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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2007-02-05 15:18:31 -0500
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2007-02-05 15:18:31 -0500
commit31ee4b2f40994e8b21691f85cdd4052551a789b7 (patch)
tree1bb167e720e25a2ea9a5168b21cc882f85b18fa8 /drivers/s390/sysinfo.c
parent31cb4bd31a48f62105d037ad53192b94d4c08f53 (diff)
[S390] Calibrate delay and bogomips.
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>
Diffstat (limited to 'drivers/s390/sysinfo.c')
-rw-r--r--drivers/s390/sysinfo.c63
1 files changed, 62 insertions, 1 deletions
diff --git a/drivers/s390/sysinfo.c b/drivers/s390/sysinfo.c
index 1e788e815ce7..090743d2f914 100644
--- a/drivers/s390/sysinfo.c
+++ b/drivers/s390/sysinfo.c
@@ -9,8 +9,14 @@
9#include <linux/mm.h> 9#include <linux/mm.h>
10#include <linux/proc_fs.h> 10#include <linux/proc_fs.h>
11#include <linux/init.h> 11#include <linux/init.h>
12#include <linux/delay.h>
12#include <asm/ebcdic.h> 13#include <asm/ebcdic.h>
13 14
15/* Sigh, math-emu. Don't ask. */
16#include <asm/sfp-util.h>
17#include <math-emu/soft-fp.h>
18#include <math-emu/single.h>
19
14struct sysinfo_1_1_1 { 20struct sysinfo_1_1_1 {
15 char reserved_0[32]; 21 char reserved_0[32];
16 char manufacturer[16]; 22 char manufacturer[16];
@@ -198,7 +204,7 @@ static int stsi_1_2_2(struct sysinfo_1_2_2 *info, char *page, int len)
198 * if the higher order 8 bits are not zero. Printing 204 * if the higher order 8 bits are not zero. Printing
199 * a floating point number in the kernel is a no-no, 205 * a floating point number in the kernel is a no-no,
200 * always print the number as 32 bit unsigned integer. 206 * always print the number as 32 bit unsigned integer.
201 * The user-space needs to know about the stange 207 * The user-space needs to know about the strange
202 * encoding of the alternate cpu capability. 208 * encoding of the alternate cpu capability.
203 */ 209 */
204 len += sprintf(page + len, "Capability: %u %u\n", 210 len += sprintf(page + len, "Capability: %u %u\n",
@@ -351,3 +357,58 @@ static __init int create_proc_sysinfo(void)
351 357
352__initcall(create_proc_sysinfo); 358__initcall(create_proc_sysinfo);
353 359
360/*
361 * CPU capability might have changed. Therefore recalculate loops_per_jiffy.
362 */
363void s390_adjust_jiffies(void)
364{
365 struct sysinfo_1_2_2 *info;
366 const unsigned int fmil = 0x4b189680; /* 1e7 as 32-bit float. */
367 FP_DECL_S(SA); FP_DECL_S(SB); FP_DECL_S(SR);
368 FP_DECL_EX;
369 unsigned int capability;
370
371 info = (void *) get_zeroed_page(GFP_KERNEL);
372 if (!info)
373 return;
374
375 if (stsi(info, 1, 2, 2) != -ENOSYS) {
376 /*
377 * Major sigh. The cpu capability encoding is "special".
378 * If the first 9 bits of info->capability are 0 then it
379 * is a 32 bit unsigned integer in the range 0 .. 2^23.
380 * If the first 9 bits are != 0 then it is a 32 bit float.
381 * In addition a lower value indicates a proportionally
382 * higher cpu capacity. Bogomips are the other way round.
383 * To get to a halfway suitable number we divide 1e7
384 * by the cpu capability number. Yes, that means a floating
385 * point division .. math-emu here we come :-)
386 */
387 FP_UNPACK_SP(SA, &fmil);
388 if ((info->capability >> 23) == 0)
389 FP_FROM_INT_S(SB, info->capability, 32, int);
390 else
391 FP_UNPACK_SP(SB, &info->capability);
392 FP_DIV_S(SR, SA, SB);
393 FP_TO_INT_S(capability, SR, 32, 0);
394 } else
395 /*
396 * Really old machine without stsi block for basic
397 * cpu information. Report 42.0 bogomips.
398 */
399 capability = 42;
400 loops_per_jiffy = capability * (500000/HZ);
401 free_page((unsigned long) info);
402}
403
404/*
405 * calibrate the delay loop
406 */
407void __init calibrate_delay(void)
408{
409 s390_adjust_jiffies();
410 /* Print the good old Bogomips line .. */
411 printk(KERN_DEBUG "Calibrating delay loop (skipped)... "
412 "%lu.%02lu BogoMIPS preset\n", loops_per_jiffy/(500000/HZ),
413 (loops_per_jiffy/(5000/HZ)) % 100);
414}