linux-kernel - Re: [BUG] perf report/annotate: consuming too many file descriptors

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Date:	Fri, 14 Feb 2014 16:11:28 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Jiri Olsa <jolsa@...hat.com>, David Ahern <dsahern@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"mingo\@elte.hu" <mingo@...e.hu>
Subject: Re: [BUG] perf report/annotate: consuming too many file descriptors

Hi Stephane,

On Thu, 13 Feb 2014 17:26:30 +0100, Stephane Eranian wrote:
> Hi,
>
> Your patch does solve the file consumption problem on my test case.
> We still open and do the ELF read 5 times.
>>> The first problem is why is dso__read_binary_type_filename()
>>> blindly returning success on many types. For my files, I got matches
>>> on DEBUGLINK, SYSTEM_DSO_PATH, GUEST_KMODULE,
>>> SYSTEM_PATH_KMODULE.

Hmm.. the dso__read_binary_type_filename() will be called for either of
user binaries or kernel modules.  But for each binary, it's pointless to
check both types of symtab since it can only have one type.

So I think we should try SYMTEM_PATH_DSO, DEBUGLINK, BUILD_ID_CACHE and
a couple of DEBUGINFOs for user binaries, and only try *_KMODULE for
kernel modules.  This way, we can reduce the unnecessary open and ELF
reading/parsing time.

Could you please test following patch also?


diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index a9d758a3b371..303b8dc59dd8 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1251,6 +1251,46 @@ out_failure:
 	return -1;
 }
 
+static bool dso__is_compatible_symtab_type(struct dso *dso, bool kmod,
+					   enum dso_binary_type type)
+{
+	switch (type) {
+	case DSO_BINARY_TYPE__JAVA_JIT:
+	case DSO_BINARY_TYPE__DEBUGLINK:
+	case DSO_BINARY_TYPE__SYSTEM_PATH_DSO:
+	case DSO_BINARY_TYPE__FEDORA_DEBUGINFO:
+	case DSO_BINARY_TYPE__UBUNTU_DEBUGINFO:
+	case DSO_BINARY_TYPE__BUILDID_DEBUGINFO:
+	case DSO_BINARY_TYPE__OPENEMBEDDED_DEBUGINFO:
+		return !kmod && dso->kernel == DSO_TYPE_USER;
+
+	case DSO_BINARY_TYPE__KALLSYMS:
+	case DSO_BINARY_TYPE__VMLINUX:
+	case DSO_BINARY_TYPE__KCORE:
+		return dso->kernel == DSO_TYPE_KERNEL;
+
+	case DSO_BINARY_TYPE__GUEST_KALLSYMS:
+	case DSO_BINARY_TYPE__GUEST_VMLINUX:
+	case DSO_BINARY_TYPE__GUEST_KCORE:
+		return dso->kernel == DSO_TYPE_GUEST_KERNEL;
+
+	case DSO_BINARY_TYPE__GUEST_KMODULE:
+	case DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE:
+		/*
+		 * kernel modules know their symtab type - it's set when
+		 * creating a module dso in machine__new_module().
+		 */
+		return kmod && dso->symtab_type == type;
+
+	case DSO_BINARY_TYPE__BUILD_ID_CACHE:
+		return true;
+
+	case DSO_BINARY_TYPE__NOT_FOUND:
+	default:
+		return false;
+	}
+}
+
 int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
 {
 	char *name;
@@ -1261,6 +1301,7 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
 	int ss_pos = 0;
 	struct symsrc ss_[2];
 	struct symsrc *syms_ss = NULL, *runtime_ss = NULL;
+	bool kmod;
 
 	dso__set_loaded(dso, map->type);
 
@@ -1301,7 +1342,11 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
 	if (!name)
 		return -1;
 
-	/* Iterate over candidate debug images.
+	kmod = dso->symtab_type == DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE ||
+		dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE;
+
+	/*
+	 * Iterate over candidate debug images.
 	 * Keep track of "interesting" ones (those which have a symtab, dynsym,
 	 * and/or opd section) for processing.
 	 */
@@ -1311,6 +1356,9 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
 
 		enum dso_binary_type symtab_type = binary_type_symtab[i];
 
+		if (!dso__is_compatible_symtab_type(dso, kmod, symtab_type))
+			continue;
+
 		if (dso__read_binary_type_filename(dso, symtab_type,
 						   root_dir, name, PATH_MAX))
 			continue;
@@ -1351,15 +1399,10 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
 	if (!runtime_ss && syms_ss)
 		runtime_ss = syms_ss;
 
-	if (syms_ss) {
-		int km;
-
-		km = dso->symtab_type == DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE ||
-		     dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE;
-		ret = dso__load_sym(dso, map, syms_ss, runtime_ss, filter, km);
-	} else {
+	if (syms_ss)
+		ret = dso__load_sym(dso, map, syms_ss, runtime_ss, filter, kmod);
+	else
 		ret = -1;
-	}
 
 	if (ret > 0) {
 		int nr_plt;
--
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