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Kirill Smelkov
linux
Commits
9dcb3bd6
Commit
9dcb3bd6
authored
Jan 05, 2004
by
Dave Jones
Committed by
Dave Jones
Jan 05, 2004
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[CPUFREQ] on P4s no TSC adjustment is necessary
From Dominik Brodowski
parent
c33ccf2d
Changes
1
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1 changed file
with
27 additions
and
8 deletions
+27
-8
arch/i386/kernel/timers/timer_tsc.c
arch/i386/kernel/timers/timer_tsc.c
+27
-8
No files found.
arch/i386/kernel/timers/timer_tsc.c
View file @
9dcb3bd6
...
...
@@ -306,9 +306,17 @@ static void mark_offset_tsc_hpet(void)
}
#endif
#ifdef CONFIG_CPU_FREQ
/* If the CPU frequency is scaled, TSC-based delays will need a different
* loops_per_jiffy value to function properly. An exception to this
* are modern Intel Pentium 4 processors, where the TSC runs at a constant
* speed independent of frequency scaling.
*/
static
unsigned
int
ref_freq
=
0
;
static
unsigned
long
loops_per_jiffy_ref
=
0
;
static
unsigned
int
variable_tsc
=
1
;
#ifndef CONFIG_SMP
static
unsigned
long
fast_gettimeoffset_ref
=
0
;
...
...
@@ -333,12 +341,15 @@ time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
if
((
val
==
CPUFREQ_PRECHANGE
&&
freq
->
old
<
freq
->
new
)
||
(
val
==
CPUFREQ_POSTCHANGE
&&
freq
->
old
>
freq
->
new
))
{
cpu_data
[
freq
->
cpu
].
loops_per_jiffy
=
cpufreq_scale
(
loops_per_jiffy_ref
,
ref_freq
,
freq
->
new
);
if
(
variable_tsc
)
cpu_data
[
freq
->
cpu
].
loops_per_jiffy
=
cpufreq_scale
(
loops_per_jiffy_ref
,
ref_freq
,
freq
->
new
);
#ifndef CONFIG_SMP
if
(
use_tsc
)
{
fast_gettimeoffset_quotient
=
cpufreq_scale
(
fast_gettimeoffset_ref
,
freq
->
new
,
ref_freq
);
cpu_khz
=
cpufreq_scale
(
cpu_khz_ref
,
ref_freq
,
freq
->
new
);
set_cyc2ns_scale
(
cpu_khz
/
1000
);
if
(
variable_tsc
)
{
fast_gettimeoffset_quotient
=
cpufreq_scale
(
fast_gettimeoffset_ref
,
freq
->
new
,
ref_freq
);
set_cyc2ns_scale
(
cpu_khz
/
1000
);
}
}
#endif
}
...
...
@@ -350,7 +361,19 @@ time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
static
struct
notifier_block
time_cpufreq_notifier_block
=
{
.
notifier_call
=
time_cpufreq_notifier
};
#endif
static
int
__init
cpufreq_tsc
(
void
)
{
/* P4 and above CPU TSC freq doesn't change when CPU frequency changes*/
if
((
boot_cpu_data
.
x86
>=
15
)
&&
(
boot_cpu_data
.
x86_vendor
==
X86_VENDOR_INTEL
))
variable_tsc
=
0
;
return
cpufreq_register_notifier
(
&
time_cpufreq_notifier_block
,
CPUFREQ_TRANSITION_NOTIFIER
);
}
core_initcall
(
cpufreq_tsc
);
#endif
static
int
__init
init_tsc
(
char
*
override
)
...
...
@@ -392,10 +415,6 @@ static int __init init_tsc(char* override)
* some CPU's have a TSC. Thats never worked and nobody has
* moaned if you have the only one in the world - you fix it!
*/
#ifdef CONFIG_CPU_FREQ
cpufreq_register_notifier
(
&
time_cpufreq_notifier_block
,
CPUFREQ_TRANSITION_NOTIFIER
);
#endif
count2
=
LATCH
;
/* initialize counter for mark_offset_tsc() */
...
...
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