Em Fri, Sep 12, 2014 at 04:24:54PM +0900, Namhyung Kim escreveu: > Hi Arnaldo and Mike, > > On Thu, 11 Sep 2014 10:43:38 -0300, Arnaldo Carvalho de Melo wrote: > > Em Thu, Sep 11, 2014 at 02:43:12PM +0200, Mike Galbraith escreveu: > >> On Thu, 2014-09-11 at 17:09 +0900, Namhyung Kim wrote: > >> > On Tue, Sep 9, 2014 at 10:37 PM, Arnaldo Carvalho de Melo > >> > <a...@ghostprotocols.net> wrote: > >> > > Em Tue, Sep 09, 2014 at 01:54:01PM +0200, Mike Galbraith escreveu: > >> > >> Seems the now default on --children thingy doesn't like -U much. > >> > > > >> > > Namhyung, can you please take a look at this? > >> > > >> > So what is the problem here? > >> > >> Well, if you don't see anything wrong, I guess nothing at all. > > > > :-) > > > > I think that when we decide that it is so better to change defaults like > > we did this time, we should be required to add a big fat warning (a > > --tui popup, use the first lines on --stdio, etc) about why the default > > was changed and allow quick, easy opt out, restoring previous behaviour > > after the user, being warned, knows what to expect, tries it, and then > > is in a better position to decide if keeping the new default is what is > > desired. > > So the problem is that why it turned on --children option by default, > right? I thought you mentioned there's a problem with -U option and I > couldn't figure out what it is.
Yeah, at that point I thought the problem was that -U wasn't honoured in --children mode, but after I looked again at the output, it was all [k], so I thought that it was something else but didn't got back to the thread :-) > >> > >> Samples: 5K of event 'cycles', Event count (approx.): 2268660922 > >> > >> Children Self Symbol > >> > >> + 46.42% 0.04% [k] system_call_fastpath > > > >> I'll just turn it off until I figure out what cool stuff this is telling > >> me. why that symbol becomes the number one hit, and why total% > 100. > > > >> To me, it looks like top smoked it's breakfast, went to lala land ;-) > > > > Yeah, its confusing, I'll let Namhyung explain it ;-) > > Now I have three persion yell at me for this change. :) Hey, its not "yell" or something, I just think that it is under documented, and hey, perf is world renowned for being under developed, we don't need any further efforts in that area :-P > When this change was developping, Ingo said it'd be better if it looks > like output of sysprof as it's more popular for most (userland?) guys. > You can see the discussion in the following links: > > https://lkml.org/lkml/2013/10/31/97 > https://lkml.org/lkml/2013/11/1/85 > > The children field is a cumulative total overhead (for its all > children/callee) so sum of them would be more than 100%. And as Ingo > requested it sorts the output entries using children overhead so that > one can easily see higher level view of performance bottle-neck. yeah, yeah, but please have all this in the documentation :-) - Arnaldo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/