Re: is this a problem of numactl in RedHat7.0 ?

[Rik van Riel]

On 08/21/2015 05:27 AM, Xishi Qiu wrote:
> I use numactl(--localalloc) tool run a test case, but it shows that
> the numa policy is prefer, I don't know why.

The kernel implements MPOL_PREFERRED and MPOL_LOCAL
in the same way. Look at this code in mpol_new(),
in mm/mempolicy.c:

        /*
         * MPOL_PREFERRED cannot be used with MPOL_F_STATIC_NODES or
         * MPOL_F_RELATIVE_NODES if the nodemask is empty (local 
allocation).
         * All other modes require a valid pointer to a non-empty nodemask.
         */
        if (mode == MPOL_PREFERRED) {
                if (nodes_empty(*nodes)) {
                        if (((flags & MPOL_F_STATIC_NODES) ||
                             (flags & MPOL_F_RELATIVE_NODES)))
                                return ERR_PTR(-EINVAL);
                }
        } else if (mode == MPOL_LOCAL) {
                if (!nodes_empty(*nodes))
                        return ERR_PTR(-EINVAL);
                mode = MPOL_PREFERRED;
        } else if (nodes_empty(*nodes))
                return ERR_PTR(-EINVAL);


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