Commit f3f3149f authored by Alok Kataria's avatar Alok Kataria Committed by Ingo Molnar
Browse files

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: default avatarAlok 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: default avatarIngo Molnar <mingo@elte.hu>
parent 6ff10de3

arch/x86/kernel/time_64.c

+1 −1
Original line number Diff line number Diff line
@@ -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");

arch/x86/kernel/tsc_32.c

+1 −1
Original line number Diff line number Diff line
@@ -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,

include/linux/delay.h

+1 −1
Original line number Diff line number Diff line
@@ -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);

init/calibrate.c

+19 −17
Original line number Diff line number Diff line
@@ -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.. ");

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