linux-kernel - Re: [PATCH v4] bus: mhi: host: Add tracing support

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Message-ID: <311c74f4-82ba-9a8e-3351-d9c96a369ec5@quicinc.com>
Date:   Tue, 14 Nov 2023 10:05:04 +0530
From:   Krishna Chaitanya Chundru <quic_krichai@...cinc.com>
To:     Steven Rostedt <rostedt@...dmis.org>
CC:     Manivannan Sadhasivam <mani@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        <linux-kernel@...r.kernel.org>, <mhi@...ts.linux.dev>,
        <linux-arm-msm@...r.kernel.org>,
        <linux-trace-kernel@...r.kernel.org>, <quic_vbadigan@...cinc.com>,
        <quic_ramkri@...cinc.com>, <quic_nitegupt@...cinc.com>,
        <quic_skananth@...cinc.com>, <quic_parass@...cinc.com>
Subject: Re: [PATCH v4] bus: mhi: host: Add tracing support


On 11/12/2023 1:07 AM, Steven Rostedt wrote:
> On Sat, 11 Nov 2023 11:25:22 +0530
> Krishna chaitanya chundru <quic_krichai@...cinc.com> wrote:
>> diff --git a/drivers/bus/mhi/host/trace.h b/drivers/bus/mhi/host/trace.h
>> new file mode 100644
>> index 000000000000..0e99318f5d08
>> --- /dev/null
>> +++ b/drivers/bus/mhi/host/trace.h
>> +
>> +TRACE_EVENT(mhi_update_channel_state_start,
>> +
>> +	TP_PROTO(const char *name, int ch_num, int state),
>> +
>> +	TP_ARGS(name, ch_num, state),
>> +
>> +	TP_STRUCT__entry(
>> +		__string(name, name)
>> +		__field(int, ch_num)
>> +		__field(int, state)
>> +	),
>> +
>> +	TP_fast_assign(
>> +		__assign_str(name, name);
>> +		__entry->ch_num = ch_num;
>> +		__entry->state = state;
>> +	),
>> +
>> +	TP_printk("%s: ch%d: Updating state to: %s\n",
>> +		  __get_str(name), __entry->ch_num,
>> +		  TO_CH_STATE_TYPE_STR(__entry->state))
>> +);
>> +
>> +TRACE_EVENT(mhi_update_channel_state_end,
>> +
>> +	TP_PROTO(const char *name, int ch_num, int state),
>> +
>> +	TP_ARGS(name, ch_num, state),
>> +
>> +	TP_STRUCT__entry(
>> +		__string(name, name)
>> +		__field(int, ch_num)
>> +		__field(int, state)
>> +	),
>> +
>> +	TP_fast_assign(
>> +		__assign_str(name, name);
>> +		__entry->ch_num = ch_num;
>> +		__entry->state = state;
>> +	),
>> +
>> +	TP_printk("%s: ch%d: Updated state to: %s\n",
>> +		  __get_str(name), __entry->ch_num,
>> +		  TO_CH_STATE_TYPE_STR(__entry->state))
>> +);
>> +
> The above three events have the same format. You can save kilobytes of
> memory by converting them into a DECLARE_EVENT_CLASS() and use
> DEFINE_EVENT() for each event.
>
> A TRACE_EVENT() macro is really just a wrapper around
> DECLARE_EVENT_CLASS() and DEFINE_EVENT(). The DECLARE_EVENT_CLASS()
> does the bulk of the work and adds the most memory footprint. By
> breaking it apart for several events, it does save memory.
>
> Whenever you can use a single DECLARE_EVENT_CLASS() for multiple
> events, I strongly suggest doing so.
>
> Thanks,
>
> -- Steve

Sure steve I will change as suggested in my next patch.

- Krishna Chaitanya.

>
>> +#endif
>> +#undef TRACE_INCLUDE_PATH
>> +#define TRACE_INCLUDE_PATH .
>> +#undef TRACE_INCLUDE_FILE
>> +#define TRACE_INCLUDE_FILE trace
>> +
>> +#include <trace/define_trace.h>
>>
>> ---
>> base-commit: 3006adf3be79cde4d14b1800b963b82b6e5572e0
>> change-id: 20231005-ftrace_support-6869d4156139
>>
>> Best regards,