[dpdk-dev] [PATCH v8] eal: map PCI memory resources after hugepages

Burakov, Anatoly anatoly.burakov at intel.com
Thu Nov 13 14:44:02 CET 2014


> Why has this check been removed from here. I assume it is replaced by a
> new check in secondary processes that I see added below, but perhaps you
> could explain the reason for the change?

Sure. The reason behind that change is that we can't expect that we will get a mapping at exact same address (for whatever reasons, i.e. something else is mapped there, alignment, etc.), and in primary process, it's not an error. In other words, removing this check makes it a "best-effort" type mechanism, rather than mandates PCI resources to be mapped exactly after hugepages, exactly one after another. "Wrong" mapping will still result in failure in secondary processes, and we still are risking mapping something somewhere the secondary process can't map, but that probability is decreased because we're now asking EAL to map PCI resources closer to where we most likely have some free virtual space (as evidenced by tests being done by the original submitter of the patch).

Hope that makes sense.

Thanks,
Anatoly


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