perf tools powerpc: Cache the DWARF debug info

Cache the DWARF debug info for DSO so we don't have to rebuild it for each
address in the DSO.

Note that dso__new() uses calloc() so don't need to set dso->dwfl to NULL.

	$ /tmp/perf.orig --version
	perf version 3.18.rc1.gc2661b8
	$ /tmp/perf.new --version
	perf version 3.18.rc1.g402d62
	$ perf stat -e cycles,instructions /tmp/perf.orig report -g > orig

	 Performance counter stats for '/tmp/perf.orig report -g':

	     6,428,177,183 cycles                    #    0.000 GHz
	     4,176,288,391 instructions              #    0.65  insns per cycle

	       1.840666132 seconds time elapsed

	$ perf stat -e cycles,instructions /tmp/perf.new report -g > new

	 Performance counter stats for '/tmp/perf.new report -g':

	       305,773,142 cycles                    #    0.000 GHz
	       276,048,272 instructions              #    0.90  insns per cycle

	       0.087693543 seconds time elapsed
	$ diff orig new
	$

Changelog[v2]:

[Arnaldo Carvalho] Cache in existing global objects rather than create
                   new static/globals in functions.

Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Anton Blanchard <anton@au1.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20141022000958.GB2228@us.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/arch/powerpc/util/skip-callchain-idx.c b/tools/perf/arch/powerpc/util/skip-callchain-idx.c
index d73ef8b..9892b0f 100644 (file)
--- a/tools/perf/arch/powerpc/util/skip-callchain-idx.c
+++ b/tools/perf/arch/powerpc/util/skip-callchain-idx.c
@@ -145,7 +145,7 @@ static Dwarf_Frame *get_dwarf_frame(Dwfl_Module *mod, Dwarf_Addr pc)
  *             yet used)
  *     -1 in case of errors
  */
-static int check_return_addr(const char *exec_file, Dwarf_Addr pc)
+static int check_return_addr(struct dso *dso, Dwarf_Addr pc)
 {
        int             rc = -1;
        Dwfl            *dwfl;
@@ -156,15 +156,27 @@ static int check_return_addr(const char *exec_file, Dwarf_Addr pc)
        Dwarf_Addr      end = pc;
        bool            signalp;
 
-       dwfl = dwfl_begin(&offline_callbacks);
-       if (!dwfl) {
-               pr_debug("dwfl_begin() failed: %s\n", dwarf_errmsg(-1));
-               return -1;
-       }
+       dwfl = dso->dwfl;
 
-       if (dwfl_report_offline(dwfl, "",  exec_file, -1) == NULL) {
-               pr_debug("dwfl_report_offline() failed %s\n", dwarf_errmsg(-1));
-               goto out;
+       if (!dwfl) {
+               dwfl = dwfl_begin(&offline_callbacks);
+               if (!dwfl) {
+                       pr_debug("dwfl_begin() failed: %s\n", dwarf_errmsg(-1));
+                       return -1;
+               }
+
+               if (dwfl_report_offline(dwfl, "", dso->long_name, -1) == NULL) {
+                       pr_debug("dwfl_report_offline() failed %s\n",
+                                               dwarf_errmsg(-1));
+                       /*
+                        * We normally cache the DWARF debug info and never
+                        * call dwfl_end(). But to prevent fd leak, free in
+                        * case of error.
+                        */
+                       dwfl_end(dwfl);
+                       goto out;
+               }
+               dso->dwfl = dwfl;
        }
 
        mod = dwfl_addrmodule(dwfl, pc);
@@ -194,7 +206,6 @@ static int check_return_addr(const char *exec_file, Dwarf_Addr pc)
        rc = check_return_reg(ra_regno, frame);
 
 out:
-       dwfl_end(dwfl);
        return rc;
 }
 
@@ -246,7 +257,7 @@ int arch_skip_callchain_idx(struct machine *machine, struct thread *thread,
                return skip_slot;
        }
 
-       rc = check_return_addr(dso->long_name, ip);
+       rc = check_return_addr(dso, ip);
 
        pr_debug("DSO %s, nr %" PRIx64 ", ip 0x%" PRIx64 "rc %d\n",
                                dso->long_name, chain->nr, ip, rc);

diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index acb651a..3c9b391 100644 (file)
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -127,6 +127,7 @@ struct dso {
        const char       *long_name;
        u16              long_name_len;
        u16              short_name_len;
+       void            *dwfl;                  /* DWARF debug info */
 
        /* dso data file */
        struct {