Messages in this thread Patch in this message | | | Date | Tue, 25 May 2004 12:32:38 +0200 | From | Ingo Molnar <> | Subject | Re: Help understanding slow down |
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* Andrew Morton <akpm@osdl.org> wrote:
> But if you _are_ using poll_idle() and if your CPU is hyperthreaded > then yes, one "CPU" is going to take a performance hit from the "idle" > one.
with the patch below we will print a big fat warning. (I did not want to deny idle=poll altogether - future HT implementations might work fine with polling idle.)
Ingo
Signed-off-by: Ingo Molnar <mingo@elte.hu>
--- linux/arch/i386/kernel/process.c.orig +++ linux/arch/i386/kernel/process.c @@ -202,6 +202,10 @@ static int __init idle_setup (char *str) if (!strncmp(str, "poll", 4)) { printk("using polling idle threads.\n"); pm_idle = poll_idle; +#ifdef CONFIG_SMP + if (smp_num_siblings > 1) + printk("WARNING: polling idle and HT enabled, performance may degrade.\n"); +#endif } else if (!strncmp(str, "halt", 4)) { printk("using halt in idle threads.\n"); pm_idle = default_idle; - 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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