lkml.org 
[lkml]   [2011]   [Mar]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] perf probe: Add fastpath to do lookup by function name
Date
The vmlinux file may have thousands of CUs.
We can lookup function name from .debug_pubnames section
to avoid the slow loop on CUs.

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
---
tools/perf/util/probe-finder.c | 38 ++++++++++++++++++++++++++++++++++++++
tools/perf/util/probe-finder.h | 1 +
2 files changed, 39 insertions(+), 0 deletions(-)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 194f9e2..b2034c2 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1876,6 +1876,30 @@ static int find_line_range_by_func(struct line_finder *lf)
return param.retval;
}

+static int pubname_search_cb(Dwarf *dbg, Dwarf_Global *gl, void *data)
+{
+ struct line_finder *lf = data;
+ struct line_range *lr = lf->lr;
+
+ if (dwarf_offdie(dbg, gl->die_offset, &lf->sp_die)) {
+ if (dwarf_tag(&lf->sp_die) != DW_TAG_subprogram)
+ return DWARF_CB_OK;
+
+ if (die_compare_name(&lf->sp_die, lr->function)) {
+ if (!dwarf_offdie(dbg, gl->cu_offset, &lf->cu_die))
+ return DWARF_CB_OK;
+
+ if (lr->file && !cu_find_realpath(&lf->cu_die, lr->file))
+ return DWARF_CB_OK;
+
+ lf->found = 1;
+ return DWARF_CB_ABORT;
+ }
+ }
+
+ return DWARF_CB_OK;
+}
+
int find_line_range(int fd, struct line_range *lr)
{
struct line_finder lf = {.lr = lr, .found = 0};
@@ -1895,6 +1919,19 @@ int find_line_range(int fd, struct line_range *lr)
return -EBADF;
}

+ /* Fastpath: lookup by function name from .debug_pubnames section */
+ if (lr->function) {
+ struct dwarf_callback_param param = {.data = (void *)&lf, .retval = 0};
+
+ dwarf_getpubnames(dbg, pubname_search_cb, &lf, 0);
+ if (lf.found) {
+ lf.found = 0;
+ line_range_search_cb(&lf.sp_die, &param);
+ if (lf.found)
+ goto found;
+ }
+ }
+
/* Loop on CUs (Compilation Unit) */
while (!lf.found && ret >= 0) {
if (dwarf_nextcu(dbg, off, &noff, &cuhl, NULL, NULL, NULL) != 0)
@@ -1923,6 +1960,7 @@ int find_line_range(int fd, struct line_range *lr)
off = noff;
}

+found:
/* Store comp_dir */
if (lf.found) {
comp_dir = cu_get_comp_dir(&lf.cu_die);
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
index beaefc3..4bc56a4 100644
--- a/tools/perf/util/probe-finder.h
+++ b/tools/perf/util/probe-finder.h
@@ -83,6 +83,7 @@ struct line_finder {
int lno_s; /* Start line number */
int lno_e; /* End line number */
Dwarf_Die cu_die; /* Current CU */
+ Dwarf_Die sp_die;
int found;
};

--
1.7.2.3


\
 
 \ /
  Last update: 2011-03-24 08:45    [W:0.063 / U:1.076 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site