Messages in this thread | | | Date | Mon, 17 Dec 2001 15:15:15 -0800 (PST) | From | Davide Libenzi <> | Subject | Re: Scheduler ( was: Just a second ) ... |
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On Mon, 17 Dec 2001, Linus Torvalds wrote:
> > On Mon, 17 Dec 2001, Davide Libenzi wrote: > > > On Sat, 15 Dec 2001, Linus Torvalds wrote: > > > > > I just don't find it very interesting. The scheduler is about 100 lines > > > out of however-many-million (3.8 at least count), and doesn't even impact > > > most normal performace very much. > > > > Linus, sharing queue and lock between CPUs for a "thing" highly frequency > > ( schedule()s + wakeup()s ) accessed like the scheduler it's quite ugly > > and it's not that much funny. And it's not only performance wise, it's > > more design wise. > > "Design wise" is highly overrated. > > Simplicity is _much_ more important, if something commonly is only done a > few hundred times a second. Locking overhead is basically zero for that > case.
Few hundred is a nice definition because you can basically range from 0 to infinite. Anyway i agree that we can spend days debating about what this "few hundred" translate to, and i do not really want to.
> 4 cpu's are "high end" today. We can probably point to tens of thousands > of UP machines for each 4-way out there. The ratio gets even worse for 8, > and 16 CPU's is basically a rounding error. > > You have to prioritize. Scheduling overhead is way down the list.
You don't really have to serialize/prioritize, old Latins used to say "Divide Et Impera" ;)
- Davide
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