On Wed, 2005-07-13 at 10:49 -0400, Eric Dantan Rzewnicki wrote: > On Tue, Jul 12, 2005 at 07:34:07PM -0400, Lee Revell wrote: > > On Wed, 2005-07-13 at 01:03 +0200, Florian Schmidt wrote: > > > Some semieducated blabbering ahead (might be all wrong): > > > I think i once read that interrupt handling "short circuits" the linux > > > scheduler (in the sense that not only at every timer interrupt but also > > > at the end of finishing any interrupt handler the kernel looks which > > > processes are ready to run etc. and maybe there's a high prio process > > > waiting just for that interrupt (by i.e. polling or reading on a device > > > file). > > > So for all those realtime processes that depend on events that are > > > triggering interrupts (like soundcards' irqs) the timer interrupt really > > > doesn't matter. I'm not sure at all though this applies to midi handling > > > (and especially to alsa_seq when routing from one app to another) or is > > > even correct in any sense at all :) > > > Anyone can shed light? > > Correct, it's not an issue for apps driven by hardware interrupts like > > JACK, because the sound card consumes data at a constant rate. But for > > MIDI or video where you have to periodically push data to the device it > > matters. > > What is driving the kernel-devs to regress on this issue? > Saving battery on laptops. The only performance numbers anyone posted indicated HZ=250 sped up a kernel compile on a 16 CPU machine (!) by ~5%, and this was after the fact. Not exactly compelling... But since Linus and Andrew apparently all use laptops, us desktop people are screwed... Lee
