Messages in this thread Patch in this message | | | From | Arnaldo Carvalho de Melo <> | Date | Thu, 6 Jun 2019 17:08:26 -0300 | Subject | Re: [PATCH V3 2/5] perf header: Add die information in CPU topology |
| |
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.
- 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:
| |