On Mon, Feb 02, 2015 at 11:52:26AM +0200, Adrian Hunter wrote: > On 02/02/15 11:15, Jiri Olsa wrote: > > On Mon, Feb 02, 2015 at 10:34:50AM +0200, Adrian Hunter wrote: > > > > SNIP > > > >>> but how about bump up the header version for this feature? ;-) > >>> > >>> currently it's: > >>> > >>> struct perf_file_header { > >>> u64 magic; > >>> u64 size; > >>> u64 attr_size; > >>> struct perf_file_section attrs; > >>> struct perf_file_section data; > >>> /* event_types is ignored */ > >>> struct perf_file_section event_types; > >>> DECLARE_BITMAP(adds_features, HEADER_FEAT_BITS); > >>> }; > >>> > >>> > >>> - we already store attrs as a FEATURE so we could omit that > >>> - your patch stores only synthesized data into 'data' section (-1 idx) > >>> this could be stored into separate file and get merged with the rest > >>> - new header version would have 'features' section, so the features > >>> position wouldnt depend on the 'data' end as of now and we could > >>> easily store after all data is merged: > >>> > >>> struct perf_file_header { > >>> u64 magic; > >>> u64 size; > >>> u64 attr_size; > >>> struct perf_file_section features; > >>> DECLARE_BITMAP(adds_features, HEADER_FEAT_BITS); > >>> }; > >>> > >>> > >>> thoughts? > >> > >> How come the features are being written before the sample data anyway? > >> I would have expected: > >> - write the data (update the index in memory) > >> - write the features (including index) > >> > > > > I think the problem is that the only way how to get features offset > > right now is via perf_file_header::data.offset + perf_file_headerdata.size, > > and we still use this section to carry 'sythesized' data, so it needs > > to have correct size. > > Why not make it the same as all the other data. i.e. find the start and size > via the index? And then just lump all the data together?
thats what I suggested > > > I guess we could workaround that by storing the 'perf_file_header::data' > > as the last data section. That would require to treat it the same way as > > all other data sections, but we could keep current header layout. > > Would it need to be last? Logically it should precede the data that depends > on it. i suggested this as a workaround for having features at the end of the file while keeping the current perf data header jirka -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/