Jeff Squyres, le Wed 05 Jan 2011 23:14:58 +0100, a écrit : > On Jan 5, 2011, at 11:20 AM, Samuel Thibault wrote: > >>> “When retrieving the binding of a memory range, this flag checks > >>> whether all its pages actually have the same binding. If the flag is > >>> not given, the binding of each page will be accumulated.” > > > > The memory nodes set to which pages are bound. For now it's only > > implemented on windows and the policy is only returned as being > > MEMBIND_BIND (because there is no smarter policy on windows actually). > > I'm not sure which policy we will want to return when several subareas > > have differing policies. > > Forgive me, I still don't understand. Here's a guess at what happens -- is > this anywhere close to correct? > > When STRICT is passed: if all pages have the same policy, the nodeset is > cleared and then the corresponding numa nodes are set, and the policy output > param is set to the correct value. If all pages don't have the same policy, > ... what happens? Is an error returned and the nodeset value is untouched / > undefined?
EXDEV, and untouched, yes. > When STRICT is not passed: the nodeset is cleared and then the corresponding > numa nodes are set, regardless of whether all pages have the same policy or > not. More precisely, if there are two pages that reside on two different numa nodes, these two nodes will be set in the bitmap. > If all nodes have the same policy, the policy output param is set to that > value. If they don't have the same value, what value is set in the policy > output param? That's precisely what I said above: I'm not sure what we want to return in that case. For now it's easy because it's only implemented on windows, which only has one policy... > Also, does your middle statement mean that hwloc_get_membind will return > ENOSYS on all systems except Windows? Yes. > >>>> What is the purpose of the IN flags argument? > >>> > >>> Answered above :) At least the STRICT flag. > >> > >> Is the STRICT flag the only flag that is allowable in all the _get_ > >> functions? > > > > THREAD/PROCESS are also allowed in the hwloc_get_membind() function > > case. Migrate and nocpubind don't make sense. > > I keep getting mixed up because both the flags and the policies are > HWLOC_MEMBIND_<foo> -- there's no name delineation between the policies and > the flags. Ah. Too bad it's a bit late to rename them for 1.1 :/ > >> If other flags are passed, are they ignored or do they cause an error? > > > > IIRC they are just ignored for now. We could easily make them cause an > > error. > > I don't think I have an opinion either way; I was just looking for > clarification. Ok. I guess returning an error would make it clearer. Samuel
