several hundred interrupts without
the time slipping.
This commit is contained in:
wdk 2000-09-06 07:52:47 +00:00
parent 8f2cc012b5
commit b38096892a
3 changed files with 37 additions and 24 deletions
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7
sys/arch/mipsco/mipsco/machdep.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: machdep.c,v 1.6 2000/08/29 12:12:59 wdk Exp $ */
/* $NetBSD: machdep.c,v 1.7 2000/09/06 07:52:47 wdk Exp $ */
/*
* Copyright (c) 1988 University of Utah.
@ -43,7 +43,7 @@
#include <sys/cdefs.h> /* RCS ID & Copyright macro defns */
__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.6 2000/08/29 12:12:59 wdk Exp $");
__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.7 2000/09/06 07:52:47 wdk Exp $");
/* from: Utah Hdr: machdep.c 1.63 91/04/24 */
@ -570,13 +570,12 @@ microtime(tvp)
{
static struct timeval lasttime;
int s = splclock();
long rambo_getutime();
*tvp = time;
tvp->tv_usec += (*platform.clkread)();
if (tvp->tv_usec >= 1000000) {
while (tvp->tv_usec >= 1000000) {
tvp->tv_usec -= 1000000;
tvp->tv_sec++;
}

47
sys/arch/mipsco/obio/rambo.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: rambo.c,v 1.2 2000/08/15 04:56:47 wdk Exp $ */
/* $NetBSD: rambo.c,v 1.3 2000/09/06 07:52:47 wdk Exp $ */
/*
* Copyright (c) 2000 The NetBSD Foundation, Inc.
@ -104,7 +104,7 @@ rambo_attach(parent, self, aux)
/* Setup RAMBO Timer to generate timer interrupts */
sc->sc_hzticks = HZ_TO_TICKS(hz);
sc->sc_tclast = sc->sc_hzticks;
sc->sc_tclast = 0;
bus_space_write_4(sc->sc_bst, sc->sc_bsh, RB_TCOUNT, 0);
bus_space_write_4(sc->sc_bst, sc->sc_bsh, RB_TBREAK, sc->sc_hzticks);
@ -120,36 +120,49 @@ void
rambo_clkintr(cf)
struct clockframe *cf;
{
register u_int32_t tbreak, tclast;
register int cycles = 0;
register u_int32_t tbreak, tcount;
register int delta;
rambo->sc_intrcnt.ev_count++;
tbreak = bus_space_read_4(rambo->sc_bst, rambo->sc_bsh, RB_TBREAK);
/* This will also clear the interrupt */
while ((tclast=bus_space_read_4(rambo->sc_bst, rambo->sc_bsh,
RB_TCOUNT)) >= tbreak) {
tcount = bus_space_read_4(rambo->sc_bst, rambo->sc_bsh, RB_TCOUNT);
delta = tcount - tbreak;
if (delta > (rambo->sc_hzticks>>1)) {
/*
* Either tcount may overtake the updated tbreak value
* or we have missed several interrupt's
*/
int cycles = 10 * hz;
while (cycles && tbreak < tcount) {
hardclock(cf);
rambo->sc_tclast = tbreak;
tbreak += rambo->sc_hzticks;
cycles--;
}
if (cycles == 0) { /* catchup failed - assume we are in sync */
tcount = bus_space_read_4(rambo->sc_bst,
rambo->sc_bsh, RB_TCOUNT);
rambo->sc_tclast = tbreak = tcount;
}
} else {
hardclock(cf);
tbreak += rambo->sc_hzticks;
cycles++;
rambo->sc_tclast = tbreak;
}
tbreak += rambo->sc_hzticks;
bus_space_write_4(rambo->sc_bst, rambo->sc_bsh, RB_TBREAK, tbreak);
rambo->sc_tclast = tclast;
}
/*
* Calculate the number of microseconds since the last clock tick
*/
unsigned
static unsigned
rambo_clkread()
{
register u_int32_t tcount;
register u_int32_t tusec;
int s = splclock();
tcount = bus_space_read_4(rambo->sc_bst, rambo->sc_bsh, RB_TCOUNT);
tusec = TICKS_TO_USECS(tcount-rambo->sc_tclast, hz);
splx(s);
return tusec;
return TICKS_TO_USECS(tcount - rambo->sc_tclast);
}

5
sys/arch/mipsco/obio/rambo.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: rambo.h,v 1.1 2000/08/12 22:58:58 wdk Exp $ */
/* $NetBSD: rambo.h,v 1.2 2000/09/06 07:52:47 wdk Exp $ */
/*-
* Copyright (c) 2000 The NetBSD Foundation, Inc.
* All rights reserved.
@ -115,6 +115,7 @@ struct rambo_ch {
#define RB_BMASK ((1<<RB_BSIZE)-1)
#define RB_BOUNDRY (1<<RB_BSIZE)
/* Rambo cycle counter is fed by 25MHz clock then divided by 4 */
#define HZ_TO_TICKS(hz) (6250000L/(hz))
#define TICKS_TO_USECS(t, hz) ((t)*4/((hz)/4)) /* XXX */
#define TICKS_TO_USECS(t) ((t*4)/25)
#endif