linux-kernel - Re: [PATCH 01/17] perf hists: Basic support of hierarchical report view

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Date:	Fri, 22 Jan 2016 12:37:49 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Jiri Olsa <jolsa@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	Andi Kleen <andi@...stfloor.org>,
	Wang Nan <wangnan0@...wei.com>
Subject: Re: [PATCH 01/17] perf hists: Basic support of hierarchical report
 view

On Fri, Jan 22, 2016 at 07:43:12PM +0900, Namhyung Kim wrote:
> Hi Jiri,
> 
> On Thu, Jan 21, 2016 at 02:35:58PM +0100, Jiri Olsa wrote:
> > On Thu, Jan 21, 2016 at 09:55:52PM +0900, Namhyung Kim wrote:
> > > > would it make more sense to do this in 'in-tree addition' path?
> > > > and keep the resort functions to do only resort stuff
> > > 
> > > I don't follow.  There're 3 path to handle hist entries - let's say
> > > them as 'addition', 'collapsing', and 'resort'.  This function does
> > > the 'collapsing' part - it was originally intended to merge sharable
> > > entries (namely for same 'comm' among different threads).  But I used
> > > it to build a hierarchy since I found it useful as follows:
> > > 
> > >   1. it requires smaller change than doing it in the 'addition' path
> > >   2. it can reuse current callback-based 'addition' paths so mem- and
> > >      branch-mode can be supported easily (but it needs test..).
> > >   3. the 'addition' path can be parallelized so it'll increase memory
> > >      footprint if it build temporary local hierarchies during the path.
> > > 
> > > The 'resort' path always do sorting only..
> > 
> > well, you are adding/duplicating entries now in resort path
> > and that is not just 'sorting only'
> 
> As I said, this is not the 'resort' path, the 'resort' path is the
> subject of patch 02/17.

ok, I took the collapsing as a part of resort

> 
> 
> > 
> > you allow only sort and tracepoint entries to be added in
> > hierrarych view, so there's no resort needed, but still it
> > could be added in future? not sure
> 
> Resorting is still needed since it should sort entries by overhead
> (period).  Anyway, in this 'collapsing' path, we need to build a
> hierarchy to be sorted at the resort path.
> 
> 
> > 
> > it still makes more sense to me to do this in 'addition' path,
> > because you basically add new entries
> > 
> > but have no other grounds for this also I might be missing something ;-)
> 
> What about thinking like this?
> 
> 1. addition   - add samples into hist entries
> 2. collapsing - build complete hists (hierarchy) to be sorted
> 3. resort     - sort final entries based on the sort keys

ok, sounds good.. maybe we could use some other name
for collapsing then.. like build,setup or such

thanks for bearing with me ;-)
jirka