diff options
| author | Steven Rostedt <rostedt@goodmis.org> | 2013-08-19 17:33:26 -0400 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2013-09-07 20:56:32 -0400 |
| commit | 233994b62ad27261108bf2a694ac35b7c45ef1a9 (patch) | |
| tree | 29431017b9bfe90f2ade90c28f5c038ee2f4eeb8 | |
| parent | 4c0403f02ab8ef5e5a689e80239ebb65ec328f44 (diff) | |
hwlat-detector: Use trace_clock_local if available
As ktime_get() calls into the timing code which does a read_seq(), it
may be affected by other CPUS that touch that lock. To remove this
dependency, use the trace_clock_local() which is already exported
for module use. If CONFIG_TRACING is enabled, use that as the clock,
otherwise use ktime_get().
Cc: stable-rt@vger.kernel.org
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
| -rw-r--r-- | drivers/misc/hwlat_detector.c | 34 |
1 files changed, 25 insertions, 9 deletions
diff --git a/drivers/misc/hwlat_detector.c b/drivers/misc/hwlat_detector.c index f93b8ef7ec0f..13443e9a3452 100644 --- a/drivers/misc/hwlat_detector.c +++ b/drivers/misc/hwlat_detector.c @@ -51,6 +51,7 @@ #include <linux/version.h> #include <linux/delay.h> #include <linux/slab.h> +#include <linux/trace_clock.h> #define BUF_SIZE_DEFAULT 262144UL /* 8K*(sizeof(entry)) */ #define BUF_FLAGS (RB_FL_OVERWRITE) /* no block on full */ @@ -211,6 +212,21 @@ static struct sample *buffer_get_sample(struct sample *sample) return sample; } +#ifndef CONFIG_TRACING +#define time_type ktime_t +#define time_get() ktime_get() +#define time_to_us(x) ktime_to_us(x) +#define time_sub(a, b) ktime_sub(a, b) +#define init_time(a, b) (a).tv64 = b +#define time_u64(a) (a).tv64 +#else +#define time_type u64 +#define time_get() trace_clock_local() +#define time_to_us(x) div_u64(x, 1000) +#define time_sub(a, b) ((a) - (b)) +#define init_time(a, b) a = b +#define time_u64(a) a +#endif /** * get_sample - sample the CPU TSC and look for likely hardware latencies * @unused: This is not used but is a part of the stop_machine API @@ -220,23 +236,23 @@ static struct sample *buffer_get_sample(struct sample *sample) */ static int get_sample(void *unused) { - ktime_t start, t1, t2, last_t2; + time_type start, t1, t2, last_t2; s64 diff, total = 0; u64 sample = 0; u64 outer_sample = 0; int ret = 1; - last_t2.tv64 = 0; - start = ktime_get(); /* start timestamp */ + init_time(last_t2, 0); + start = time_get(); /* start timestamp */ do { - t1 = ktime_get(); /* we'll look for a discontinuity */ - t2 = ktime_get(); + t1 = time_get(); /* we'll look for a discontinuity */ + t2 = time_get(); - if (last_t2.tv64) { + if (time_u64(last_t2)) { /* Check the delta from the outer loop (t2 to next t1) */ - diff = ktime_to_us(ktime_sub(t1, last_t2)); + diff = time_to_us(time_sub(t1, last_t2)); /* This shouldn't happen */ if (diff < 0) { printk(KERN_ERR BANNER "time running backwards\n"); @@ -247,10 +263,10 @@ static int get_sample(void *unused) } last_t2 = t2; - total = ktime_to_us(ktime_sub(t2, start)); /* sample width */ + total = time_to_us(time_sub(t2, start)); /* sample width */ /* This checks the inner loop (t1 to t2) */ - diff = ktime_to_us(ktime_sub(t2, t1)); /* current diff */ + diff = time_to_us(time_sub(t2, t1)); /* current diff */ /* This shouldn't happen */ if (diff < 0) { |