[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>
diff --git a/drivers/s390/sysinfo.c b/drivers/s390/sysinfo.c
index 1e788e8..090743d 100644
--- a/drivers/s390/sysinfo.c
+++ b/drivers/s390/sysinfo.c
@@ -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 @@
* 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 @@
__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);
+}