Messages in this thread | | | Subject | Re: [PATCH V3 2/5] perf header: Add die information in CPU topology | From | "Liang, Kan" <> | Date | Thu, 6 Jun 2019 16:56:20 -0400 |
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On 6/6/2019 4:08 PM, Arnaldo Carvalho de Melo wrote: > Em Thu, Jun 06, 2019 at 04:12:10PM -0300, Arnaldo Carvalho de Melo escreveu: >> Em Tue, Jun 04, 2019 at 03:50:41PM -0700, kan.liang@linux.intel.com escreveu: >>> From: Kan Liang <kan.liang@linux.intel.com> >>> >>> With the new CPUID.1F, a new level type of CPU topology, 'die', is >>> introduced. The 'die' information in CPU topology should be added in >>> perf header. >>> >>> To be compatible with old perf.data, the patch checks the section size >>> before reading the die information. The new info is added at the end of >>> the cpu_topology section, the old perf tool ignores the extra data. >>> It never reads data crossing the section boundary. >>> >>> The new perf tool with the patch can be used on legacy kernel. Add a >>> new function has_die_topology() to check if die topology information is >>> supported by kernel. The function only check X86 and CPU 0. Assuming >>> other CPUs have same topology. >> >> You're changing the header, how would a new tool handle an old perf.data >> where this 'die_id' is not present? What about an old tool dealing with >> a perf.data with this die_id? >> >> I couldn't see any provision for that, am I missing something? >> >> /me goes to read tools/perf/util/cputopo.c ... >> >> Yeah, its just the description on the perf.data doc file that confused >> me, I'll clarify that after finishing reviewing/applying this patchkit. > > So I have this on top, please check. >
It looks good to me.
Thanks, Kan
> - Arnaldo > > commit a9396a70fc7101c108e1c91fa1771557bbbb57a1 > Author: Arnaldo Carvalho de Melo <acme@redhat.com> > Date: Thu Jun 6 17:03:18 2019 -0300 > > perf data: Fix perf.data documentation for HEADER_CPU_TOPOLOGY > > The 'die' info isn't in the same array as core and socket ids, and we > missed the 'dies' string list, that comes right after the 'core' + > 'socket' id variable length array, followed by the VLA for the dies. > > Cc: Adrian Hunter <adrian.hunter@intel.com> > Cc: Andi Kleen <ak@linux.intel.com> > Cc: Jiri Olsa <jolsa@kernel.org> > Cc: Kan Liang <kan.liang@linux.intel.com> > Cc: Namhyung Kim <namhyung@kernel.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Fixes: c9cb12c5ba08 ("perf header: Add die information in CPU topology") > Link: https://lkml.kernel.org/n/tip-nubi6mxp2n8ofvlx7ph6k3h6@git.kernel.org > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> > > diff --git a/tools/perf/Documentation/perf.data-file-format.txt b/tools/perf/Documentation/perf.data-file-format.txt > index de78183f6881..5f54feb19977 100644 > --- a/tools/perf/Documentation/perf.data-file-format.txt > +++ b/tools/perf/Documentation/perf.data-file-format.txt > @@ -151,20 +151,35 @@ struct { > > HEADER_CPU_TOPOLOGY = 13, > > -String lists defining the core and CPU threads topology. > -The string lists are followed by a variable length array > -which contains core_id, die_id (for x86) and socket_id of each cpu. > -The number of entries can be determined by the size of the > -section minus the sizes of both string lists. > - > struct { > + /* > + * First revision of HEADER_CPU_TOPOLOGY > + * > + * See 'struct perf_header_string_list' definition earlier > + * in this file. > + */ > + > struct perf_header_string_list cores; /* Variable length */ > struct perf_header_string_list threads; /* Variable length */ > + > + /* > + * Second revision of HEADER_CPU_TOPOLOGY, older tools > + * will not consider what comes next > + */ > + > struct { > uint32_t core_id; > - uint32_t die_id; > uint32_t socket_id; > } cpus[nr]; /* Variable length records */ > + /* 'nr' comes from previously processed HEADER_NRCPUS's nr_cpu_avail */ > + > + /* > + * Third revision of HEADER_CPU_TOPOLOGY, older tools > + * will not consider what comes next > + */ > + > + struct perf_header_string_list dies; /* Variable length */ > + uint32_t die_id[nr_cpus_avail]; /* from previously processed HEADER_NR_CPUS, VLA */ > }; > > Example: >
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