[S390] hwsampler: Set a sane default sampling rate

The sampling interval for the hardware sampler is specified in cycles.
(see SA23-2260-01 The Load-Program-Parameter and the CPU-Measurement
Facilities)
The current default value will therefore result in millions of samples.
This patch changes the default sampling interval to 4M, which will
result in ~1500 samples per second on a z196 reducing the overhead
of sampling.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/oprofile/init.c b/arch/s390/oprofile/init.c
index 5e2ab03eaffde929fc1dc8256d2b2515332e902c..0e358c2cffeb5e6bf1955ba6ca2c3de7092e03b3 100644 (file)
--- a/arch/s390/oprofile/init.c
+++ b/arch/s390/oprofile/init.c
@@ -25,7 +25,7 @@ extern void s390_backtrace(struct pt_regs * const regs, unsigned int depth);
 
 #include "hwsampler.h"
 
-#define DEFAULT_INTERVAL       4096
+#define DEFAULT_INTERVAL       4127518
 
 #define DEFAULT_SDBT_BLOCKS    1
 #define DEFAULT_SDB_BLOCKS     511