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authorChristian Borntraeger <borntraeger@de.ibm.com>2008-11-27 11:05:56 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2008-11-27 11:06:57 +0100
commit8107d8296baff899db89c1716fe8af69a5b19d18 (patch)
tree0babc3276a83c75d3f51f868149c468b34331cc4 /arch
parent59da21398e680e8100625d689c8bebee6a139e93 (diff)
[S390] fix/cleanup sched_clock
CONFIG_PRINTK_TIME reveals that sched_clock has a wrong offset during boot: .. [ 0.000000] Movable zone: 0 pages used for memmap [ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 775679 [ 0.000000] Kernel command line: dasd=4b6c root=/dev/dasda1 ro noinitrd [ 0.000000] PID hash table entries: 4096 (order: 12, 32768 bytes) [6920575.975232] console [ttyS0] enabled [6920575.987586] Dentry cache hash table entries: 524288 (order: 10, 4194304 bytes) [6920575.991404] Inode-cache hash table entries: 262144 (order: 9, 2097152 bytes) .. The s390 implementation of sched_clock uses the store clock instruction and subtracts jiffies_timer_cc. jiffies_timer_cc is a local variable in arch/s390/kernel/time.c and only used for sched_clock and monotonic clock. For historical reasons there is an offset on that value. With todays code this offset is unnecessary. By removing that offset we can get a sched_clock which returns the nanoseconds after time_init. This improves CONFIG_PRINTK_TIME. Since sched_clock is the only user, I have also renamed jiffies_timer_cc to sched_clock_base_cc. In addition, the local variable init_timer_cc is redundant and can be romved as well. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/s390/kernel/time.c13
1 files changed, 5 insertions, 8 deletions
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index b94e9e3b694a..eccefbbff887 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -59,7 +59,7 @@
static ext_int_info_t ext_int_info_cc;
static ext_int_info_t ext_int_etr_cc;
-static u64 jiffies_timer_cc;
+static u64 sched_clock_base_cc;
static DEFINE_PER_CPU(struct clock_event_device, comparators);
@@ -68,7 +68,7 @@ static DEFINE_PER_CPU(struct clock_event_device, comparators);
*/
unsigned long long sched_clock(void)
{
- return ((get_clock_xt() - jiffies_timer_cc) * 125) >> 9;
+ return ((get_clock_xt() - sched_clock_base_cc) * 125) >> 9;
}
/*
@@ -229,13 +229,10 @@ static struct clocksource clocksource_tod = {
*/
void __init time_init(void)
{
- u64 init_timer_cc;
-
- init_timer_cc = reset_tod_clock();
- jiffies_timer_cc = init_timer_cc - jiffies_64 * CLK_TICKS_PER_JIFFY;
+ sched_clock_base_cc = reset_tod_clock();
/* set xtime */
- tod_to_timeval(init_timer_cc - TOD_UNIX_EPOCH, &xtime);
+ tod_to_timeval(sched_clock_base_cc - TOD_UNIX_EPOCH, &xtime);
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
@@ -289,7 +286,7 @@ static unsigned long long adjust_time(unsigned long long old,
delta = -delta;
adjust.offset = -ticks * (1000000 / HZ);
}
- jiffies_timer_cc += delta;
+ sched_clock_base_cc += delta;
if (adjust.offset != 0) {
printk(KERN_NOTICE "etr: time adjusted by %li micro-seconds\n",
adjust.offset);