Messages in this thread | | | Subject | Re: [PATCH v3 6/7] trace: events: add devfreq trace event file | From | Lukasz Luba <> | Date | Wed, 13 Feb 2019 14:35:01 +0100 |
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Hi Steven,
On 2/13/19 12:14 AM, Steven Rostedt wrote: > On Tue, 12 Feb 2019 23:23:57 +0100 > Lukasz Luba <l.luba@partner.samsung.com> wrote: > >> The patch adds a new file for with trace events for devfreq >> framework. They are used for performance analysis of the framework. >> It also contains updates in MAINTAINERS file adding new entry for >> devfreq maintainers. >> >> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com> >> --- >> MAINTAINERS | 1 + >> include/trace/events/devfreq.h | 39 +++++++++++++++++++++++++++++++++++++++ >> 2 files changed, 40 insertions(+) >> create mode 100644 include/trace/events/devfreq.h >> >> diff --git a/MAINTAINERS b/MAINTAINERS >> index 9919840..c042fda 100644 >> --- a/MAINTAINERS >> +++ b/MAINTAINERS >> @@ -4447,6 +4447,7 @@ S: Maintained >> F: drivers/devfreq/ >> F: include/linux/devfreq.h >> F: Documentation/devicetree/bindings/devfreq/ >> +F: include/trace/events/devfreq.h >> >> DEVICE FREQUENCY EVENT (DEVFREQ-EVENT) >> M: Chanwoo Choi <cw00.choi@samsung.com> >> diff --git a/include/trace/events/devfreq.h b/include/trace/events/devfreq.h >> new file mode 100644 >> index 0000000..fec9304 >> --- /dev/null >> +++ b/include/trace/events/devfreq.h >> @@ -0,0 +1,39 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +#undef TRACE_SYSTEM >> +#define TRACE_SYSTEM devfreq >> + >> +#if !defined(_TRACE_DEVFREQ_H) || defined(TRACE_HEADER_MULTI_READ) >> +#define _TRACE_DEVFREQ_H >> + >> +#include <linux/devfreq.h> >> +#include <linux/tracepoint.h> >> + >> +TRACE_EVENT(devfreq_monitor, >> + TP_PROTO(const char *dev_name, unsigned long freq, >> + unsigned int polling_ms, unsigned long busy_time, >> + unsigned long total_time), >> + >> + TP_ARGS(dev_name, freq, polling_ms, busy_time, total_time), >> + >> + TP_STRUCT__entry( >> + __string(dev_name, dev_name) >> + __field(unsigned long, freq) >> + __field(unsigned int, polling_ms) >> + __field(unsigned int, load) >> + ), >> + >> + TP_fast_assign( >> + __assign_str(dev_name, dev_name); >> + __entry->freq = freq; >> + __entry->polling_ms = polling_ms; >> + __entry->load = (100 * busy_time) / total_time; > > How critical is the code that this trace event is called in. If it is > not that critical (it is a slow path), then this is fine, but if this > is not a slow path (something triggered 100 HZ or less), then I would > recommend moving the above calculation to TP_printk(). A divide is a > slow operation, and is best to do that in the post processing. The > current location does the divide at the time of the tracepoint is > called. I wasn't aware of these two stages, good to know. I will move it to TP_printk(). > > I would also have a check to make sure that total_time is not zero > here, otherwise that could be bad. > > __entry->busy_time = busy_time; > __entry->total_time = total_time; >
>> + ), >> + >> + TP_printk("dev_name=%s freq=%lu polling_ms=%u load=%u", > > >> + __get_str(dev_name), __entry->freq, __entry->polling_ms, > > __entry->total_time == 0 ? 100 : > __entry->busy_time / __entry->total_time) Thank you for the review. I will add this check.
Regards, Lukasz > > -- Steve > >> + __entry->load) >> +); >> +#endif /* _TRACE_DEVFREQ_H */ >> + >> +/* This part must be outside protection */ >> +#include <trace/define_trace.h> > > >
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