Re: [PATCH] tools/perf: Disable perf probe when libtraceevent is missing
> On 20-Jan-2023, at 7:58 PM, Arnaldo Carvalho de Melo wrote: > > Em Fri, Jan 20, 2023 at 05:32:56PM +0530, Athira Rajeev escreveu: >> While parsing the tracepoint events in parse_events_add_tracepoint() >> function, code checks for HAVE_LIBTRACEEVENT support. This is needed >> since libtraceevent is necessary for tracepoint. But while adding >> probe points, check for LIBTRACEEVENT is not done in case of perf probe. >> Hence, in environment with missing libtraceevent-devel, it is >> observed that adding a probe point works even though its not >> supported. > >> Example: >> Adding probe point: >> ./perf probe 'vfs_getname=getname_flags:72 pathname=result->name:string' >> Added new event: >>probe:vfs_getname(on getname_flags:72 with >> pathname=result->name:string) > >> You can now use it in all perf tools, such as: > >> perf record -e probe:vfs_getname -aR sleep 1 > >> But trying perf record: >> ./perf record -e probe:vfs_getname -aR sleep 1 >> event syntax error: 'probe:vfs_getname' >> \___ unsupported tracepoint >> libtraceevent is necessary for tracepoint support >> Run 'perf list' for a list of valid events >> >> Fix this by wrapping "builtin-probe" compilation and >> "perf probe" usage under "CONFIG_LIBTRACEEVENT" check. > > Humm, but 'perf probe' continues to work, as uou demoed above, the > problem is with the suggestion to use other perf tools that need to > parse tracefs and without libtraceevent, currently can't do it: > > [root@quaco ~]# perf probe 'vfs_getname=getname_flags:72 > pathname=result->name:string' > Added new event: > probe:vfs_getname(on getname_flags:72 with pathname=result->name:string) > > You can now use it in all perf tools, such as: > > perf record -e probe:vfs_getname -aR sleep 1 > > [root@quaco ~]# perf probe -l > probe:vfs_getname(on getname_flags:72@fs/namei.c with pathname) > [root@quaco ~]# perf trace -e probe:vfs_getname > perf: 'trace' is not a perf-command. See 'perf --help'. > [root@quaco ~]# cd /sys/kernel/tracing/events/probe/vfs_getname/ > [root@quaco vfs_getname]# ls > enable filter format hist id trigger > [root@quaco vfs_getname]# ls -la > total 0 > drwxr-x---. 2 root root 0 Jan 20 11:18 . > drwxr-x---. 3 root root 0 Jan 20 11:18 .. > -rw-r-. 1 root root 0 Jan 20 11:18 enable > -rw-r-. 1 root root 0 Jan 20 11:18 filter > -r--r-. 1 root root 0 Jan 20 11:18 format > -r--r-. 1 root root 0 Jan 20 11:18 hist > -r--r-. 1 root root 0 Jan 20 11:18 id > -rw-r-. 1 root root 0 Jan 20 11:18 trigger > [root@quaco vfs_getname]# > > But we can go on from there: > > [root@quaco tracing]# pwd > /sys/kernel/tracing > [root@quaco tracing]# echo 1 > > /sys/kernel/tracing/events/probe/vfs_getname/enable > [root@quaco tracing]# echo 1 > tracing_on > [root@quaco tracing]# head trace_pipe >systemd-oomd-979 [003] . 96369.978971: vfs_getname: > (getname_flags.part.0+0x6b/0x1c0) > pathname="/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service" >systemd-oomd-979 [003] . 96369.979022: vfs_getname: > (getname_flags.part.0+0x6b/0x1c0) > pathname="/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/memory.current" >systemd-oomd-979 [003] . 96369.979084: vfs_getname: > (getname_flags.part.0+0x6b/0x1c0) pathname="" >systemd-oomd-979 [003] . 96369.979162: vfs_getname: > (getname_flags.part.0+0x6b/0x1c0) > pathname="/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/memory.min" >systemd-oomd-979 [003] . 96369.979197: vfs_getname: > (getname_flags.part.0+0x6b/0x1c0) pathname="" >systemd-oomd-979 [003] . 96369.979267: vfs_getname: > (getname_flags.part.0+0x6b/0x1c0) > pathname="/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/memory.low" >systemd-oomd-979 [003] . 96369.979303: vfs_getname: > (getname_flags.part.0+0x6b/0x1c0) pathname="" >systemd-oomd-979 [003] . 96369.979372: vfs_getname: > (getname_flags.part.0+0x6b/0x1c0) > pathname="/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/memory.swap.current" >systemd-oomd-979 [003] . 96369.979406: vfs_getname: > (getname_flags.part.0+0x6b/0x1c0) pathname="" >systemd-oomd-979 [003] . 96369.979475: vfs_getname: > (getname_flags.part.0+0x6b/0x1c0) > pathname="/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/memory.stat" > [root@quaco tracing]# > > So you could instead replace the suggestion from: > > " > You can now use it in all perf tools, such as: > > perf record -e probe:vfs_getname -aR sleep 1 > " > > To: > > " > perf is not linked with libtraceevent, to use the new probe you > can use tracefs: > > cd /sys/kernel/tracing/ > echo 1 > events/probe/vfs_getname/enable > echo 1 > tracing_on > cat trace_pipe > " > >
Re: [PATCH] tools/perf: Disable perf probe when libtraceevent is missing
Em Fri, Jan 20, 2023 at 05:32:56PM +0530, Athira Rajeev escreveu: > While parsing the tracepoint events in parse_events_add_tracepoint() > function, code checks for HAVE_LIBTRACEEVENT support. This is needed > since libtraceevent is necessary for tracepoint. But while adding > probe points, check for LIBTRACEEVENT is not done in case of perf probe. > Hence, in environment with missing libtraceevent-devel, it is > observed that adding a probe point works even though its not > supported. > Example: > Adding probe point: > ./perf probe 'vfs_getname=getname_flags:72 pathname=result->name:string' > Added new event: > probe:vfs_getname(on getname_flags:72 with > pathname=result->name:string) > You can now use it in all perf tools, such as: > perf record -e probe:vfs_getname -aR sleep 1 > But trying perf record: > ./perf record -e probe:vfs_getname -aR sleep 1 > event syntax error: 'probe:vfs_getname' > \___ unsupported tracepoint > libtraceevent is necessary for tracepoint support > Run 'perf list' for a list of valid events > > Fix this by wrapping "builtin-probe" compilation and > "perf probe" usage under "CONFIG_LIBTRACEEVENT" check. Humm, but 'perf probe' continues to work, as uou demoed above, the problem is with the suggestion to use other perf tools that need to parse tracefs and without libtraceevent, currently can't do it: [root@quaco ~]# perf probe 'vfs_getname=getname_flags:72 pathname=result->name:string' Added new event: probe:vfs_getname(on getname_flags:72 with pathname=result->name:string) You can now use it in all perf tools, such as: perf record -e probe:vfs_getname -aR sleep 1 [root@quaco ~]# perf probe -l probe:vfs_getname(on getname_flags:72@fs/namei.c with pathname) [root@quaco ~]# perf trace -e probe:vfs_getname perf: 'trace' is not a perf-command. See 'perf --help'. [root@quaco ~]# cd /sys/kernel/tracing/events/probe/vfs_getname/ [root@quaco vfs_getname]# ls enable filter format hist id trigger [root@quaco vfs_getname]# ls -la total 0 drwxr-x---. 2 root root 0 Jan 20 11:18 . drwxr-x---. 3 root root 0 Jan 20 11:18 .. -rw-r-. 1 root root 0 Jan 20 11:18 enable -rw-r-. 1 root root 0 Jan 20 11:18 filter -r--r-. 1 root root 0 Jan 20 11:18 format -r--r-. 1 root root 0 Jan 20 11:18 hist -r--r-. 1 root root 0 Jan 20 11:18 id -rw-r-. 1 root root 0 Jan 20 11:18 trigger [root@quaco vfs_getname]# But we can go on from there: [root@quaco tracing]# pwd /sys/kernel/tracing [root@quaco tracing]# echo 1 > /sys/kernel/tracing/events/probe/vfs_getname/enable [root@quaco tracing]# echo 1 > tracing_on [root@quaco tracing]# head trace_pipe systemd-oomd-979 [003] . 96369.978971: vfs_getname: (getname_flags.part.0+0x6b/0x1c0) pathname="/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service" systemd-oomd-979 [003] . 96369.979022: vfs_getname: (getname_flags.part.0+0x6b/0x1c0) pathname="/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/memory.current" systemd-oomd-979 [003] . 96369.979084: vfs_getname: (getname_flags.part.0+0x6b/0x1c0) pathname="" systemd-oomd-979 [003] . 96369.979162: vfs_getname: (getname_flags.part.0+0x6b/0x1c0) pathname="/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/memory.min" systemd-oomd-979 [003] . 96369.979197: vfs_getname: (getname_flags.part.0+0x6b/0x1c0) pathname="" systemd-oomd-979 [003] . 96369.979267: vfs_getname: (getname_flags.part.0+0x6b/0x1c0) pathname="/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/memory.low" systemd-oomd-979 [003] . 96369.979303: vfs_getname: (getname_flags.part.0+0x6b/0x1c0) pathname="" systemd-oomd-979 [003] . 96369.979372: vfs_getname: (getname_flags.part.0+0x6b/0x1c0) pathname="/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/memory.swap.current" systemd-oomd-979 [003] . 96369.979406: vfs_getname: (getname_flags.part.0+0x6b/0x1c0) pathname="" systemd-oomd-979 [003] . 96369.979475: vfs_getname: (getname_flags.part.0+0x6b/0x1c0) pathname="/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/memory.stat" [root@quaco tracing]# So you could instead replace the suggestion from: " You can now use it in all perf tools, such as: perf record -e probe:vfs_getname -aR sleep 1 " To: " perf is not linked with libtraceevent, to use the new probe you can use tracefs: cd /sys/kernel/tracing/ echo 1 > events/probe/vfs_getname/enable echo 1 > tracing_on cat trace_pipe " wdyt? - Arnaldo > Signed-off-by: Athira Rajeev > --- > tools/perf/Build | 4 +++- > tools/perf/perf.c | 2 ++ > 2 files changed, 5 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/Build b/tools/perf/Build > index
[PATCH] tools/perf: Disable perf probe when libtraceevent is missing
While parsing the tracepoint events in parse_events_add_tracepoint()
function, code checks for HAVE_LIBTRACEEVENT support. This is needed
since libtraceevent is necessary for tracepoint. But while adding
probe points, check for LIBTRACEEVENT is not done in case of perf probe.
Hence, in environment with missing libtraceevent-devel, it is
observed that adding a probe point works even though its not
supported.
Example:
Adding probe point:
./perf probe 'vfs_getname=getname_flags:72 pathname=result->name:string'
Added new event:
probe:vfs_getname(on getname_flags:72 with
pathname=result->name:string)
You can now use it in all perf tools, such as:
perf record -e probe:vfs_getname -aR sleep 1
But trying perf record:
./perf record -e probe:vfs_getname -aR sleep 1
event syntax error: 'probe:vfs_getname'
\___ unsupported tracepoint
libtraceevent is necessary for tracepoint support
Run 'perf list' for a list of valid events
Fix this by wrapping "builtin-probe" compilation and
"perf probe" usage under "CONFIG_LIBTRACEEVENT" check.
Signed-off-by: Athira Rajeev
---
tools/perf/Build | 4 +++-
tools/perf/perf.c | 2 ++
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/tools/perf/Build b/tools/perf/Build
index 6dd67e502295..a138a2304929 100644
--- a/tools/perf/Build
+++ b/tools/perf/Build
@@ -33,7 +33,9 @@ ifeq ($(CONFIG_LIBTRACEEVENT),y)
perf-$(CONFIG_TRACE) += trace/beauty/
endif
-perf-$(CONFIG_LIBELF) += builtin-probe.o
+ifeq ($(CONFIG_LIBTRACEEVENT),y)
+ perf-$(CONFIG_LIBELF) += builtin-probe.o
+endif
perf-y += bench/
perf-y += tests/
diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 82bbe0ca858b..7b0d79284d5a 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -80,9 +80,11 @@ static struct cmd_struct commands[] = {
#ifdef HAVE_LIBTRACEEVENT
{ "sched", cmd_sched, 0 },
#endif
+#ifdef HAVE_LIBTRACEEVENT
#ifdef HAVE_LIBELF_SUPPORT
{ "probe", cmd_probe, 0 },
#endif
+#endif
#ifdef HAVE_LIBTRACEEVENT
{ "kmem", cmd_kmem, 0 },
{ "lock", cmd_lock, 0 },
--
2.39.0
