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x86: use cpu_khz for loops_per_jiffy calculation, cleanup 

As suggested by Ingo, remove all references to tsc from init/calibrate.c

TSC is x86 specific, and using tsc in variable names in a generic file should
be avoided. lpj_tsc is now called lpj_fine, since it is related to fine tuning
of lpj value. Also tsc_rate_*  is called timer_rate_*

Signed-off-by: Alok N Kataria <akataria@vmware.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Daniel Hecht <dhecht@vmware.com>
Cc: Tim Mann <mann@vmware.com>
Cc: Zach Amsden <zach@vmware.com>
Cc: Sahil Rihan <srihan@vmware.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Alok Kataria 2008-06-23 18:21:56 -07:00 committed by Ingo Molnar
parent 6ff10de374
commit f3f3149f35
4 changed files with 22 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/kernel/time_64.c
View File

@ -123,7 +123,7 @@ void __init time_init(void)
(boot_cpu_data.x86_vendor == X86_VENDOR_AMD))
cpu_khz = calculate_cpu_khz();
lpj_tsc = ((unsigned long)tsc_khz * 1000)/HZ;
lpj_fine = ((unsigned long)tsc_khz * 1000)/HZ;
if (unsynchronized_tsc())
mark_tsc_unstable("TSCs unsynchronized");

2
arch/x86/kernel/tsc_32.c
View File

@ -425,7 +425,7 @@ void __init tsc_init(void)
lpj = ((u64)tsc_khz * 1000);
do_div(lpj, HZ);
lpj_tsc = lpj;
lpj_fine = lpj;
printk("Detected %lu.%03lu MHz processor.\n",
(unsigned long)cpu_khz / 1000,

2
include/linux/delay.h
View File

@ -41,7 +41,7 @@ static inline void ndelay(unsigned long x)
#define ndelay(x) ndelay(x)
#endif
extern unsigned long lpj_tsc;
extern unsigned long lpj_fine;
void calibrate_delay(void);
void msleep(unsigned int msecs);
unsigned long msleep_interruptible(unsigned int msecs);

36
init/calibrate.c
View File

@ -10,7 +10,7 @@
#include <linux/timex.h>
#include <linux/smp.h>
unsigned long lpj_tsc;
unsigned long lpj_fine;
unsigned long preset_lpj;
static int __init lpj_setup(char *str)
{
@ -35,9 +35,9 @@ static unsigned long __cpuinit calibrate_delay_direct(void)
unsigned long pre_start, start, post_start;
unsigned long pre_end, end, post_end;
unsigned long start_jiffies;
unsigned long tsc_rate_min, tsc_rate_max;
unsigned long good_tsc_sum = 0;
unsigned long good_tsc_count = 0;
unsigned long timer_rate_min, timer_rate_max;
unsigned long good_timer_sum = 0;
unsigned long good_timer_count = 0;
int i;
if (read_current_timer(&pre_start) < 0 )
@ -81,22 +81,24 @@ static unsigned long __cpuinit calibrate_delay_direct(void)
}
read_current_timer(&post_end);
tsc_rate_max = (post_end - pre_start) / DELAY_CALIBRATION_TICKS;
tsc_rate_min = (pre_end - post_start) / DELAY_CALIBRATION_TICKS;
timer_rate_max = (post_end - pre_start) /
DELAY_CALIBRATION_TICKS;
timer_rate_min = (pre_end - post_start) /
DELAY_CALIBRATION_TICKS;
/*
* If the upper limit and lower limit of the tsc_rate is
* If the upper limit and lower limit of the timer_rate is
* >= 12.5% apart, redo calibration.
*/
if (pre_start != 0 && pre_end != 0 &&
(tsc_rate_max - tsc_rate_min) < (tsc_rate_max >> 3)) {
good_tsc_count++;
good_tsc_sum += tsc_rate_max;
(timer_rate_max - timer_rate_min) < (timer_rate_max >> 3)) {
good_timer_count++;
good_timer_sum += timer_rate_max;
}
}
if (good_tsc_count)
return (good_tsc_sum/good_tsc_count);
if (good_timer_count)
return (good_timer_sum/good_timer_count);
printk(KERN_WARNING "calibrate_delay_direct() failed to get a good "
"estimate for loops_per_jiffy.\nProbably due to long platform interrupts. Consider using \"lpj=\" boot option.\n");
@ -111,8 +113,8 @@ static unsigned long __cpuinit calibrate_delay_direct(void) {return 0;}
* bit takes on average 1.5/HZ seconds. This (like the original) is a little
* better than 1%
* For the boot cpu we can skip the delay calibration and assign it a value
* calculated based on the tsc frequency.
* For the rest of the CPUs we cannot assume that the tsc frequency is same as
* calculated based on the timer frequency.
* For the rest of the CPUs we cannot assume that the timer frequency is same as
* the cpu frequency, hence do the calibration for those.
*/
#define LPS_PREC 8
@ -126,11 +128,11 @@ void __cpuinit calibrate_delay(void)
loops_per_jiffy = preset_lpj;
printk(KERN_INFO
"Calibrating delay loop (skipped) preset value.. ");
} else if ((smp_processor_id() == 0) && lpj_tsc) {
loops_per_jiffy = lpj_tsc;
} else if ((smp_processor_id() == 0) && lpj_fine) {
loops_per_jiffy = lpj_fine;
printk(KERN_INFO
"Calibrating delay loop (skipped), "
"using tsc calculated value.. ");
"value calculated using timer frequency.. ");
} else if ((loops_per_jiffy = calibrate_delay_direct()) != 0) {
printk(KERN_INFO
"Calibrating delay using timer specific routine.. ");