On Friday 29 August 2014 04:33:43 Simon Wise did opine And Gene did reply: > On 29/08/14 15:40, Len Ovens wrote: > > I don't know that the physical technology matters so much as the OS > > being hyperthreading aware and treating each pair of cores like one. > > That is making sure that core 0 does not do anything that takes too > > long for core 1 to meet it's dead line. I do not know if new Linux > > kernels do this, older ones did not. They logged that the chip had > > hyperthreading, but still seemed to treat two threads as two > > different cores. > > > > Certainly, common wisdom has not kept up with tech changes. I would > > be nice to know more. > > Not quite on topic, since this isn't to do with Hyper-threading, but > certainly the Linux scheduler has been getting much more sophisticated > in dealing with different kinds of cores ... in ARM it now schedules > tasks for chips with some smaller cores and some faster ones, keeping > them busy with suitable sized tasks. > > The ARM kernels running the most recent Samsung tablets (with 4 big > plus 4 little cores) have this GTS in the 3.14 kernels ... it runs all > 8 cores together assigning tasks appropriate to each, rather than just > switching between big or little of each pair to save power. Selling > hardware on that scale certainly brings a budget, and since the kernel > is GPL it can't be kept in-house. > > Seems that 3.14 has also added a deadline-based scheduler that is > closer to what audio needs from realtime than the extremely low > latency preemption based on priorities that the two older realtime > schedulers offer. > > http://www.linuxfoundation.org/news-media/blogs/browse/2014/01/deadline > -scheduling-314 > > Simon This message is timely as I haven't tried the deadline scheduler in several years, so I just switched the config to make it the default, and its building now. Perhaps it will actually improve both the USB lags, and the network video playback I get here. Thank you for an informative post. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
