IRIX Base Documentation 2001 May/SGI IRIX Base Documentation 2001 May.iso/usr/share/catman/p_man/cat3/standard/sync.z/sync

Text File | 1998-10-30 | 13.9 KB | 331 lines

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SSSSYYYYNNNNCCCC((((3333CCCC))))                                                              SSSSYYYYNNNNCCCC((((3333CCCC))))



NNNNAAAAMMMMEEEE
     sync: __synchronize, __fetch_and_add, __fetch_and_sub, __fetch_and_or,
     __fetch_and_and, __fetch_and_xor, __fetch_and_nand, __add_and_fetch,
     __sub_and_fetch, __or_and_fetch, __and_and_fetch, __xor_and_fetch,
     __nand_and_fetch, __lock_test_and_set, __lock_release- C synchronization
     primitives for multiprocessing

SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
     See summaries below


DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
     The intrinsics described here provide a variety of primitive
     synchronization operations. Besides performing the particular
     synchronization operation, each of these intrinsics has two key
     properties:

         The function performed is guaranteed to be atomic (typically achieved
         by implementing the operation using a sequence of load-linked/store-
         conditional instructions in a loop).

         Associated with each instrinsic are certain _m_e_m_o_r_y _b_a_r_r_i_e_r properties
         that restrict the movement of memory references to _v_i_s_i_b_l_e _d_a_t_a
         across the intrinsic operation (by either the compiler or the
         processor).

         A visible memory reference is a reference to a data object
         potentially accessible by another thread executing in the same shared
         address space. A visible data object may be one of the following:

             C/C++ global data

             Fortran COMMON data

             data declared _e_x_t_e_r_n

             volatile data

             static data (either file-scope or function-scope)

             data accessible via function parameters

             automatic data (local-scope) that has had its address taken and
             assigned to some object which is visible (recursively).


         The memory barrier semantics of an intrinsic may be one of the
         following three types:

             aaaaccccqqqquuuuiiiirrrreeee bbbbaaaarrrrrrrriiiieeeerrrr

             Disallows the movement of memory references to visible data from



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SSSSYYYYNNNNCCCC((((3333CCCC))))                                                              SSSSYYYYNNNNCCCC((((3333CCCC))))



             after the intrinsic (in program order) to before the intrinsic
             (this behavior is desirable at lock-acquire operations, hence the
             name).


             rrrreeeelllleeeeaaaasssseeee bbbbaaaarrrrrrrriiiieeeerrrr

             Disallows the movement of memory references to visible data from
             before the intrinsic (in program order) to after the intrinsic
             (this behavior is desirable at lock-release operations, hence the
             name).

             ffffuuuullllllll bbbbaaaarrrrrrrriiiieeeerrrr

             disallows the movement of memory references to visible data past
             the intrinsic (in either direction), and is thus both an acquire
             and a release barrier. A barrier only restricts the movement of
             memory references to visible data across the intrinsic operation:
             between synchronization operations (or in their absence), memory
             references to visible data may be freely reordered subject to the
             usual data-dependence constraints.

     CCCCaaaauuuuttttiiiioooonnnn:::: Conditional execution of a synchronization intrinsic (such as
     within a _i_f or a _w_h_i_l_e statement) does not prevent the movement of memory
     references to visible data past the overall _i_f or _w_h_i_l_e construct.


     AAAAttttoooommmmiiiicccc ffffeeeettttcccchhhh----aaaannnndddd----oooopppp OOOOppppeeeerrrraaaattttiiiioooonnnnssss

     ttttyyyyppppeeee ________ffffeeeettttcccchhhh____aaaannnndddd____aaaadddddddd ((((ttttyyyyppppeeee**** ppppttttrrrr,,,, ttttyyyyppppeeee vvvvaaaalllluuuueeee,,,, ............))))

     ttttyyyyppppeeee ________ffffeeeettttcccchhhh____aaaannnndddd____ssssuuuubbbb ((((ttttyyyyppppeeee**** ppppttttrrrr,,,, ttttyyyyppppeeee vvvvaaaalllluuuueeee,,,, ............))))

     ttttyyyyppppeeee ________ffffeeeettttcccchhhh____aaaannnndddd____oooorrrr  ((((ttttyyyyppppeeee**** ppppttttrrrr,,,, ttttyyyyppppeeee vvvvaaaalllluuuueeee,,,, ............))))

     ttttyyyyppppeeee ________ffffeeeettttcccchhhh____aaaannnndddd____aaaannnndddd ((((ttttyyyyppppeeee**** ppppttttrrrr,,,, ttttyyyyppppeeee vvvvaaaalllluuuueeee,,,, ............))))

     ttttyyyyppppeeee ________ffffeeeettttcccchhhh____aaaannnndddd____xxxxoooorrrr ((((ttttyyyyppppeeee**** ppppttttrrrr,,,, ttttyyyyppppeeee vvvvaaaalllluuuueeee,,,, ............))))

     ttttyyyyppppeeee ________ffffeeeettttcccchhhh____aaaannnndddd____nnnnaaaannnndddd((((ttttyyyyppppeeee**** ppppttttrrrr,,,, ttttyyyyppppeeee vvvvaaaalllluuuueeee,,,, ............))))

         Where ttttyyyyppppeeee may be one of _i_n_t, _l_o_n_g, _l_o_n_g _l_o_n_g, _u_n_s_i_g_n_e_d _i_n_t, _u_n_s_i_g_n_e_d
         _l_o_n_g, or _u_n_s_i_g_n_e_d _l_o_n_g _l_o_n_g.
         The ellipses (...) refers to an optional list of variables protected
         by the memory barrier.

         Behavior:

             Atomically performs the specified operation with the given value
             on *ptr, and returns the old value of *ptr. (i.e.)

                 { tmp = *ptr; *ptr <op>= value; return tmp; }



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SSSSYYYYNNNNCCCC((((3333CCCC))))                                                              SSSSYYYYNNNNCCCC((((3333CCCC))))



             Full barrier.



     AAAAttttoooommmmiiiicccc oooopppp----aaaannnndddd----ffffeeeettttcccchhhh OOOOppppeeeerrrraaaattttiiiioooonnnnssss

     ttttyyyyppppeeee ________aaaadddddddd____aaaannnndddd____ffffeeeettttcccchhhh ((((ttttyyyyppppeeee**** ppppttttrrrr,,,, ttttyyyyppppeeee vvvvaaaalllluuuueeee,,,, ............))))

     ttttyyyyppppeeee ________ssssuuuubbbb____aaaannnndddd____ffffeeeettttcccchhhh ((((ttttyyyyppppeeee**** ppppttttrrrr,,,, ttttyyyyppppeeee vvvvaaaalllluuuueeee,,,, ............))))

     ttttyyyyppppeeee ________oooorrrr____aaaannnndddd____ffffeeeettttcccchhhh  ((((ttttyyyyppppeeee**** ppppttttrrrr,,,, ttttyyyyppppeeee vvvvaaaalllluuuueeee,,,, ............))))

     ttttyyyyppppeeee ________aaaannnndddd____aaaannnndddd____ffffeeeettttcccchhhh ((((ttttyyyyppppeeee**** ppppttttrrrr,,,, ttttyyyyppppeeee vvvvaaaalllluuuueeee,,,, ............))))

     ttttyyyyppppeeee ________xxxxoooorrrr____aaaannnndddd____ffffeeeettttcccchhhh ((((ttttyyyyppppeeee**** ppppttttrrrr,,,, ttttyyyyppppeeee vvvvaaaalllluuuueeee,,,, ............))))

     ttttyyyyppppeeee ________nnnnaaaannnndddd____aaaannnndddd____ffffeeeettttcccchhhh((((ttttyyyyppppeeee**** ppppttttrrrr,,,, ttttyyyyppppeeee vvvvaaaalllluuuueeee,,,, ............))))

         Where ttttyyyyppppeeee may be one of _i_n_t, _l_o_n_g, _l_o_n_g _l_o_n_g, _u_n_s_i_g_n_e_d _i_n_t, _u_n_s_i_g_n_e_d
         _l_o_n_g, or _u_n_s_i_g_n_e_d _l_o_n_g _l_o_n_g. The ellipses (...) refers to an optional
         list of variables protected by the memory barrier.

         Behavior:

             Atomically performs the specified operation with the given value
             on *ptr, and returns the new value of *ptr. (i.e.)

                 { *ptr <op>= value; return *ptr; }

             Full barrier.


     AAAAttttoooommmmiiiicccc ccccoooommmmppppaaaarrrreeee----aaaannnndddd----sssswwwwaaaapppp OOOOppppeeeerrrraaaattttiiiioooonnnn

     iiiinnnntttt ________ccccoooommmmppppaaaarrrreeee____aaaannnndddd____sssswwwwaaaapppp ((((ttttyyyyppppeeee**** ppppttttrrrr,,,, ttttyyyyppppeeee oooollllddddvvvvaaaalllluuuueeee,,,, ttttyyyyppppeeee nnnneeeewwwwvvvvaaaalllluuuueeee,,,, ............))))

         Where ttttyyyyppppeeee may be one of _i_n_t, _l_o_n_g, _l_o_n_g _l_o_n_g, _u_n_s_i_g_n_e_d _i_n_t, _u_n_s_i_g_n_e_d
         _l_o_n_g, or _u_n_s_i_g_n_e_d _l_o_n_g _l_o_n_g. The ellipses (...) refers to an optional
         list of variables protected by the memory barrier.

         Behavior:

             Atomically do the following: compare *ptr to oldvalue. If equal,
             store the new value and return 1, otherwise return 0. (i.e.)

                 if (*ptr != oldvalue) return 0;

                 else {

                         *ptr = newvalue;

                         return 1; }



                                                                        PPPPaaaaggggeeee 4444






SSSSYYYYNNNNCCCC((((3333CCCC))))                                                              SSSSYYYYNNNNCCCC((((3333CCCC))))



             Full barrier.



     AAAAttttoooommmmiiiicccc ssssyyyynnnncccchhhhrrrroooonnnniiiizzzzeeee OOOOppppeeeerrrraaaattttiiiioooonnnn

     ________ssssyyyynnnncccchhhhrrrroooonnnniiiizzzzeeee ((((............))))

     The ellipses (...) refers to an optional list of variables protected by
     the memory barrier.

         Behavior:
             Full barrier



     AAAAttttoooommmmiiiicccc lllloooocccckkkk----tttteeeesssstttt----aaaannnndddd----sssseeeetttt OOOOppppeeeerrrraaaattttiiiioooonnnn

     ttttyyyyppppeeee ________lllloooocccckkkk____tttteeeesssstttt____aaaannnndddd____sssseeeetttt ((((ttttyyyyppppeeee**** ppppttttrrrr,,,, ttttyyyyppppeeee vvvvaaaalllluuuueeee,,,, ............))))

         Where ttttyyyyppppeeee may be one of _i_n_t, _l_o_n_g, _l_o_n_g _l_o_n_g, _u_n_s_i_g_n_e_d _i_n_t, _u_n_s_i_g_n_e_d
         _l_o_n_g, or _u_n_s_i_g_n_e_d _l_o_n_g _l_o_n_g. The ellipses (...) refers to an optional
         list of variables protected by the memory barrier.

         Behavior

             Atomically store the supplied value in *ptr and return the old
             value of *ptr. (i.e.)

                 { tmp = *ptr; *ptr = value; return tmp; }

             Acquire barrier


     AAAAttttoooommmmiiiicccc lllloooocccckkkk____rrrreeeelllleeeeaaaasssseeee OOOOppppeeeerrrraaaattttiiiioooonnnn

     vvvvooooiiiidddd ________lllloooocccckkkk____rrrreeeelllleeeeaaaasssseeee ((((ttttyyyyppppeeee**** ppppttttrrrr,,,, ............))))

         Where ttttyyyyppppeeee may be one of _i_n_t, _l_o_n_g, _l_o_n_g _l_o_n_g, _u_n_s_i_g_n_e_d _i_n_t, _u_n_s_i_g_n_e_d
         _l_o_n_g, or _u_n_s_i_g_n_e_d _l_o_n_g _l_o_n_g. The ellipses (...) refers to an optional
         list of variables protected by the memory barrier.

         Behavior:

             Set *ptr to 0.  (i.e.) { *ptr = 0 }

             Release barrier








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