perf record: Introduce a symtab cache

Now a cache will be created in a ~/.debug debuginfo like
hierarchy, so that at the end of a 'perf record' session all the
binaries (with build-ids) involved get collected and indexed by
their build-ids, so that perf report can find them.

This is interesting when developing software where you want to
do a 'perf diff' with the previous build and opens avenues for
lots more interesting tools, like a 'perf diff --graph' that
takes more than two binaries into account.

Tunables for collecting just the symtabs can be added if one
doesn't want to have the full binary, but having the full binary
allows things like 'perf rerecord' or other tools that can
re-run the tests by having access to the exact binary in some
perf.data file, so it may well be interesting to keep the full
binary there.

Space consumption is minimised by trying to use hard links, a
'perf cache' tool to manage the space used, a la ccache is
required to purge older entries.

With this in place it will be possible also to introduce new
commands, 'perf archive' and 'perf restore' (or some more
suitable and future proof names) to create a cpio/tar file with
the perf data and the files in the cache that _had_ perf hits of
interest.

There are more aspects to polish, like finding the right vmlinux
file to cache, etc, but this is enough for a first step.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1261957026-15580-10-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index fafea0b6f323ec8709a4e50410167da4415dc0d3..7c846424aebf933673c51a729671246a9bdf0ebd 100644 (file)
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -425,6 +425,7 @@ LIB_OBJS += util/svghelper.o
 LIB_OBJS += util/sort.o
 LIB_OBJS += util/hist.o
 LIB_OBJS += util/probe-event.o
+LIB_OBJS += util/util.o
 
 BUILTIN_OBJS += builtin-annotate.o
 

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 8a0bca55106f8d4ddb15492404367ef5b3f3de88..df237c3a041b6b64fee96a8b52f11e6d56ba21b3 100644 (file)
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -169,20 +169,23 @@ static int do_write(int fd, const void *buf, size_t size)
        return 0;
 }
 
+#define dsos__for_each_with_build_id(pos, head)        \
+       list_for_each_entry(pos, head, node)    \
+               if (!pos->has_build_id)         \
+                       continue;               \
+               else
+
 static int __dsos__write_buildid_table(struct list_head *head, int fd)
 {
 #define NAME_ALIGN     64
        struct dso *pos;
        static const char zero_buf[NAME_ALIGN];
 
-       list_for_each_entry(pos, head, node) {
+       dsos__for_each_with_build_id(pos, head) {
                int err;
                struct build_id_event b;
-               size_t len;
+               size_t len = pos->long_name_len + 1;
 
-               if (!pos->has_build_id)
-                       continue;
-               len = pos->long_name_len + 1;
                len = ALIGN(len, NAME_ALIGN);
                memset(&b, 0, sizeof(b));
                memcpy(&b.build_id, pos->build_id, sizeof(pos->build_id));
@@ -209,6 +212,74 @@ static int dsos__write_buildid_table(int fd)
        return err;
 }
 
+static int dso__cache_build_id(struct dso *self, const char *debugdir)
+{
+       const size_t size = PATH_MAX;
+       char *filename = malloc(size),
+            *linkname = malloc(size), *targetname, *sbuild_id;
+       int len, err = -1;
+
+       if (filename == NULL || linkname == NULL)
+               goto out_free;
+
+       len = snprintf(filename, size, "%s%s", debugdir, self->long_name);
+       if (mkdir_p(filename, 0755))
+               goto out_free;
+
+       len += snprintf(filename + len, sizeof(filename) - len, "/");
+       sbuild_id = filename + len;
+       build_id__sprintf(self->build_id, sizeof(self->build_id), sbuild_id);
+
+       if (access(filename, F_OK) && link(self->long_name, filename) &&
+           copyfile(self->long_name, filename))
+               goto out_free;
+
+       len = snprintf(linkname, size, "%s/.build-id/%.2s",
+                      debugdir, sbuild_id);
+
+       if (access(linkname, X_OK) && mkdir_p(linkname, 0755))
+               goto out_free;
+
+       snprintf(linkname + len, size - len, "/%s", sbuild_id + 2);
+       targetname = filename + strlen(debugdir) - 5;
+       memcpy(targetname, "../..", 5);
+
+       if (symlink(targetname, linkname) == 0)
+               err = 0;
+out_free:
+       free(filename);
+       free(linkname);
+       return err;
+}
+
+static int __dsos__cache_build_ids(struct list_head *head, const char *debugdir)
+{
+       struct dso *pos;
+       int err = 0;
+
+       dsos__for_each_with_build_id(pos, head)
+               if (dso__cache_build_id(pos, debugdir))
+                       err = -1;
+
+       return err;
+}
+
+static int dsos__cache_build_ids(void)
+{
+       int err_kernel, err_user;
+       char debugdir[PATH_MAX];
+
+       snprintf(debugdir, sizeof(debugdir), "%s/%s", getenv("HOME"),
+                DEBUG_CACHE_DIR);
+
+       if (mkdir(debugdir, 0755) != 0 && errno != EEXIST)
+               return -1;
+
+       err_kernel = __dsos__cache_build_ids(&dsos__kernel, debugdir);
+       err_user   = __dsos__cache_build_ids(&dsos__user, debugdir);
+       return err_kernel || err_user ? -1 : 0;
+}
+
 static int perf_header__adds_write(struct perf_header *self, int fd)
 {
        int nr_sections;
@@ -258,6 +329,7 @@ static int perf_header__adds_write(struct perf_header *self, int fd)
                        goto out_free;
                }
                buildid_sec->size = lseek(fd, 0, SEEK_CUR) - buildid_sec->offset;
+               dsos__cache_build_ids();
        }
 
        lseek(fd, sec_start, SEEK_SET);

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index ab92763edb03f757e2941f95040133f96f84da02..79ca6a099f96a70447ba81d5973d121a761ad983 100644 (file)
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -22,6 +22,7 @@
 enum dso_origin {
        DSO__ORIG_KERNEL = 0,
        DSO__ORIG_JAVA_JIT,
+       DSO__ORIG_BUILD_ID_CACHE,
        DSO__ORIG_FEDORA,
        DSO__ORIG_UBUNTU,
        DSO__ORIG_BUILDID,
@@ -1191,6 +1192,7 @@ char dso__symtab_origin(const struct dso *self)
        static const char origin[] = {
                [DSO__ORIG_KERNEL] =   'k',
                [DSO__ORIG_JAVA_JIT] = 'j',
+               [DSO__ORIG_BUILD_ID_CACHE] = 'B',
                [DSO__ORIG_FEDORA] =   'f',
                [DSO__ORIG_UBUNTU] =   'u',
                [DSO__ORIG_BUILDID] =  'b',
@@ -1209,6 +1211,7 @@ int dso__load(struct dso *self, struct map *map, struct perf_session *session,
        int size = PATH_MAX;
        char *name;
        u8 build_id[BUILD_ID_SIZE];
+       char build_id_hex[BUILD_ID_SIZE * 2 + 1];
        int ret = -1;
        int fd;
 
@@ -1230,8 +1233,16 @@ int dso__load(struct dso *self, struct map *map, struct perf_session *session,
                return ret;
        }
 
-       self->origin = DSO__ORIG_FEDORA - 1;
+       self->origin = DSO__ORIG_BUILD_ID_CACHE;
 
+       if (self->has_build_id) {
+               build_id__sprintf(self->build_id, sizeof(self->build_id),
+                                 build_id_hex);
+               snprintf(name, size, "%s/%s/.build-id/%.2s/%s",
+                        getenv("HOME"), DEBUG_CACHE_DIR,
+                        build_id_hex, build_id_hex + 2);
+               goto open_file;
+       }
 more:
        do {
                self->origin++;
@@ -1247,8 +1258,6 @@ more:
                case DSO__ORIG_BUILDID:
                        if (filename__read_build_id(self->long_name, build_id,
                                                    sizeof(build_id))) {
-                               char build_id_hex[BUILD_ID_SIZE * 2 + 1];
-
                                build_id__sprintf(build_id, sizeof(build_id),
                                                  build_id_hex);
                                snprintf(name, size,
@@ -1276,7 +1285,7 @@ compare_build_id:
                        if (!dso__build_id_equal(self, build_id))
                                goto more;
                }
-
+open_file:
                fd = open(name, O_RDONLY);
        } while (fd < 0);
 

diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 9eabd60f819d0150830c35efda3339fcc4bf1c14..f27e158943e9b5f6d12b609741a96b961afd47be 100644 (file)
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -8,6 +8,8 @@
 #include <linux/rbtree.h>
 #include "event.h"
 
+#define DEBUG_CACHE_DIR ".debug"
+
 #ifdef HAVE_CPLUS_DEMANGLE
 extern char *cplus_demangle(const char *, int);
 

diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
new file mode 100644 (file)
index 0000000..f3c0798
--- /dev/null
+++ b/tools/perf/util/util.c
@@ -0,0 +1,69 @@
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+#include "util.h"
+
+int mkdir_p(char *path, mode_t mode)
+{
+       struct stat st;
+       int err;
+       char *d = path;
+
+       if (*d != '/')
+               return -1;
+
+       if (stat(path, &st) == 0)
+               return 0;
+
+       while (*++d == '/');
+
+       while ((d = strchr(d, '/'))) {
+               *d = '\0';
+               err = stat(path, &st) && mkdir(path, mode);
+               *d++ = '/';
+               if (err)
+                       return -1;
+               while (*d == '/')
+                       ++d;
+       }
+       return (stat(path, &st) && mkdir(path, mode)) ? -1 : 0;
+}
+
+int copyfile(const char *from, const char *to)
+{
+       int fromfd, tofd;
+       struct stat st;
+       void *addr;
+       int err = -1;
+
+       if (stat(from, &st))
+               goto out;
+
+       fromfd = open(from, O_RDONLY);
+       if (fromfd < 0)
+               goto out;
+
+       tofd = creat(to, 0755);
+       if (tofd < 0)
+               goto out_close_from;
+
+       addr = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fromfd, 0);
+       if (addr == MAP_FAILED)
+               goto out_close_to;
+
+       if (write(tofd, addr, st.st_size) == st.st_size)
+               err = 0;
+
+       munmap(addr, st.st_size);
+out_close_to:
+       close(tofd);
+       if (err)
+               unlink(to);
+out_close_from:
+       close(fromfd);
+out:
+       return err;
+}

diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index c673d8825883ce2bec91b03f5c1e474a756fde19..0f5b2a6f1080f6cd6a75f265ea2aa20787fc98e2 100644 (file)
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -403,4 +403,7 @@ void git_qsort(void *base, size_t nmemb, size_t size,
 #endif
 #endif
 
+int mkdir_p(char *path, mode_t mode);
+int copyfile(const char *from, const char *to);
+
 #endif