linux-kernel - Re: [PATCH 5/5] platform/x86/intel/ifs: Trace support for array test

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Date:   Mon, 6 Feb 2023 11:40:53 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Jithu Joseph <jithu.joseph@...el.com>
Cc:     hdegoede@...hat.com, markgross@...nel.org, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, gregkh@...uxfoundation.org,
        ashok.raj@...el.com, tony.luck@...el.com,
        linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        patches@...ts.linux.dev, ravi.v.shankar@...el.com,
        thiago.macieira@...el.com, athenas.jimenez.gonzalez@...el.com,
        sohil.mehta@...el.com
Subject: Re: [PATCH 5/5] platform/x86/intel/ifs: Trace support for array
 test

On Tue, 31 Jan 2023 15:43:02 -0800
Jithu Joseph <jithu.joseph@...el.com> wrote:

> diff --git a/include/trace/events/intel_ifs.h b/include/trace/events/intel_ifs.h
> index d7353024016c..db43df4139a2 100644
> --- a/include/trace/events/intel_ifs.h
> +++ b/include/trace/events/intel_ifs.h
> @@ -35,6 +35,33 @@ TRACE_EVENT(ifs_status,
>  		__entry->status)
>  );
>  
> +TRACE_EVENT(ifs_array,
> +
> +	TP_PROTO(int cpu, union ifs_array activate, union ifs_array status),
> +
> +	TP_ARGS(cpu, activate, status),
> +
> +	TP_STRUCT__entry(
> +		__field(	u64,	status	)
> +		__field(	int,	cpu	)
> +		__field(	u32,	arrays	)
> +		__field(	u16,	bank	)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->cpu	= cpu;
> +		__entry->arrays	= activate.array_bitmask;
> +		__entry->bank	= activate.array_bank;

Regardless of the "bitfield" discussion on the other patches, this part
is considered a fast path (although if where it is called, then it may
not be). I would just have:

		__field(	u64,	data	)

		__entry->data = status.data;


> +		__entry->status	= status.data;
> +	),
> +
> +	TP_printk("cpu: %d, array_list: %.8x, array_bank: %.4x, status: %.16llx",
> +		__entry->cpu,

> +		__entry->arrays,
> +		__entry->bank,

		__entry->data >> 32,
		(__entry->data >> 16) & 0xffff,

Or something similar. That is, move the parsing of the bits to the
output. libtraceevent should still be able to handle this.

-- Steve

> +		__entry->status)
> +);
> +