On 04/26/2016 02:34 PM, Masami Hiramatsu wrote:
From: Masami Hiramatsu <masami.hiramatsu...@hitachi.com>
perf buildid-cache --add <binary> scans given binary and add
the SDT events to probe cache. "sdt_" prefix is appended for
all SDT providers to avoid event-name clash with other pre-defined
events. It is possible to use the cached SDT events as other cached
events, via perf probe --add "sdt_<provider>:<event>=<event>".
e.g.
----
# perf buildid-cache --add /lib/libc-2.17.so
# perf probe --cache --list | head -n 5
/usr/lib/libc-2.17.so (a6fb821bdf53660eb2c29f778757aef294d3d392):
sdt_libc:setjmp=setjmp
sdt_libc:longjmp=longjmp
sdt_libc:longjmp_target=longjmp_target
sdt_libc:memory_heap_new=memory_heap_new
# perf probe -x /usr/lib/libc-2.17.so \
-a sdt_libc:memory_heap_new=memory_heap_new
Added new event:
sdt_libc:memory_heap_new (on memory_heap_new
in /usr/lib/libc-2.17.so)
You can now use it in all perf tools, such as:
perf record -e sdt_libc:memory_heap_new -aR sleep 1
# perf probe -l
sdt_libc:memory_heap_new (on new_heap+183 in /usr/lib/libc-2.17.so)
----
Patch looks good to me. Have a few questions below :
What about the same binary path having different build-ids. For e.g
a binary say, "test" has some markers, we add it to the cache. And,
then the file gets rebuilt again with different build-id now. And we try
to add to the cache again. It shows multiple entries in the cache :
# perf probe --cache --list
/home/hemant/test (157380727e2b3854395aa915dfc91dbccc02058b):
sdt_user_test:marker1=marker1
/home/hemant/test (64c0a018636e6d5145b09fc65839c1a4a7899f18):
sdt_user_test:marker1=marker1
/home/hemant/test (c9e34759ae95b68fa385831041c5d9e0dd1697fb):
sdt_user_test:marker1=marker1
...
But, perf list sdt shows only one entry (which it should) :
# perf list sdt
List of pre-defined events (to be used in -e):
sdt_user_test:marker1 [SDT event]
perf probe also works as expected :
# perf probe -x /home/hemant/test %sdt_user_test:marker1
Added new event:
sdt_user_test:marker1 (on %marker1 in /home/hemant/test)
You can now use it in all perf tools, such as:
perf record -e sdt_user_test:marker1 -aR sleep 1
So, the question is, do we delete the previous entries for "test" from
the cache once we get a newer version of "test"?
Note that SDT event entries in probe-cache file is somewhat different
from normal cached events. Normal one starts with "#", but SDTs are
starting with "%".
Signed-off-by: Masami Hiramatsu <masami.hiramatsu...@hitachi.com>
Signed-off-by: Masami Hiramatsu <mhira...@kernel.org>
---
[SNIP]
+ list_for_each_entry(note, &sdtlist, note_list) {
+ ret = snprintf(sdtgrp, 64, "sdt_%s", note->provider);
+ if (ret < 0)
+ break;
+ /* Try to find same-name entry */
+ entry = probe_cache__find_by_name(pcache, sdtgrp, note->name);
Wouldn't it be better to compare the build-id rather than the event
name? So, if there is a new sdt event added to a binary, its build-id will
change. And, if there is no change, the build-id remains the same.
Only if there is a change in the build-id, we can go for searching the
event name. This two level check can help optimizing the search.
+ if (!entry) {
+ entry = probe_cache_entry__new(NULL);
+ if (!entry) {
+ ret = -ENOMEM;
+ break;
+ }
+ entry->sdt = true;
+ ret = asprintf(&entry->spev, "%s:%s=%s", sdtgrp,
+ note->name, note->name);
+ if (ret < 0)
+ break;
+ entry->pev.event = strdup(note->name);
+ entry->pev.group = strdup(sdtgrp);
+ list_add_tail(&entry->list, &pcache->list);
+ }
+ ret = asprintf(&buf, "p:%s/%s %s:0x%llx",
+ sdtgrp, note->name, pathname,
+ sdt_note__get_addr(note));
+ if (ret < 0)
+ break;
+ strlist__add(entry->tevlist, buf);
+ free(buf);
+ entry = NULL;
+ }
+ if (entry)
+ probe_cache_entry__delete(entry);
+ cleanup_sdt_note_list(&sdtlist);
+ return ret;
+}
+
static int probe_cache_entry__write(struct probe_cache_entry *entry, int fd)
{
struct str_node *snode;
struct iovec iov[3];
+ const char *prefix = entry->sdt ? "%" : "#";
int ret;
- pr_debug("Writing cache: #%s\n", entry->spev);
- iov[0].iov_base = (void *)"#"; iov[0].iov_len = 1;
+ pr_debug("Writing cache: %s%s\n", prefix, entry->spev);
+ iov[0].iov_base = (void *)prefix; iov[0].iov_len = 1;
iov[1].iov_base = entry->spev; iov[1].iov_len = strlen(entry->spev);
iov[2].iov_base = (void *)"\n"; iov[2].iov_len = 1;
ret = writev(fd, iov, 3);
diff --git a/tools/perf/util/probe-file.h b/tools/perf/util/probe-file.h
index ba7b6d3..55322f1 100644
--- a/tools/perf/util/probe-file.h
+++ b/tools/perf/util/probe-file.h
@@ -21,6 +21,7 @@ int probe_file__del_strlist(int fd, struct strlist *namelist);
/* Cache of probe definitions */
struct probe_cache_entry {
struct list_head list;
+ bool sdt;
struct perf_probe_event pev;
char *spev;
struct strlist *tevlist;
@@ -35,6 +36,7 @@ struct probe_cache *probe_cache__new(const char *target);
int probe_cache__add_entry(struct probe_cache *pcache,
struct perf_probe_event *pev,
struct probe_trace_event *tevs, int ntevs);
+int probe_cache__scan_sdt(struct probe_cache *pcache, const char *pathname);
int probe_cache__commit(struct probe_cache *pcache);
void probe_cache__delete(struct probe_cache *pcache);
int probe_cache__remove_entries(struct probe_cache *pcache,
--
Thanks,
Hemant Kumar
