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[S390] Calibrate delay and bogomips.

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Preset the bogomips number to the cpu capacity value reported by
store system information in SYSIB 1.2.2. This value is constant
for a particular machine model and can be used to determine
relative performance differences between machines.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky
2007-02-05 21:18:31 +01:00
parent 31cb4bd31a
commit 31ee4b2f40
11 changed files with 149 additions and 88 deletions
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63
drivers/s390/sysinfo.c
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@@ -9,8 +9,14 @@
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <asm/ebcdic.h>
/* Sigh, math-emu. Don't ask. */
#include <asm/sfp-util.h>
#include <math-emu/soft-fp.h>
#include <math-emu/single.h>
struct sysinfo_1_1_1 {
char reserved_0[32];
char manufacturer[16];
@@ -198,7 +204,7 @@ static int stsi_1_2_2(struct sysinfo_1_2_2 *info, char *page, int len)
* if the higher order 8 bits are not zero. Printing
* a floating point number in the kernel is a no-no,
* always print the number as 32 bit unsigned integer.
* The user-space needs to know about the stange
* The user-space needs to know about the strange
* encoding of the alternate cpu capability.
*/
len += sprintf(page + len, "Capability: %u %u\n",
@@ -351,3 +357,58 @@ static __init int create_proc_sysinfo(void)
__initcall(create_proc_sysinfo);
/*
* CPU capability might have changed. Therefore recalculate loops_per_jiffy.
*/
void s390_adjust_jiffies(void)
{
struct sysinfo_1_2_2 *info;
const unsigned int fmil = 0x4b189680; /* 1e7 as 32-bit float. */
FP_DECL_S(SA); FP_DECL_S(SB); FP_DECL_S(SR);
FP_DECL_EX;
unsigned int capability;
info = (void *) get_zeroed_page(GFP_KERNEL);
if (!info)
return;
if (stsi(info, 1, 2, 2) != -ENOSYS) {
/*
* Major sigh. The cpu capability encoding is "special".
* If the first 9 bits of info->capability are 0 then it
* is a 32 bit unsigned integer in the range 0 .. 2^23.
* If the first 9 bits are != 0 then it is a 32 bit float.
* In addition a lower value indicates a proportionally
* higher cpu capacity. Bogomips are the other way round.
* To get to a halfway suitable number we divide 1e7
* by the cpu capability number. Yes, that means a floating
* point division .. math-emu here we come :-)
*/
FP_UNPACK_SP(SA, &fmil);
if ((info->capability >> 23) == 0)
FP_FROM_INT_S(SB, info->capability, 32, int);
else
FP_UNPACK_SP(SB, &info->capability);
FP_DIV_S(SR, SA, SB);
FP_TO_INT_S(capability, SR, 32, 0);
} else
/*
* Really old machine without stsi block for basic
* cpu information. Report 42.0 bogomips.
*/
capability = 42;
loops_per_jiffy = capability * (500000/HZ);
free_page((unsigned long) info);
}
/*
* calibrate the delay loop
*/
void __init calibrate_delay(void)
{
s390_adjust_jiffies();
/* Print the good old Bogomips line .. */
printk(KERN_DEBUG "Calibrating delay loop (skipped)... "
"%lu.%02lu BogoMIPS preset\n", loops_per_jiffy/(500000/HZ),
(loops_per_jiffy/(5000/HZ)) % 100);
}