Messages in this thread |  | | | Date | Fri, 4 Feb 2000 00:21:11 +0100 (CET) | | From | Rik van Riel <> | | Subject | Re: Scheduler & semaphore patch for 2.2.14 ... |
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On Mon, 24 Jan 2000, Davide Libenzi wrote: > Monday, January 24, 2000 12:43 PM > Pavel Machek <pavel@suse.cz> wrote : > > Why not > > > > if ((c <= 0) && (nr_running >= smp_num_cpus)) /* To fix better */ > > > > and define smp_num_cpus to 1 if case of UP system? [I think it already > > _is_ defnied like this...] > > 100% agree.
That is a very bad plan. It would mean that the priority of processes isn't recalculated during a period of low cpu load.
That means that your running background process will have a high priority when your needing-cpu-once-in-a-while interactive task needs the CPU.
It also means that the priority of your interactive task is lower than what it should be and that the priority of the interactive task is higher than what it should be, leading to worse interactive performance.
At least, that's what I think it does. I'd love to see some test results from someone with enough time on their hands -- you probably need about 3 days to fully explore a scheduler and notice all of the strange things that might happen...
(I've created a nice scheduler patch and it has taken me some 3 days before I noticed one strange side effect of the patch, even though I'd really done my best to try and create as much different workloads as possible)
regards,
Rik -- The Internet is not a network of computers. It is a network of people. That is its real strength.
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