MXM supports atomics.
On Thursday, November 6, 2014, Nathan Hjelm <hje...@lanl.gov> wrote: > I haven't look at that yet. Would be great to get the new osc component > working over both btls and mtls. I know portals supports atomics but I > don't know whether psm does. > > -Nathan > > On Thu, Nov 06, 2014 at 08:45:15PM +0200, Mike Dubman wrote: > > btw, do you plan to add atomics API to MTL layer as well? > > On Thu, Nov 6, 2014 at 5:23 PM, Nathan Hjelm <hje...@lanl.gov > <javascript:;>> wrote: > > > > At the moment I select the lowest latency BTL that can reach all of > the > > ranks in the communicator used to create the window. I can add code > to > > round-robin windows over the available BTLs on multi-rail systems. > > > > -Nathan > > On Wed, Nov 05, 2014 at 06:38:25PM -0800, Paul Hargrove wrote: > > > All atomics must be done through not just "the same btl" but > the > > same btl > > > MODULE, since atomics from two IB HCAs, for instance, are not > > necessarily > > > coherent. So, how is the "best" one to be selected? > > > > > > -Paul [Sent from my phone] > > > > > > On Nov 5, 2014 7:15 AM, "Nathan Hjelm" <hje...@lanl.gov > <javascript:;>> wrote: > > > > > > In the new osc component I don't try to handle that case. All > > atomics > > > have to be done through the same btl (including atomics on > self). > > I did > > > this because with the default setup of Gemini they can not be > > mixed. If > > > it is possible to mix them with other networks I would be > happy > > to add > > > an atomic flag for that. > > > > > > -Nathan > > > > > > On Wed, Nov 05, 2014 at 03:41:58AM -0500, Joshua Ladd wrote: > > > > Quick question. Out of curiosity, how do you handle the > > (common) > > > case of > > > > mixing network atomics with CPU atomics? Say for a > single > > target > > > with two > > > > initiators, one initiator is on host with the target, so > > goes > > > through the > > > > SM BTL, and the other initiator is off host, so goes > through > > the > > > network > > > > BTL. > > > > > > > > Josh > > > > On Tue, Nov 4, 2014 at 6:46 PM, Nathan Hjelm > > <hje...@lanl.gov <javascript:;>> > > > wrote: > > > > > > > > What: Completely revamp the BTL RDMA interface > (btl_put, > > btl_get) > > > to > > > > better match what is needed for MPI one-sided. > > > > > > > > Why: I am preparing to push an enhanced MPI-3 > one-sided > > component > > > that > > > > makes use of network rdma and atomic operations to > provide > > a fast > > > truely > > > > one-sided implementation. Before I can push this > component > > I want > > > to > > > > change the btl interface to: > > > > > > > > - Provide access to network atomic operations. I only > > need add > > > and > > > > cswap but the interface can be extended to any > number > > of > > > operations. > > > > > > > > The new interface provides three new functions: > > btl_atomic_op, > > > > btl_atomic_fop, and btl_atomic_cswap. Additionally > > there are > > > two new > > > > btl_flags to indicate available atomic support: > > > > MCA_BTL_FLAGS_ATOMIC_OPS, and > > MCA_BTL_FLAGS_ATOMIC_FOPS. The > > > > btl_atomics_flags field has been added to indicate > > which > > > atomic > > > > operations are supported (see > > mca_btl_base_atomic_op_t). At > > > this time > > > > I only added support for 64-bit integer atomics > but I > > am open > > > to > > > > adding support for 32-bit as well. > > > > > > > > - Provide an interface that will allow simultaneous > > put/get > > > operations > > > > without extra calls into the btl. The current > interface > > > requires the > > > > btl user to call prepare_src/prepare_dst before > every > > rdma > > > > operation. In some cases this is a complete waste > > (vader, sm > > > with > > > > CMA, knem, or xpmem). > > > > > > > > I seperated the registration of memory from the > segment > > info. > > > More > > > > information is provided below. The new put/get > > functions have > > > the > > > > following signatures: > > > > > > > > typedef int (*mca_btl_base_module_put_fn_t) (struct > > > > mca_btl_base_module_t *btl, > > > > struct mca_btl_base_endpoint_t *endpoint, void > > > *local_address, > > > > uint64_t remote_address, struct > > > mca_btl_base_registration_handle_t > > > > *local_handle, > > > > struct mca_btl_base_registration_handle_t > > *remote_handle, > > > size_t > > > > size, int flags, > > > > int order, mca_btl_base_rdma_completion_fn_t > cbfunc, > > void > > > > *cbcontext, void *cbdata); > > > > > > > > typedef int (*mca_btl_base_module_get_fn_t) (struct > > > > mca_btl_base_module_t *btl, > > > > struct mca_btl_base_endpoint_t *endpoint, void > > > *local_address, > > > > uint64_t remote_address, struct > > > mca_btl_base_registration_handle_t > > > > *local_handle, > > > > struct mca_btl_base_registration_handle_t > > *remote_handle, > > > size_t > > > > size, int flags, > > > > int order, mca_btl_base_rdma_completion_fn_t > cbfunc, > > void > > > > *cbcontext, void *cbdata); > > > > > > > > typedef void (*mca_btl_base_rdma_completion_fn_t)( > > > > struct mca_btl_base_module_t* module, > > > > struct mca_btl_base_endpoint_t* endpoint, > > > > void *local_address, > > > > struct mca_btl_base_registration_handle_t > > *local_handle, > > > > void *context, > > > > void *cbdata, > > > > int status); > > > > > > > > I may modify the completion function to provide > more > > > information on > > > > the completed operation (size). > > > > > > > > - Allow the registration of an entire region even if > the > > region > > > can not > > > > be modified with a single rdma operation. At this > time > > > prepare_src > > > > and prepare_dst may modify the size and register a > > smaller > > > > region. This will not work. > > > > > > > > This is done in the new interface through the new > > > btl_register_mem, > > > > and btl_deregister_mem interfaces. The > btl_register_mem > > > interface > > > > returns a registration handle of size > > > btl_registration_handle_size > > > > that can be used as either the local_handle or > > remote_handle > > > to any > > > > rdma/atomic function. BTLs that do not provide > these > > functions > > > do not > > > > require registration for rdma/atomic operations. > > > > > > > > typedef struct mca_btl_base_registration_handle_t > > > > *(*mca_btl_base_module_register_mem_fn_t)( > > > > struct mca_btl_base_module_t* btl, struct > > > mca_btl_base_endpoint_t > > > > *endpoint, void *base, > > > > size_t size, uint32_t flags); > > > > > > > > typedef struct mca_btl_base_registration_handle_t > > > > *(*mca_btl_base_module_register_mem_fn_t)( > > > > struct mca_btl_base_module_t* btl, struct > > > mca_btl_base_endpoint_t > > > > *endpoint, void *base, > > > > size_t size, uint32_t flags); > > > > > > > > - Expose the limitations of the put and get > operations so > > the > > > caller > > > > can make decisions before trying a get or put > > operation. Two > > > > examples: the Gemini interconnect has an alignment > > restriction > > > on > > > > get, openib devices may have a limit on how large a > > single > > > get/put > > > > operation can be. The current interface sort of > gives > > the put > > > limit > > > > but it is tied to the rdma pipeline protocol. > > > > > > > > This is done in the new interface by providing > > btl_get_limit, > > > > btl_get_alignment, btl_put_limit, and > > btl_put_alignment. > > > Operations > > > > that violate these restrictions should return > > > OPAL_ERR_BAD_PARAM > > > > (operation over limit) or OPAL_ERR_NOT_SUPPORTED > > (operation > > > not > > > > supported due to alignment restructions with > either the > > source > > > or > > > > destination buffer). > > > > > > > > This is a big change and I do not expect everyone to > like > > 100% of > > > these > > > > changes. I welcome any feedback people have. > > > > > > > > When: Tuesday, Nov 17, 2015. This is during SC so > there > > will be > > > time for > > > > face-to-face discussion if anyone has any concerns or > > would like > > > to see > > > > something changed. > > > > > > > > The proposed new btl interface as well as updated > versions > > of: > > > pml/ob1, > > > > btl/openib, btl/self, btl/scif, btl/sm, btl/tcp, > btl/ugni, > > and > > > btl/vader > > > > can be found in my btlmod branch at: > > > > > > > > https://github.com/hjelmn/ompi/tree/btlmod > > > > > > > > Other btls (smcuda, and usnic) still need to be > updated to > > > provide the > > > > new interface. Unmodified btl will not build. > > > > > > > > If there are no objections I will push the btl > > modifications into > > > the > > > > master two weeks from today (Nov 17). Please take a > look > > and let > > > me know > > > > what you think. > > > > > > > > _______________________________________________ > > > > devel mailing list > > > > de...@open-mpi.org <javascript:;> > > > > Subscription: > > http://www.open-mpi.org/mailman/listinfo.cgi/devel > > > > Link to this post: > > > > > > http://www.open-mpi.org/community/lists/devel/2014/11/16193.php > > > > > > > _______________________________________________ > > > > devel mailing list > > > > de...@open-mpi.org <javascript:;> > > > > Subscription: > > http://www.open-mpi.org/mailman/listinfo.cgi/devel > > > > Link to this post: > > > > http://www.open-mpi.org/community/lists/devel/2014/11/16195.php > > > > > > _______________________________________________ > > > devel mailing list > > > de...@open-mpi.org <javascript:;> > > > Subscription: > http://www.open-mpi.org/mailman/listinfo.cgi/devel > > > Link to this post: > > > > http://www.open-mpi.org/community/lists/devel/2014/11/16198.php > > > > > _______________________________________________ > > > devel mailing list > > > de...@open-mpi.org <javascript:;> > > > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/devel > > > Link to this post: > > http://www.open-mpi.org/community/lists/devel/2014/11/16224.php > > > > _______________________________________________ > > devel mailing list > > de...@open-mpi.org <javascript:;> > > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/devel > > Link to this post: > > http://www.open-mpi.org/community/lists/devel/2014/11/16230.php > > > > -- > > Kind Regards, > > M. > > > _______________________________________________ > > devel mailing list > > de...@open-mpi.org <javascript:;> > > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/devel > > Link to this post: > http://www.open-mpi.org/community/lists/devel/2014/11/16240.php > >
