Messages in this thread | | | Date | Mon, 24 Aug 2015 12:15:07 +0800 | From | Xishi Qiu <> | Subject | Re: is this a problem of numactl in RedHat7.0 ? |
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On 2015/8/22 4:53, Rik van Riel wrote:
> 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: >
user: "numactl --localalloc" wil call main() numa_set_localalloc() setpol(MPOL_DEFAULT, numa_no_nodes_ptr); set_mempolicy() syscall(__NR_set_mempolicy,mode,nmask,maxnode);
kernel: do_set_mempolicy() mpol_new() if (mode == MPOL_DEFAULT) { if (nodes && !nodes_empty(*nodes)) return ERR_PTR(-EINVAL); return NULL; // return from here }
> /* > * 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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