[RFC] perf tools: Add hugetlbfs memory recognition

Hou Pengyang
2015-06-27T08:50:01Z

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@huawei.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