Messages in this thread | | | From | "Gonzalez, Inaky" <> | Subject | RE: [2.4.17/18pre] VM and swap - it's really unusable | Date | Tue, 8 Jan 2002 13:45:35 -0800 |
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> And while I'm enumerating differences, the preemptable kernel > (in this > incarnation) has a slight per-spinlock cost, while the > non-preemptable kernel > has the fixed cost of checking for rescheduling, at intervals > throughout all > 'interesting' kernel code, essentially all long-running > loops.
For a general case, that cost is leveraged by the improvement in scheduling, by filling out the IO channels better, and thus, using most resources more efficiently. I did some dirty tests that showed that the preemptible kernel performed more or less one second better than the normal one when unzipping and compiling a kernel [dirty general case]. The std deviation is around the time difference, so we can quite conclude the impact is zero -- asides from the improvement in responsiveness].
Please see my message to the mailing list at http://www.geocrawler.com/archives/3/14905/2001/11/0/7074067/ [the excel spreadsheet is available at request].
Iñaky Pérez González -- (503) 677 6807 I do not speak for Intel Corp, opinions are my own. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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