alex did you read the OOPSLA paper stefan or michael sent around about profiling and the default flaw in research approach?
Stef On Apr 29, 2011, at 12:40 AM, Alexandre Bergel wrote: > +1 > > Alexandre > > > On 28 Apr 2011, at 17:35, Michael Haupt wrote: > >> Hi Alex, >> >> On 29 April 2011 00:08, Alexandre Bergel <[email protected]> wrote: >>>> I think you're being a bit harsh on stack sampling there. It is exact >>>> enough to drive optimisation in some really high-performance VMs. It >>>> is also deterministic enough to yield data leading to very good >>>> performance results in those VMs. Whether focusing on counting >>>> messages instead of taking samples is more beneficial would have to be >>>> determined by experiment ... >>> >>> Yes, 25 pages of experiment :-) >> >> oh, I was not referring to your paper. I was referring to the general >> applicability of message counting as opposed to sampling. The latter >> is true-and-tried in many high performance VMs. For the former, an >> experiment has yielded good results (from what I take from this thread >> - I still haven't read your paper, sorry, it's on top of the pile) in >> a constrained setting. All I was saying is that it is not possible to >> conclude anything for the broader area from the experiments you >> conducted. But we're probably of the same opinion here. >> >>>> What you mean with "non-portable" I do not understand. >>> >>> The information about the execution time contained in your profile cannot >>> be compared with a new profile realized on a different machine, with a >>> different CPU. >> >> That is correct, but the approach itself is portable - may I quote >> you: "Most profilers, including MessageTally, count stack frames at a >> regular interval. This is doomed to be inexact, non-deterministic and >> non-portable". You weren't talking about the results. Those are >> obviously specific to the platform, clock frequency, L1/L2/L3 cache >> and memory sizes, application input (!) and other factors. >> >> Best, >> >> Michael >> > > -- > _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: > Alexandre Bergel http://www.bergel.eu > ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;. > > > > > >
