* Andrew Morton <[email protected]> wrote:
> > * 2^30ns == 1.074s.
> > */
> > -static unsigned long get_timestamp(void)
> > +static unsigned long get_timestamp(int this_cpu)
> > {
> > - return sched_clock() >> 30; /* 2^30 ~= 10^9 */
> > + return cpu_clock(this_cpu) >> 30; /* 2^30 ~= 10^9 */
> > }
> >
> > void touch_softlockup_watchdog(void)
> > {
> > - __raw_get_cpu_var(touch_timestamp) = get_timestamp();
> > + int this_cpu = raw_smp_processor_id();
> > +
> > + per_cpu(touch_timestamp, this_cpu) = get_timestamp(this_cpu);
> > }
> > EXPORT_SYMBOL(touch_softlockup_watchdog);
> >
> > @@ -95,7 +97,7 @@ void softlockup_tick(void)
> > return;
>
> argh. afacit this was never sent, except as part of some jumbopatch
> called "sched: implement cpu_clock(cpu) high-speed time source".
>
> That patch helped.
>
> It's all a plot.
sorry, it's really my fault: i decoupled it from the jumbopatch (so that
the new API could go in first) but forgot to re-send that crutial bit.
There's also the patch below (Jens Cc:-ed) to update blktrace. I guess i
should do a softlockup.git tree to avoid such foul-ups in the future.
Ingo
----------------------->
Subject: blktrace: use cpu_clock() instead of sched_clock()
From: Ingo Molnar <[email protected]>
use cpu_clock() instead of sched_clock(). (the latter is not a proper
clock-source)
Signed-off-by: Ingo Molnar <[email protected]>
---
block/blktrace.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
Index: linux/block/blktrace.c
===================================================================
--- linux.orig/block/blktrace.c
+++ linux/block/blktrace.c
@@ -41,7 +41,7 @@ static void trace_note(struct blk_trace
const int cpu = smp_processor_id();
t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
- t->time = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu);
+ t->time = cpu_clock(cpu) - per_cpu(blk_trace_cpu_offset, cpu);
t->device = bt->dev;
t->action = action;
t->pid = pid;
@@ -159,7 +159,7 @@ void __blk_add_trace(struct blk_trace *b
t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
t->sequence = ++(*sequence);
- t->time = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu);
+ t->time = cpu_clock(cpu) - per_cpu(blk_trace_cpu_offset, cpu);
t->sector = sector;
t->bytes = bytes;
t->action = what;
@@ -488,17 +488,17 @@ void blk_trace_shutdown(request_queue_t
}
/*
- * Average offset over two calls to sched_clock() with a gettimeofday()
+ * Average offset over two calls to cpu_clock() with a gettimeofday()
* in the middle
*/
-static void blk_check_time(unsigned long long *t)
+static void blk_check_time(unsigned long long *t, int this_cpu)
{
unsigned long long a, b;
struct timeval tv;
- a = sched_clock();
+ a = cpu_clock(this_cpu);
do_gettimeofday(&tv);
- b = sched_clock();
+ b = cpu_clock(this_cpu);
*t = tv.tv_sec * 1000000000 + tv.tv_usec * 1000;
*t -= (a + b) / 2;
@@ -510,16 +510,16 @@ static void blk_check_time(unsigned long
static void blk_trace_check_cpu_time(void *data)
{
unsigned long long *t;
- int cpu = get_cpu();
+ int this_cpu = get_cpu();
- t = &per_cpu(blk_trace_cpu_offset, cpu);
+ t = &per_cpu(blk_trace_cpu_offset, this_cpu);
/*
* Just call it twice, hopefully the second call will be cache hot
* and a little more precise
*/
- blk_check_time(t);
- blk_check_time(t);
+ blk_check_time(t, this_cpu);
+ blk_check_time(t, this_cpu);
put_cpu();
}
-
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