Messages in this thread | | | Date | Mon, 24 Aug 2015 14:47:10 +0100 | From | Marc Zyngier <> | Subject | Re: [PATCH] irqchip, gicv3-its, numa: Workaround for Cavium ThunderX erratum 23144 |
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On 24/08/15 14:27, Ganapatrao Kulkarni wrote: > On Mon, Aug 24, 2015 at 6:15 PM, Marc Zyngier <marc.zyngier@arm.com> wrote:
>>>>> static void its_enable_cavium_thunderx(void *data) >>>>> { >>>>> - struct its_node *its = data; >>>>> + struct its_node __maybe_unused *its = data; >>>>> >>>>> - its->flags |= ITS_FLAGS_CAVIUM_THUNDERX; >>>>> +#ifdef CONFIG_CAVIUM_ERRATUM_22375 >>>>> + its->flags |= ITS_WORKAROUND_CAVIUM_22375; >>>>> + pr_info("ITS: Enabling workaround for 22375, 24313\n"); >>>>> +#endif >>>>> + >>>>> +#ifdef CONFIG_CAVIUM_ERRATUM_23144 >>>>> + if (num_possible_nodes() > 1) { >>>>> + its->numa_node = its_get_node_thunderx(its); >>>> >>>> I'd rather see numa_node being always initialized to something useful. >>>> If you're adding numa support, why can't this be initialized via >>>> standard topology bindings? >>> IIUC, topology defines only cpu topology. >> >> Well, welcome to a much more complex system where both your CPUs and >> your IOs have some degree of affinity. This needs to be described >> properly, and not hacked on the side. > ok, will add description for the function.
I sense that you misunderstood what I meant. What I'd like to see is some topology information coming from DT, showing the relationship between a device (your ITS) and a given node (your socket). This can then be used from two purposes:
- find the optimal affinity for a MSI so that it doesn't default to a foreign node (a reasonable performance expectation), - work around implementation bugs where an LPI cannot be routed to a redistributor that is on a foreign node.
I really don't feel like adding a hack just for the second point, and I'd rather get the big picture right so that your workaround is just a special case of the generic one.
Thanks,
M. -- Jazz is not dead. It just smells funny...
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