PETSc version 3.17.5

PetscDeviceContextJoin

Converge a set of child contexts

Synopsis

#include "petscdevice.h" 
PetscErrorCode PetscDeviceContextJoin(PetscDeviceContext dctx, PetscInt n, PetscDeviceContextJoinMode joinMode, PetscDeviceContext **dsub)

Not Collective, Asynchronous

Input Parameters

	dctx	- A PetscDeviceContext to converge on
	n	- The number of sub contexts to converge
	joinMode	- The type of join to perform
	dsub	- The sub contexts to converge

Notes

If PetscDeviceContextFork() creates n edges from a source node which all depend on the source node, then this routine is the exact mirror. That is, it creates a node (represented in dctx) which recieves n edges (and optionally destroys them) which is dependent on the completion of all incoming edges.

If joinMode is PETSC_DEVICE_CONTEXT_JOIN_DESTROY all contexts in dsub will be destroyed by this routine. Thus all sub contexts must have been created with the dctx passed to this routine.

if joinMode is PETSC_DEVICE_CONTEXT_JOIN_NO_SYNC dctx waits for all sub contexts but the sub contexts do not wait for one another afterwards.

If joinMode is PETSC_DEVICE_CONTEXT_JOIN_SYNC all sub contexts will additionally wait on dctx after converging. This has the effect of "synchronizing" the outgoing edges.

DAG representations

If joinMode is PETSC_DEVICE_CONTEXT_JOIN_DESTROY

  time ->

  -> dctx ---------/- dctx ->
  -> dsub[0] -----/
  ->  ... -------/
  -> dsub[n-1] -/

If joinMode is PETSC_DEVICE_CONTEXT_JOIN_NO_SYNC

  time ->

  -> dctx ---------/- dctx ->
  -> dsub[0] -----/--------->
  ->  ... -------/---------->
  -> dsub[n-1] -/----------->

If joinMode is PETSC_DEVICE_CONTEXT_JOIN_SYNC

  time ->

  -> dctx ---------/- dctx -\----> dctx ------>
  -> dsub[0] -----/          \---> dsub[0] --->
  ->  ... -------/            \--> ... ------->
  -> dsub[n-1] -/              \-> dsub[n-1] ->

Level

intermediate

Location

src/sys/objects/device/interface/dcontext.cxx
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