linux-kernel - Re: [PATCH v1 1/6] perf record: Record the first sample time and last sample time to perf file header

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Date:   Thu, 21 Sep 2017 17:21:10 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Jin Yao <yao.jin@...ux.intel.com>
Cc:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH v1 1/6] perf record: Record the first sample time and
 last sample time to perf file header

On Thu, Sep 21, 2017 at 05:18:42PM +0200, Jiri Olsa wrote:
> On Wed, Sep 20, 2017 at 11:12:32PM +0800, Jin Yao wrote:
> 
> SNIP
> 
> > @@ -2647,11 +2681,22 @@ int perf_file_header__read(struct perf_file_header *header,
> >  
> >  	if (header->size != sizeof(*header)) {
> >  		/* Support the previous format */
> > -		if (header->size == offsetof(typeof(*header), adds_features))
> > +		if (header->size == offsetof(typeof(*header), adds_features)) {
> >  			bitmap_zero(header->adds_features, HEADER_FEAT_BITS);
> > -		else
> > +			header->first_sample_time = 0;
> > +			header->last_sample_time = 0;
> > +			format_feature = false;
> > +			format_time = false;
> > +		} else if (header->size == offsetof(typeof(*header),
> > +				first_sample_time)) {
> > +			header->first_sample_time = 0;
> > +			header->last_sample_time = 0;
> > +			format_time = false;
> > +		} else
> 
> ok, disregard my previou comment.. I should have read the full patch first ;-)

still using the feature looks better to me.. I think we could
add some generic TLV data feature for cases like this

jirka