Messages in this thread | | | Date | Thu, 15 Apr 1999 14:38:27 +0200 (CEST) | From | Ingo Molnar <> | Subject | Re: CPU affinity |
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On Thu, 15 Apr 1999, Richard Gooch wrote:
> It looks to me that the underlying problem is that xosview steals the > CPU that the number cruncher is running on, instead of using the other > CPU (which I presume is idle). That shouldn't happen. If it does, it's > a bug.
this is not a bug, it's because xosview is an 'interactive' process, and such it has higher priority. (and the right to kick a lowprio process out, especially if xosview ran on that CPU previously). Btw., xosview's active timeslice is several msecs on a typical SMP box, so this is definitely not an outright bad decision by the scheduler.
i have the plan to do per-process and per-CPU 'cache-set tracking' via performance counters in 2.3 (basically what you see in 2.2 is already a variant of this). That one has a chance to weigh a process's priority with it's active cachesize.
anyway, even with 2.2.5 the expected behavior is that the number-cruching process settles on one CPU after some initial ping-pong, and xosview settles on some other CPU. If this does not happen _thats_ a bug. Anyway, be careful with xosview, it's obviously a bit tricky to measure scheduling with a tool that itself is rather intrusive as well ...
-- mingo
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