Hi Markus, On Sun, Sep 4, 2016 at 3:45 PM, SF Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx> wrote: >>> I hope so. - I propose to give the refactorings "Reduce scope of variable" >>> and "Extract a function" (and the corresponding consequences) another look. >> >> So you _think_ it does. Come back with real proof. > > Which test environments would you find acceptable for further clarification? Compiling it on GCC for Sparc, obviously. >> I must also point out that these sorts of optimisations are things the >> compiler does automatically when compiling this code. > > Do you take this detail for granted? I trust that the GCC developers have done their work well. >> Therefore it's highly likely that this change will make absolutely >> no difference whatsoever. > > I find this outcome unlikely. Then provide proof. >> (And no it won't improve compile speed in any justifiable way) > > This was not a goal of my update suggestion for the function "bpf_jit_compile". I'm looking for some glimmer of usefullness in this patch. I'm not seeing any. >>> It is generally possible that a specific code generation variant will also affect >>> the run time properties you mentioned. >> >> It's _possible_? Come back with benchmarks. > > Which code generation variant would be useful to be clarified further? > > Should we avoid to compare software things similar to "apples" and "oranges" > (while these fruits can make more fun)? ;-) Write a benchmark that exercises this function. Measure the time it took without this change, measure the time it took with this change, is there a difference. You cannot expect people to take you seriously if you're proposing performance changes without any actual ability or interest in producing performance related data to go along with them. >> I must also point out that this is a "slow path" i.e. as long as it's >> not stupidly inefficient, the speed doesn't matter that much. > > Can this execution path become warmer (or even "hot") for some other use cases? That is for you to prove. >> This change isn't going to improve the speed of this function by any amount >> that matters. > > This is also possible. > > >> Unless you have some pretty damn good proof that these changes improve things, >> there is absolutely no reason to take them as-is > > Would you care for a better source code structure? You're essentially saying "I think doing things this way is better" and providing _nothing_ else. I think that things are perfectly fine the way they are. Convince me with data or something else. Was this suggested by some expert? Is this part of some big tree-wide effort to do this that was started by some expert? Did someone do this to some other driver and you're applying the same fix elsewhere? >> - you are making the code longer > > Yes. - This is true for the suggested update in this function. > > >> and more difficult to read for no benefit > > I proposed specific benefits for this software module. What benefits? You have not proved that this change produces any useful benefits. >> and wasting everyone's time in the process. > > I assume that a few contributors can take the presented ideas for further considerations. > Will their value evolve a bit more later? I am subscribed to four fairly high traffic mailing lists and I read hundreds of patches each week. You are the only person proposing changes like these ones as you are (as far as I know) the only person who thinks they have any value. Thanks, -- Julian Calaby Email: julian.calaby@xxxxxxxxx Profile: http://www.google.com/profiles/julian.calaby/ -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
