By: Patrick Chase (patrickjchase.delete@this.gmail.com), January 9, 2015 11:54 am
Room: Moderated Discussions
coppice (coppice.delete@this.dis.org) on January 8, 2015 10:18 pm wrote:
> juanrga (nospam.delete@this.juanrga.com) on January 7, 2015 6:03 am wrote:
> > Recently Intel's Crago and coworkers have published a set of latency techniques "to
> > reach the energy efficiency goals of future 1000-core data-parallel processors"
> > [1]. They evaluated and rejected a number of existent latency techniques, including
> > Linus beloved OoO.
> >
> > [1] http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6522327&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6522327
> >
> Interesting paper. Perhaps you should read it some time. On the other hand, if you have
> read it you should be ashamed of so blatantly misrepresenting its conclusions about OoO.
For those who don't have IEEE subs and are too lazy to search, here's a direct link (found via Neal Crago's personal site):
https://6ddba3e7c48ea938c879adbfec05061acc32bb7e.googledrive.com/host/0Bz5Zlai57wAhVUFMbjJGeG1mcnc/papers/crago_hpca13.pdf
Figure 7 on p. 303 shows relative energy efficiency across a range of workloads. The OoO flavor they evaluated does quite well, often coming second best (and typically within a couple/few tens of percent) to their preferred "hybrid" approach of SMT + decoupled.
These aren't the sort of improvements that will drive a platform shift - If anything this should be interpreted as a very negative result from the standpoint of folks like juanrga, as it fails to show a compelling energy-efficiency benefit from the evaluated alternatives to OoO.
Perhaps it's time to resurrect the talk of banning juanrga?
> juanrga (nospam.delete@this.juanrga.com) on January 7, 2015 6:03 am wrote:
> > Recently Intel's Crago and coworkers have published a set of latency techniques "to
> > reach the energy efficiency goals of future 1000-core data-parallel processors"
> > [1]. They evaluated and rejected a number of existent latency techniques, including
> > Linus beloved OoO.
> >
> > [1] http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6522327&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6522327
> >
> Interesting paper. Perhaps you should read it some time. On the other hand, if you have
> read it you should be ashamed of so blatantly misrepresenting its conclusions about OoO.
For those who don't have IEEE subs and are too lazy to search, here's a direct link (found via Neal Crago's personal site):
https://6ddba3e7c48ea938c879adbfec05061acc32bb7e.googledrive.com/host/0Bz5Zlai57wAhVUFMbjJGeG1mcnc/papers/crago_hpca13.pdf
Figure 7 on p. 303 shows relative energy efficiency across a range of workloads. The OoO flavor they evaluated does quite well, often coming second best (and typically within a couple/few tens of percent) to their preferred "hybrid" approach of SMT + decoupled.
These aren't the sort of improvements that will drive a platform shift - If anything this should be interpreted as a very negative result from the standpoint of folks like juanrga, as it fails to show a compelling energy-efficiency benefit from the evaluated alternatives to OoO.
Perhaps it's time to resurrect the talk of banning juanrga?
