Or a after the local thread reads it, but before it writes the new result back to *p. There is nothing to guarantee that some other thread doesn't come in and modify *p Read of a shared object, WRITE is either a strict or relaxed write of a shared object): (*p) = (*p) + a which becomes (in pseudo code, READ is either a relaxed or strict As far as the memory model is concerned, (*p) += a becomes With regard to "Does UPC guarantee atomicity for basic ops with built-in types?", theĪnswer is unequivocally no. This is just another version of the upc_flag_t discussion in Issue #10. This would bring up the "where should we put the upc_op_tĮnum?" issue, as it is currently part of the collectives library and sharing this withĪn AMO library (which would make sense) would mean they'd need some common header for With this, we could use the existing upc_op_t definitions for OP (only accepting a Void upc_amo_opT(OP, shared TYPE* p, TYPE v) TYPE upc_amo_fopT(OP, shared TYPE* p, TYPE v) Probably go for something relatively short, like: To (2): While everyone will probably have their own desired flavor of spelling, I would To expand the type and operation sets, but I think this is the minimal set that I care I understand that some implementers may want This is definitely a reduced subset from what BUPC and Cray offer. One could issue a large set of atomic OPs for high throughput. The interest in the non-fetching atomic OP is that it would be a non-blocking callįor which completion is only guaranteed by the next fence. Only care about AMOs as relaxed shared accesses. This is a good bit further down their list of priorities. While there is interest in compare-and-swap, I think To (1): I think the minimal set of types that my users are interested in is T=. Information from Lauren about her community of programmers.ġ) How full a collection of types and operations we want. Is among the SHMEM atomics, and thus made its way on to the "short list" when collecting Of atomic updates to "flag bits" (think bit-fields w/o the help of the syntax). In response to (2): The "mswap" (masked swap) is, I believe, intended to aide in implementation The user to keep track of both private and shared pointers to the same datum. "local" variants of the atomic operations will be needed to avoid potentially forcing Unless one also provides a way to convert private->shared then the Optimization, and the upc_cast() under consideration for the spec will make it MOREĬommon. Removes the "local" functions? Manual "privatization" of pointer-to-shared is a common In response to (1): How does one perform atomic operations on private pointers if one (2) I don't really "get" the mswap operator, and I can't identify any particular unique (1) I dislike the "local" versions of the atomic functions (they feel like oversweet cgi ? mode = Show q = upc f = man / xt_libintm / 80 / cat3 / amo. shtml # atomics - MTU UPC AMO Extensions : http :// org / 5-publications / proceedings_attendee_lists / 2005CD / S05_Proceedings / pages / Authors / Merkey / Merkey_paper. References : - BUPC AMO Extensions : http :// upc. I think adoption of the BUPC AMO extensions would be sufficient for my interests. 3 Spec would be a big productivity enhancement and a big step toward having a standard set of AMOs that are supported across the reference and vendor implementations. The addition of UPC AMO extensions to the 1. All the implementations vary, so I have linked some of the available documentation below. 2 UPC Spec does not currently specify atomic memory operations, however, UPC AMO extensions have been implemented by LBL, MTU, and some vendors.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |