Messages in this thread | | | Date | Tue, 20 Mar 2012 16:28:09 -0700 | From | Arun Sharma <> | Subject | Re: [PATCH] perf: Add a new sort order: SORT_INCLUSIVE (v4) |
| |
On 3/19/12 8:57 AM, Frederic Weisbecker wrote:
>>> Each hist have a period of 1, but the total period is 1. >>> So the end result should be (IIUC): >>> >>> 100% foo a >>> 100% foo b >>> | >>> --- a >>> 100% foo c >>> | >>> --- b >>> | >>> --- c >>> >> >> That is correct. The first column no longer adds up to 100%. > > So do we really want this? >
I think so. It's a different way of presenting the data. Pie chart vs a bar chart of OS market share where people may be using more than one OS.
I'll post some documentation updates.
>> If we don't do this, total_period will be inflated. > > Yeah right I've just tried and callchains look right. I'm just puzzled > by the percentages: >
Thanks for testing this!
> + 98,99% [k] execve > + 98,99% [k] stub_execve > + 98,99% [k] do_execve > + 98,99% [k] do_execve_common > + 98,99% [k] sys_execve > + 53,12% [k] __libc_start_main > + 53,12% [k] cmd_record
These look like they belong to the perf binary and are incorrectly classified as kernel samples. Problem is that callchain_get() is not populating the privilege level - it's simply propagating the privilege level of the sample:
+ for (i = 0; i < cursor->nr; i++) { + struct addr_location al_child = *al; + + err = callchain_get(&iter, &al_child);
Not all fields of al_child are populated by callchain_get().
> + 53,12% [k] T.101 > + 53,12% [k] main > + 53,12% [k] run_builtin > + 52,11% [k] perf_evlist__prepare_workload > + 52,09% [k] T.1163
The rest of them look ok to me. If something doesn't make sense, please point me at the output of "perf script".
> >> >>> Also this feature reminds me a lot the -b option in perf report. >>> Branch sorting and callchain inclusive sorting are a bit different in >>> the way they handle the things but the core idea is the same. Callchains >>> are branches as well. >>> >> >> Yes - I kept asking why the branch stack stuff doesn't use the >> existing callchain logic. > > Because I fear that loops branches could make the tree representation useless. >
The loops could happen in callgraphs too right (eg: recursive programs)? The other problem in branch stacks/LBR is that they're sampled branches. Just because I got a sample with:
a -> b b -> c
doesn't necessarily mean that the callchain was a -> b -> c.
I still don't have the branch stack setup working properly. But I'm now more sympathetic to the view that last branch sampling and callchains may have different representations in perf.
-Arun
| |