| Message ID | 20240415154921.4998-3-jianfeng.w.wang@oracle.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | trace-cmd ftrace: support function retval feature in function_graph | expand |
On 4/15/24 8:49 AM, Jianfeng Wang wrote: > Added internal options for ftrace, and included a fgraph:retval > option that will print the function names at the function exit. > When the option is set and the function_graph retval feature is > supported by the kernel, each function's return value will be > printed as '(ret=retval)'. > > Signed-off-by: Jianfeng Wang <jianfeng.w.wang@oracle.com> > --- > lib/trace-cmd/trace-ftrace.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/lib/trace-cmd/trace-ftrace.c b/lib/trace-cmd/trace-ftrace.c > index cb05d88c..fecc3d69 100644 > --- a/lib/trace-cmd/trace-ftrace.c > +++ b/lib/trace-cmd/trace-ftrace.c > @@ -23,6 +23,12 @@ struct tep_plugin_option trace_ftrace_options[] = { > .description = > "Show the depth of each entry", > }, > + { > + .name = "retval", > + .plugin_alias = "fgraph", > + .description = > + "Print function retval at function exit in function graph", > + }, > { > .name = NULL, > } > @@ -30,6 +36,7 @@ struct tep_plugin_option trace_ftrace_options[] = { > > static struct tep_plugin_option *fgraph_tail = &trace_ftrace_options[0]; > static struct tep_plugin_option *fgraph_depth = &trace_ftrace_options[1]; > +static struct tep_plugin_option *fgraph_retval = &trace_ftrace_options[2]; > > static int find_ret_event(struct tracecmd_ftrace *finfo, struct tep_handle *pevent) > { > @@ -232,7 +239,7 @@ print_graph_entry_leaf(struct trace_seq *s, > ret = trace_seq_printf(s, " (%lld)", depth); > > /* Return Value */ > - if (ret && fgraph_retval_supported) > + if (ret && fgraph_retval->set && fgraph_retval_supported) > ret = trace_seq_printf(s, " (ret=%lld)", retval); > > return ret; > @@ -378,7 +385,7 @@ fgraph_ret_handler(struct trace_seq *s, struct tep_record *record, > trace_seq_printf(s, " (%lld)", depth); > > /* Return Value */ > - if (fgraph_retval_supported) > + if (fgraph_retval->set && fgraph_retval_supported) > trace_seq_printf(s, " (ret=%lld)", retval); > > return 0; Kindly ask for reviews on this patchset :) Here, I include a more detailed effect of this patchset. * Record process The trace-cmd record process is not changed. # trace-cmd record -p function_graph -P 4331 trace-cmd can communicate with the kernel to get the actual funcgraph_exit event format. If the kernel supports ftrace-retval, then trace-cmd will use the updated event format that has "retval" field. * Report process By default, trace-cmd won't print each function's retval. # trace-cmd report However, if one wants to turn it on and the kernel supports the feature, do the following (through fgraph plugin options): # trace-cmd report -O fgraph:depth -O fgraph:tailprint -O fgraph:retval The output looks like this: <idle>-0 [012] d.... 361.071503: funcgraph_entry: | switch_mm_irqs_off() { (0) <idle>-0 [012] d.... 361.071507: funcgraph_entry: 0.491 us | load_new_mm_cr3(); (1) (ret=0) <idle>-0 [012] d.... 361.071508: funcgraph_entry: 0.251 us | switch_ldt(); (1) (ret=0) <idle>-0 [012] d.... 361.071508: funcgraph_exit: 5.901 us | } /* switch_mm_irqs_off */ (0) (ret=0) Each function's return value will be printed at the function's return point.
On Tue, 30 Apr 2024 15:45:43 -0700
Jianfeng Wang <jianfeng.w.wang@oracle.com> wrote:
> Kindly ask for reviews on this patchset :)
I haven't forgotten these patches ;-)
I was hoping to get to the userspace side this month, but things came up on
the kernel side I had to take care of.
I'm hoping to get to them in then next week or so.
Thanks,
-- Steve
Finally got the time to look at these patches ;-) On Mon, 15 Apr 2024 08:49:21 -0700 Jianfeng Wang <jianfeng.w.wang@oracle.com> wrote: > +++ b/lib/trace-cmd/trace-ftrace.c > @@ -23,6 +23,12 @@ struct tep_plugin_option trace_ftrace_options[] = { > .description = > "Show the depth of each entry", > }, > + { > + .name = "retval", > + .plugin_alias = "fgraph", > + .description = > + "Print function retval at function exit in function graph", > + }, Honestly, I don't think this should be an option. Or if it is, it should be default on. If the retval exists in the trace, it should just be printed. Why ask the user to show it when they spent the time to enable it in the recording? Thanks! -- Steve > { > .name = NULL, > }
On 5/16/24 5:53 PM, Steven Rostedt wrote: > > Finally got the time to look at these patches ;-) > > On Mon, 15 Apr 2024 08:49:21 -0700 > Jianfeng Wang <jianfeng.w.wang@oracle.com> wrote: > >> +++ b/lib/trace-cmd/trace-ftrace.c >> @@ -23,6 +23,12 @@ struct tep_plugin_option trace_ftrace_options[] = { >> .description = >> "Show the depth of each entry", >> }, >> + { >> + .name = "retval", >> + .plugin_alias = "fgraph", >> + .description = >> + "Print function retval at function exit in function graph", >> + }, > > Honestly, I don't think this should be an option. Or if it is, it > should be default on. If the retval exists in the trace, it should just > be printed. Why ask the user to show it when they spent the time to > enable it in the recording? > > Thanks! > > -- Steve > Thanks for your response! I make it a default-off option because the feature changes the output format of the 'trace-cmd report'. So to be on the safe side, keep the original format by default. Also, the kernel has options (i.e., options/funcgraph-retval and options/funcgraph-retval-hex) to enable printing functions' retval in trace.log From my point of view, I'd like to see the retval on by default. If you are okay, I'd like to make it default on and add an option to display retval in hex. >> { >> .name = NULL, >> }
On Fri, 17 May 2024 11:50:29 -0700 Jianfeng Wang <jianfeng.w.wang@oracle.com> wrote: > > Honestly, I don't think this should be an option. Or if it is, it > > should be default on. If the retval exists in the trace, it should just > > be printed. Why ask the user to show it when they spent the time to > > enable it in the recording? > > > > I make it a default-off option because the feature changes the output format of > the 'trace-cmd report'. So to be on the safe side, keep the original format by > default. Also, the kernel has options (i.e., options/funcgraph-retval and > options/funcgraph-retval-hex) to enable printing functions' retval in trace.log > > >From my point of view, I'd like to see the retval on by default. If you are > okay, I'd like to make it default on and add an option to display retval in hex. Yeah, we can keep both as an option, but make the retval default on. It will not change default behavior, as it should only be shown if retval was recorded in the first place. If it wasn't recorded, the behavior should be the same regardless of if the retval option is enabled or not in the trace-cmd output. -- Steve
On 5/17/24 12:00 PM, Steven Rostedt wrote: > On Fri, 17 May 2024 11:50:29 -0700 > Jianfeng Wang <jianfeng.w.wang@oracle.com> wrote: > >>> Honestly, I don't think this should be an option. Or if it is, it >>> should be default on. If the retval exists in the trace, it should just >>> be printed. Why ask the user to show it when they spent the time to >>> enable it in the recording? >>> > >> >> I make it a default-off option because the feature changes the output format of >> the 'trace-cmd report'. So to be on the safe side, keep the original format by >> default. Also, the kernel has options (i.e., options/funcgraph-retval and >> options/funcgraph-retval-hex) to enable printing functions' retval in trace.log >> >> >From my point of view, I'd like to see the retval on by default. If you are >> okay, I'd like to make it default on and add an option to display retval in hex. > > Yeah, we can keep both as an option, but make the retval default on. > > It will not change default behavior, as it should only be shown if retval > was recorded in the first place. If it wasn't recorded, the behavior should > be the same regardless of if the retval option is enabled or not in the > trace-cmd output. > > -- Steve SGTM. I will send a v2. Thanks, Jianfeng
diff --git a/lib/trace-cmd/trace-ftrace.c b/lib/trace-cmd/trace-ftrace.c index cb05d88c..fecc3d69 100644 --- a/lib/trace-cmd/trace-ftrace.c +++ b/lib/trace-cmd/trace-ftrace.c @@ -23,6 +23,12 @@ struct tep_plugin_option trace_ftrace_options[] = { .description = "Show the depth of each entry", }, + { + .name = "retval", + .plugin_alias = "fgraph", + .description = + "Print function retval at function exit in function graph", + }, { .name = NULL, } @@ -30,6 +36,7 @@ struct tep_plugin_option trace_ftrace_options[] = { static struct tep_plugin_option *fgraph_tail = &trace_ftrace_options[0]; static struct tep_plugin_option *fgraph_depth = &trace_ftrace_options[1]; +static struct tep_plugin_option *fgraph_retval = &trace_ftrace_options[2]; static int find_ret_event(struct tracecmd_ftrace *finfo, struct tep_handle *pevent) { @@ -232,7 +239,7 @@ print_graph_entry_leaf(struct trace_seq *s, ret = trace_seq_printf(s, " (%lld)", depth); /* Return Value */ - if (ret && fgraph_retval_supported) + if (ret && fgraph_retval->set && fgraph_retval_supported) ret = trace_seq_printf(s, " (ret=%lld)", retval); return ret; @@ -378,7 +385,7 @@ fgraph_ret_handler(struct trace_seq *s, struct tep_record *record, trace_seq_printf(s, " (%lld)", depth); /* Return Value */ - if (fgraph_retval_supported) + if (fgraph_retval->set && fgraph_retval_supported) trace_seq_printf(s, " (ret=%lld)", retval); return 0;
Added internal options for ftrace, and included a fgraph:retval option that will print the function names at the function exit. When the option is set and the function_graph retval feature is supported by the kernel, each function's return value will be printed as '(ret=retval)'. Signed-off-by: Jianfeng Wang <jianfeng.w.wang@oracle.com> --- lib/trace-cmd/trace-ftrace.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)