>From 773a3608a0cd2daf02e244cb9ffbf5bb6a0e724e Mon Sep 17 00:00:00 2001
From: Sukadev Bhattiprolu <[email protected]>
Date: Tue, 21 Oct 2014 13:20:22 -0500
Subject: [PATCH 1/1] perf/powerpc: Cache DWARF debug info
Cache the DWARF debug info for DSO so we don't have to rebuild it for
each address in the DSO (duh!).
$ time /tmp/perf.orig report -g > /tmp/report.1
real 0m1.845s
user 0m0.963s
sys 0m0.879s
$ time /tmp/perf report -g > /tmp/report.2
real 0m0.089s
user 0m0.082s
sys 0m0.006s
$ diff /tmp/report.1 /tmp/report.2
$
Reported-by: Anton Blanchard <[email protected]>
Signed-off-by: Sukadev Bhattiprolu <[email protected]>
---
tools/perf/arch/powerpc/util/skip-callchain-idx.c | 91 ++++++++++++++++++++---
1 file changed, 82 insertions(+), 9 deletions(-)
diff --git a/tools/perf/arch/powerpc/util/skip-callchain-idx.c
b/tools/perf/arch/powerpc/util/skip-callchain-idx.c
index d73ef8b..bfe254d 100644
--- a/tools/perf/arch/powerpc/util/skip-callchain-idx.c
+++ b/tools/perf/arch/powerpc/util/skip-callchain-idx.c
@@ -38,6 +38,63 @@ static const Dwfl_Callbacks offline_callbacks = {
.section_address = dwfl_offline_section_address,
};
+struct list_head perf_dwfl_files;
+
+struct perf_dwfl_node {
+ struct list_head node;
+ char *exec_file;
+ Dwfl *dwfl;
+};
+
+static void perf_init_dwfl(void)
+{
+ static int dwfl_inited;
+
+ if (!dwfl_inited) {
+ dwfl_inited = 1;
+ INIT_LIST_HEAD(&perf_dwfl_files);
+ }
+}
+
+static Dwfl *perf_dwfl_find(const char *file_name)
+{
+ struct list_head *pos;
+ struct perf_dwfl_node *node;
+
+ perf_init_dwfl();
+
+ list_for_each(pos, &perf_dwfl_files) {
+ node = list_entry(pos, struct perf_dwfl_node, node);
+ if (!strcmp(node->exec_file, file_name))
+ return node->dwfl;
+ }
+
+ return NULL;
+}
+
+
+/*
+ * Return 1 if were able to cache the DWARF debug info. 0 otherwise.
+ */
+static int perf_dwfl_cache(const char *file_name, Dwfl *dwfl)
+{
+ struct perf_dwfl_node *dwfl_node;
+
+ dwfl_node = malloc(sizeof(struct perf_dwfl_node));
+
+ if (!dwfl_node) {
+ pr_debug("%s(): Unable to alloc memory\n", __func__);
+ return 0;
+ }
+ INIT_LIST_HEAD(&dwfl_node->node);
+ dwfl_node->dwfl = dwfl;
+ dwfl_node->exec_file = strdup(file_name);
+
+ list_add(&dwfl_node->node, &perf_dwfl_files);
+
+ return 1;
+}
+
/*
* Use the DWARF expression for the Call-frame-address and determine
@@ -155,16 +212,26 @@ static int check_return_addr(const char *exec_file,
Dwarf_Addr pc)
Dwarf_Addr start = pc;
Dwarf_Addr end = pc;
bool signalp;
+ int cached;
- dwfl = dwfl_begin(&offline_callbacks);
+ cached = 1;
+ dwfl = perf_dwfl_find(exec_file);
if (!dwfl) {
- pr_debug("dwfl_begin() failed: %s\n", dwarf_errmsg(-1));
- return -1;
- }
-
- if (dwfl_report_offline(dwfl, "", exec_file, -1) == NULL) {
- pr_debug("dwfl_report_offline() failed %s\n", dwarf_errmsg(-1));
- goto out;
+ dwfl = dwfl_begin(&offline_callbacks);
+ if (!dwfl) {
+ pr_debug("dwfl_begin() failed: %s\n", dwarf_errmsg(-1));
+ return -1;
+ }
+
+ if (dwfl_report_offline(dwfl, "", exec_file, -1) == NULL) {
+ pr_debug("dwfl_report_offline() failed %s\n",
+ dwarf_errmsg(-1));
+ goto out;
+ }
+ /*
+ * If we fail to alloc memory, we lose the benefit of caching
+ */
+ cached = perf_dwfl_cache(exec_file, dwfl);
}
mod = dwfl_addrmodule(dwfl, pc);
@@ -194,7 +261,13 @@ static int check_return_addr(const char *exec_file,
Dwarf_Addr pc)
rc = check_return_reg(ra_regno, frame);
out:
- dwfl_end(dwfl);
+ /*
+ * In the unlikely event that we were unable to cache the debug
+ * info, release it so we don't leak fds.
+ */
+ if (!cached)
+ dwfl_end(dwfl);
+
return rc;
}
--
1.8.4.2
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