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Removed some SMP ifdefs so that using the TSC as a cputime clock is

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not completely decided at config time.  Just don't default to using
the TSC if there are multiple active CPUs.  Also, don't default to
using the TSC if it is broken.  SMP ifdefs are still used to disallow
using perfmon since perfmon is always broken if SMP is just configured.

This only helps much for SMP kernels running on 1 CPU.  The overheads
for using the i8254 cputime clock were a bit too high on 486/33's, and
now on multi-GHz CPUs they are usually in the 99-99.9% range.  Switching
from the old default of an i8254 clock to the TSC works poorly because
the overheads are not recalibrated.

Use the same condition for declaring perfmon stuff as for using it.
This commit is contained in:
Bruce Evans 2006-10-29 09:48:44 +00:00
parent 0c2b04b419
commit 6a70163fcc
2 changed files with 15 additions and 19 deletions
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15
sys/amd64/amd64/prof_machdep.c
View File

@ -37,6 +37,7 @@ __FBSDID("$FreeBSD$");
#include <sys/systm.h>
#include <sys/gmon.h>
#include <sys/kernel.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <machine/clock.h>
@ -54,7 +55,7 @@ __FBSDID("$FreeBSD$");
int cputime_bias = 1; /* initialize for locality of reference */
static int cputime_clock = CPUTIME_CLOCK_UNINITIALIZED;
#ifdef I586_PMC_GUPROF
#if defined(PERFMON) && defined(I586_PMC_GUPROF)
static u_int cputime_clock_pmc_conf = I586_PMC_GUPROF;
static int cputime_clock_pmc_init;
static struct gmonparam saved_gmp;
@ -204,7 +205,6 @@ cputime()
u_char high, low;
static u_int prev_count;
#ifndef SMP
if (cputime_clock == CPUTIME_CLOCK_TSC) {
/*
* Scale the TSC a little to make cputime()'s frequency
@ -218,7 +218,7 @@ cputime()
prev_count = count;
return (delta);
}
#if defined(PERFMON) && defined(I586_PMC_GUPROF)
#if defined(PERFMON) && defined(I586_PMC_GUPROF) && !defined(SMP)
if (cputime_clock == CPUTIME_CLOCK_I586_PMC) {
/*
* XXX permon_read() should be inlined so that the
@ -232,8 +232,7 @@ cputime()
prev_count = count;
return (delta);
}
#endif /* PERFMON && I586_PMC_GUPROF */
#endif /* !SMP */
#endif /* PERFMON && I586_PMC_GUPROF && !SMP */
/*
* Read the current value of the 8254 timer counter 0.
@ -315,13 +314,10 @@ startguprof(gp)
{
if (cputime_clock == CPUTIME_CLOCK_UNINITIALIZED) {
cputime_clock = CPUTIME_CLOCK_I8254;
#ifndef SMP
if (tsc_freq != 0)
if (tsc_freq != 0 && !tsc_is_broken && mp_ncpus < 2)
cputime_clock = CPUTIME_CLOCK_TSC;
#endif
}
gp->profrate = timer_freq << CPUTIME_CLOCK_I8254_SHIFT;
#ifndef SMP
if (cputime_clock == CPUTIME_CLOCK_TSC)
gp->profrate = tsc_freq >> 1;
#if defined(PERFMON) && defined(I586_PMC_GUPROF)
@ -350,7 +346,6 @@ startguprof(gp)
}
}
#endif /* PERFMON && I586_PMC_GUPROF */
#endif /* !SMP */
cputime_bias = 0;
cputime();
}

19
sys/i386/isa/prof_machdep.c
View File

@ -35,6 +35,7 @@ __FBSDID("$FreeBSD$");
#include <sys/systm.h>
#include <sys/gmon.h>
#include <sys/kernel.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <machine/clock.h>
@ -50,7 +51,7 @@ __FBSDID("$FreeBSD$");
int cputime_bias = 1; /* initialize for locality of reference */
static int cputime_clock = CPUTIME_CLOCK_UNINITIALIZED;
#ifdef I586_PMC_GUPROF
#if defined(PERFMON) && defined(I586_PMC_GUPROF)
static u_int cputime_clock_pmc_conf = I586_PMC_GUPROF;
static int cputime_clock_pmc_init;
static struct gmonparam saved_gmp;
@ -174,7 +175,7 @@ cputime()
u_char high, low;
static u_int prev_count;
#if (defined(I586_CPU) || defined(I686_CPU)) && !defined(SMP)
#if defined(I586_CPU) || defined(I686_CPU)
if (cputime_clock == CPUTIME_CLOCK_TSC) {
/*
* Scale the TSC a little to make cputime()'s frequency
@ -188,7 +189,7 @@ cputime()
prev_count = count;
return (delta);
}
#if defined(PERFMON) && defined(I586_PMC_GUPROF)
#if defined(PERFMON) && defined(I586_PMC_GUPROF) && !defined(SMP)
if (cputime_clock == CPUTIME_CLOCK_I586_PMC) {
/*
* XXX permon_read() should be inlined so that the
@ -202,8 +203,8 @@ cputime()
prev_count = count;
return (delta);
}
#endif /* PERFMON && I586_PMC_GUPROF */
#endif /* (I586_CPU || I686_CPU) && !SMP */
#endif /* PERFMON && I586_PMC_GUPROF && !SMP */
#endif /* I586_CPU || I686_CPU */
/*
* Read the current value of the 8254 timer counter 0.
@ -285,13 +286,13 @@ startguprof(gp)
{
if (cputime_clock == CPUTIME_CLOCK_UNINITIALIZED) {
cputime_clock = CPUTIME_CLOCK_I8254;
#if (defined(I586_CPU) || defined(I686_CPU)) && !defined(SMP)
if (tsc_freq != 0)
#if defined(I586_CPU) || defined(I686_CPU)
if (tsc_freq != 0 && !tsc_is_broken && mp_ncpus < 2)
cputime_clock = CPUTIME_CLOCK_TSC;
#endif
}
gp->profrate = timer_freq << CPUTIME_CLOCK_I8254_SHIFT;
#if (defined(I586_CPU) || defined(I686_CPU)) && !defined(SMP)
#if defined(I586_CPU) || defined(I686_CPU)
if (cputime_clock == CPUTIME_CLOCK_TSC)
gp->profrate = tsc_freq >> 1;
#if defined(PERFMON) && defined(I586_PMC_GUPROF)
@ -320,7 +321,7 @@ startguprof(gp)
}
}
#endif /* PERFMON && I586_PMC_GUPROF */
#endif /* (I586_CPU || I686_CPU) && !SMP */
#endif /* I586_CPU || I686_CPU */
cputime_bias = 0;
cputime();
}