linux-kernel - [RFC] perf tools: Add hugetlbfs memory recognition

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Date:	Sat, 27 Jun 2015 08:49:13 +0000
From:	Hou Pengyang <houpengyang@...wei.com>
To:	<acme@...nel.org>, <mingo@...hat.com>, <namhyung@...nel.org>,
	<a.p.zijlstra@...llo.nl>
CC:	<wangnan0@...wei.com>, <linux-kernel@...r.kernel.org>,
	<zhu.wen-jie@...com>
Subject: [RFC] perf tools: Add hugetlbfs memory recognition

Maps for JIT is helpful for symbols-parsing for anon-executable-memory.
What we need to do is to add (START, SIZE, symbolname) to /tmp/perf-%d.map
(%d = pid of process), and perf would parse symbol located in this area
according to /tmp/perf-%d.map. It works well for normal mmap.

However, when we alloc such memory from hugetlbfs by the following code:

......

    fd = open("/mnt/huge/hugepagefile", O_CREAT | O_RDWR, 0755);
    if (fd < 0) {
        perror("Open failed");
        exit(1);
    }   
    addr = mmap(ADDR, LENGTH, PROT_READ | PROT_WRITE |     \   
        PROT_EXEC, MAP_SHARED, fd, 0); 

......
where hugetlbfs is mounted in /mnt/huge. Symbols could not be parsed correctly:

#perf report
   86.96%     0.00%  hugepage-mmap  hugepagefile      [.] 0xffffffe00000005c      
   86.96%     0.00%  hugepage-mmap  hugepagefile      [.] 0xffffffe0000000ac

This is because such mmap area's file backed is "/mnt/huge/hugepagefile", a node 
in pseudo filesystem, it is useless for symbol-parsing. so wo had better recognize 
such hugetlbfs area, and rename it's filename to /tmp/perf-%d.map, just as anon-memory
and no_dso_memory do. 

This patch imports a new function named is_hugetlb_memory to check if this memory
is from hugetlbfs. If true, change its name.  

After this patch:
#perf report 
   86.96%     0.00%  hugepage-mmap  perf-182.map        [.] 0x000000200000005c 
   86.96%     0.00%  hugepage-mmap  perf-182.map        [.] 0x00000020000000ac

We can add maps info to perf-182.map for further symbols-parsing.

Signed-off-by: Hou Pengyang <houpengyang@...wei.com>
---
 tools/perf/util/map.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index b5a5e9c..796db08 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -15,6 +15,7 @@
 #include "debug.h"
 #include "machine.h"
 #include <linux/string.h>
+#include <sys/mman.h>
 
 static void __maps__insert(struct maps *maps, struct map *map);
 
@@ -43,6 +44,11 @@ static inline int is_android_lib(const char *filename)
 	       !strncmp(filename, "/system/lib", 11);
 }
 
+static inline int is_hugetlb_memory(u32 flags)
+{
+	return flags & MAP_HUGETLB;
+}
+
 static inline bool replace_android_lib(const char *filename, char *newfilename)
 {
 	const char *libname;
@@ -151,12 +157,13 @@ struct map *map__new(struct machine *machine, u64 start, u64 len,
 	if (map != NULL) {
 		char newfilename[PATH_MAX];
 		struct dso *dso;
-		int anon, no_dso, vdso, android;
+		int anon, no_dso, vdso, android, hugetlb;
 
 		android = is_android_lib(filename);
 		anon = is_anon_memory(filename);
 		vdso = is_vdso_map(filename);
 		no_dso = is_no_dso_memory(filename);
+		hugetlb = is_hugetlb_memory(flags);
 
 		map->maj = d_maj;
 		map->min = d_min;
@@ -165,7 +172,7 @@ struct map *map__new(struct machine *machine, u64 start, u64 len,
 		map->prot = prot;
 		map->flags = flags;
 
-		if ((anon || no_dso) && type == MAP__FUNCTION) {
+		if ((anon || no_dso || hugetlb) && type == MAP__FUNCTION) {
 			snprintf(newfilename, sizeof(newfilename), "/tmp/perf-%d.map", pid);
 			filename = newfilename;
 		}
-- 
1.8.3.4

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