jsquy...@osl.iu.edu, le Thu 06 Jan 2011 19:44:51 +0100, a écrit : > * > * \code > - * hwloc_alloc_membind_policy(topology, size, set, HWLOC_MEMBIND_DEFAULT, 0), > + * hwloc_alloc_membind_policy(topology, size, set, > + * HWLOC_MEMBIND_DEFAULT, 0); > * \endcode > * > - * which will try to allocate new data bound to the given set, possibly by > - * changing the current memory binding policy, or at worse allocate memory > - * without binding it at all. Since HWLOC_MEMBIND_STRICT is not given, this > - * will even not fail unless a mere malloc() itself would fail, i.e. ENOMEM. > - * > - * Each binding is available with a CPU set argument or a NUMA memory node > set > - * argument. The name of the latter ends with _nodeset. It is also possible > to > - * convert between CPU set and node set using ::hwloc_cpuset_to_nodeset or > - * ::hwloc_cpuset_from_nodeset.
> + * Setting this policy will cause the OS to try to bind all new memory > + * allocations to the specified set. Some operating systems will > + * dutifully change the current memory binding policy, but others will > + * simply ignore the policy (i.e., not bind new memory allocations at > + * all). Note that since HWLOC_MEMBIND_STRICT was not specified, > + * failures to bind will not be reported -- generally, only memory > + * allocation failures will be reported (e.g., even a plain malloc() > + * would have failed with ENOMEM). This is not what I meant: hwloc_alloc_membind_policy's purpose is only to allocate bound memory. It happens that hwloc_alloc_membind_policy _may_ change the process policy in order to be able to bind memory at all (when the underlying OS does not have a directed allocation primitive), but that's not necessary. If hwloc can simply call a directed allocation primitive, it will do it. If the OS doesn't support binding at all, then hwloc will just allocate memory. I'm not sure whether I should rephrase myself (which my just result to the same as what I had written previously) or let you rephrase it. > + HWLOC_MEMBIND_INTERLEAVE = 3, /**< \brief Allocate memory on > + * the given nodes in an > + * interleaved / round-robin > + * manner. The precise layout > + * of the memory across > + * multiple NUMA nodes is > + * OS/system specific. > + * Interleaving can be useful > + * when multiple threads from > + * the specified NUMA nodes > + * will be effectively > + * splitting the memory > + * amongst themselves. This is not really correct: if the threads were splitting the memory amongst themselves, FIRSTTOUCH should be used instead, to migrate pages close to where they are referenced from. I have rephrased that The rest is OK, thanks for your efforts! Samuel
