Messages in this thread | | | Date | Mon, 29 Sep 2014 10:34:52 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH v2 1/2] perf callchain: Create an address space per thread |
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On Mon, Sep 29, 2014 at 01:58:11PM +0900, Namhyung Kim wrote: > The unw_addr_space_t in libunwind represents an address space to be > used for stack unwinding. It doesn't need to be create/destory > everytime to unwind callchain (as in get_entries) and can have a same > lifetime as thread (unless exec called). > > So move the address space construction/destruction logic to the thread > lifetime handling functions. This is a preparation to enable caching > in the unwind library. > > Note that it saves unw_addr_space_t object using thread__set_priv(). > It seems currently only used by perf trace and perf kvm stat commands > which don't use callchain. > > Acked-by: Jean Pihet <jean.pihet@linaro.org> > Cc: Jiri Olsa <jolsa@redhat.com> > Cc: Arun Sharma <asharma@fb.com> > Cc: David Ahern <dsahern@gmail.com> > Cc: Frederic Weisbecker <fweisbec@gmail.com> > Signed-off-by: Namhyung Kim <namhyung@kernel.org> > --- > tools/perf/util/thread.c | 6 ++++++ > tools/perf/util/unwind-libunwind.c | 30 +++++++++++++++++++++++++----- > tools/perf/util/unwind.h | 17 +++++++++++++++++ > 3 files changed, 48 insertions(+), 5 deletions(-) > > diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c > index a9df7f2c6dc9..2b7b2d91c016 100644 > --- a/tools/perf/util/thread.c > +++ b/tools/perf/util/thread.c > @@ -7,6 +7,7 @@ > #include "util.h" > #include "debug.h" > #include "comm.h" > +#include "unwind.h" > > int thread__init_map_groups(struct thread *thread, struct machine *machine) > { > @@ -37,6 +38,9 @@ struct thread *thread__new(pid_t pid, pid_t tid) > thread->cpu = -1; > INIT_LIST_HEAD(&thread->comm_list); > > + if (unwind__prepare_access(thread) < 0) > + goto err_thread;
So this is something we need to do only for DWARF unwind via libunwind. Do we want some condition to bypass this in for the rest of the cases?
I think we could check for symbol_conf.use_callchain and for the PERF_SAMPLE_REGS_USER|PERF_SAMPLE_STACK_USER sample types in evlist, something like:
bool has_dwarf_data_for_callchains = symbol_conf.use_callchain && evlist_sample_type_has(evlist, PERF_SAMPLE_REGS_USER|PERF_SAMPLE_STACK_USER)
;-)
thanks, jirka
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