On Tue, Feb 16, 2010 at 07:50:02AM +0100, Max Müller wrote: | Clark Williams schrieb: | >On Mon, 15 Feb 2010 10:32:54 +0100 | >Max Müller <mxmr@xxxxxxx> wrote: | >>>I'd say you're doing pretty good keeping under 50us. You might want to | >>>try it under a heavier load than the shell script you've been running. | >>>If you don't want to fool with rteval, try kicking off a kernel compile | >>>in another window like this: | >>> | >>>$ while true; do make -j4 clean bzImage modules; done | >>> | >>>and then run cyclictest. A kernel compile with parallel jobs (-j) is a | >>>good overall load of computation and I/O. | >>> | >>I tested now like you told me with irqbalance and cpuspeed | >>services disabled. I hope i made the right for disabling | >>irqbalance, i used the kernel parameter acpi_no_irqbalance. Is | >>this correct? Unfortunately the results were nearly equal as | >>before. | > | >I don't think you're going to get much better results on the Atom. I | >have an MSI Nettop box with the dual-core version and I saw about the | >same results as you. | > | >What sort of scheduling deadlines are you trying to meet? | > | >Clark | Shorter it is better it would be :-) | I can also live with this results, but i wanted to make sure to get | the best out of this hardware. | | Are you running both cores on the MSI box (maybe also with | hyperthreading enabled) with this results? Oops, I have overlooked that "more than one core" detail. In this case, you have two cyclictest threads (from different executions) clashing at priority FIFO:94. That can eventually create the latencies you see. I would also suggest running the test without Hyperthreading (adjusting the number of cyclictest threads) just to see if the latencies are there in this case. Luis | In the meantime i thought also if the SMI (system management mode) | could have a bad influence. I wrote a little userspace programm | which disables global SMI bit of the ICH7 southbridge. But also no | better results. | After that i was told (thanks to Luis Claudio!) to check latency | with the kernel module hwlat_detector. The results of this module | was 0. I interpreted this that there is no SMI that causes the | latency on my ATOM system. | | Regards, | Max -- [ Luis Claudio R. Goncalves Red Hat - Realtime Team ] [ Fingerprint: 4FDD B8C4 3C59 34BD 8BE9 2696 7203 D980 A448 C8F8 ] -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
