Re: [tip:perf/core] perf trace: Allow overriding global --max-stack per event

[Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>]

Hi Arnaldo,

This commit seems to be causing a regression:

  $ ./perf trace record -g ls


Perf compiled from acme/perf/core:

  $ ./perf trace -i perf.data
     0.200 ( 0.016 ms): ls/19722 brk(                                                 
     0.367 ( 0.024 ms): ls/19722 access(filename: 0xa1438b70, mode: R                 
     0.401 ( 0.019 ms): ls/19722 open(filename: 0xa1438978, flags: CLOEXEC            

           Missing calltraces ^^^^^^^^^


Distro perf:

  $ perf trace -i perf.data
     0.200 ( 0.016 ms): ls/19722 brk(                                                 
                                       do_syscall_trace_leave ([kernel.kallsyms])
                                       [0] ([unknown])
                                       syscall_exit_work ([kernel.kallsyms])
                                       brk (/usr/lib64/ld-2.17.so)
                                       _dl_sysdep_start (/usr/lib64/ld-2.17.so)
                                       _dl_start_final (/usr/lib64/ld-2.17.so)
                                       _dl_start (/usr/lib64/ld-2.17.so)
                                       _start (/usr/lib64/ld-2.17.so)
     0.367 ( 0.024 ms): ls/19722 access(filename: 0xa1438b70, mode: R                 
                                       do_syscall_trace_leave ([kernel.kallsyms])
                                       [0] ([unknown])
                                       syscall_exit_work ([kernel.kallsyms])
                                       access (/usr/lib64/ld-2.17.so)
                                       dl_main (/usr/lib64/ld-2.17.so)
                                       _dl_sysdep_start (/usr/lib64/ld-2.17.so)
                                       _dl_start_final (/usr/lib64/ld-2.17.so)
                                       _dl_start (/usr/lib64/ld-2.17.so)
                                       _start (/usr/lib64/ld-2.17.so)
     0.401 ( 0.019 ms): ls/19722 open(filename: 0xa1438978, flags: CLOEXEC            
                                       do_syscall_trace_leave ([kernel.kallsyms])
                                       [0] ([unknown])
                                       syscall_exit_work ([kernel.kallsyms])
                                       open64 (/usr/lib64/ld-2.17.so)


Patch something like below should fix the issue ??

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 531d43b..d0ace22 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1642,9 +1642,12 @@ static int trace__resolve_callchain(struct trace *trace, struct perf_evsel *evse
 				    struct callchain_cursor *cursor)
 {
 	struct addr_location al;
+	int max_stack = evsel->attr.sample_max_stack ?
+			evsel->attr.sample_max_stack:
+			trace->max_stack;
 
 	if (machine__resolve(trace->host, &al, sample) < 0 ||
-	    thread__resolve_callchain(al.thread, cursor, evsel, sample, NULL, NULL, evsel->attr.sample_max_stack))
+	    thread__resolve_callchain(al.thread, cursor, evsel, sample, NULL, NULL, max_stack))
 		return -1;
 
 	return 0;


Thanks,
Ravi


On 01/17/2018 10:04 PM, tip-bot for Arnaldo Carvalho de Melo wrote:
> Commit-ID:  bd3dda9ab0fbdb8a91a2e869d93a0c9692b8444f
> Gitweb:     https://git.kernel.org/tip/bd3dda9ab0fbdb8a91a2e869d93a0c9692b8444f
> Author:     Arnaldo Carvalho de Melo <acme@redhat.com>
> AuthorDate: Mon, 15 Jan 2018 11:33:53 -0300
> Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
> CommitDate: Wed, 17 Jan 2018 10:23:33 -0300
>
> perf trace: Allow overriding global --max-stack per event
>
> The per-event max-stack setting wasn't overriding the global --max-stack
> setting:
>
>   # perf trace --no-syscalls --max-stack 4 -e probe_libc:inet_pton/call-graph=dwarf,max-stack=2/ ping -6 -c 1 ::1
>   PING ::1(::1) 56 data bytes
>   64 bytes from ::1: icmp_seq=1 ttl=64 time=0.072 ms
>
>   --- ::1 ping statistics ---
>   1 packets transmitted, 1 received, 0% packet loss, time 0ms
>   rtt min/avg/max/mdev = 0.072/0.072/0.072/0.000 ms
>        0.000 probe_libc:inet_pton:(7feb7a998350))
>                                          __inet_pton (inlined)
>                                          gaih_inet.constprop.7 (/usr/lib64/libc-2.26.so)
>                                          __GI_getaddrinfo (inlined)
>                                          [0xffffaa39b6108f3f] (/usr/bin/ping)
>   #
>
> Fix it:
>
>   # perf trace --no-syscalls --max-stack 4 -e probe_libc:inet_pton/call-graph=dwarf,max-stack=2/ ping -6 -c 1 ::1
>   PING ::1(::1) 56 data bytes
>   64 bytes from ::1: icmp_seq=1 ttl=64 time=0.073 ms
>
>   --- ::1 ping statistics ---
>   1 packets transmitted, 1 received, 0% packet loss, time 0ms
>   rtt min/avg/max/mdev = 0.073/0.073/0.073/0.000 ms
>        0.000 probe_libc:inet_pton:(7f1083221350))
>                                          __inet_pton (inlined)
>                                          gaih_inet.constprop.7 (/usr/lib64/libc-2.26.so)
>   #
>
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Cc: David Ahern <dsahern@gmail.com>
> Cc: Hendrick Brueckner <brueckner@linux.vnet.ibm.com>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
> Cc: Wang Nan <wangnan0@huawei.com>
> Link: https://lkml.kernel.org/n/tip-ic3g837xg8ob3kcpkspxwz0g@git.kernel.org
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
>  tools/perf/builtin-trace.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> index ee85c29..531d43b 100644
> --- a/tools/perf/builtin-trace.c
> +++ b/tools/perf/builtin-trace.c
> @@ -1644,7 +1644,7 @@ static int trace__resolve_callchain(struct trace *trace, struct perf_evsel *evse
>  	struct addr_location al;
>
>  	if (machine__resolve(trace->host, &al, sample) < 0 ||
> -	    thread__resolve_callchain(al.thread, cursor, evsel, sample, NULL, NULL, trace->max_stack))
> +	    thread__resolve_callchain(al.thread, cursor, evsel, sample, NULL, NULL, evsel->attr.sample_max_stack))
>  		return -1;
>
>  	return 0;
> @@ -2423,6 +2423,18 @@ static int trace__run(struct trace *trace, int argc, const char **argv)
>  	trace->multiple_threads = thread_map__pid(evlist->threads, 0) == -1 ||
>  				  evlist->threads->nr > 1 ||
>  				  perf_evlist__first(evlist)->attr.inherit;
> +
> +	/*
> +	 * Now that we already used evsel->attr to ask the kernel to setup the
> +	 * events, lets reuse evsel->attr.sample_max_stack as the limit in
> +	 * trace__resolve_callchain(), allowing per-event max-stack settings
> +	 * to override an explicitely set --max-stack global setting.
> +	 */
> +	evlist__for_each_entry(evlist, evsel) {
> +		if ((evsel->attr.sample_type & PERF_SAMPLE_CALLCHAIN) &&
> +		    evsel->attr.sample_max_stack == 0)
> +			evsel->attr.sample_max_stack = trace->max_stack;
> +	}
>  again:
>  	before = trace->nr_events;
>
>