Add changelog entry about hipGraph support

CHANGELOG.md

@@ -22,6 +22,7 @@ Documentation for rocThrust available at
 
 ### Known issues
 * `thrust::reduce_by_key` outputs are not bit-wise reproducible, as run-to-run results for pseudo-associative reduction operators (e.g. floating-point arithmetic operators) are not deterministic on the same device.
+* Note that currently, rocThrust memory allocation is performed in such a way that most algorithmic API functions cannot be called from within hipGraphs.
 
 ## rocThrust 3.0.0 for ROCm 6.0
 

docs/hipgraph-support.rst

@@ -0,0 +1,24 @@
+.. meta::
+    :description: rocThrust documentation and API reference
+    :keywords: rocThrust, ROCm, API, reference, hipGraph
+
+.. _hipgraph-support:
+
+******************************************
+hipGraph Support
+******************************************
+Currently, rocThrust does not support the use of ``hipGraphs``. ``hipGraphs`` are not allowed to contain any synchronous
+function calls or barriers. Thrust API functions are blocking (synchronous with respect to the host) by default.
+
+Thrust does provide asynchronous versions of a number of algorithms. These are contained in the ``thrust::async`` namespace
+(see the headers in ``rocThrust/thrust/async/``). However, these algorithms operate asynchronously by returning futures.
+This approach is different from the form of asynchronous execution required within ``hipGraphs``, which must be achieved by
+issuing calls into a user-defined ``hipStream``.
+
+While it is possible to create execution policies that encourage Thrust API algorithms to execute within a user-defined stream,
+(eg. ``thrust::hip_rocprim::par.on(stream)``), this is not enough to guarentee that synchronization will not occur within
+a given algorithm. This is because some Thrust functions require execution policies to be passed in at compile time (via template
+arguments) rather than at runtime. Since streams must be created at runtime, there is no way to pass these functions a stream.
+Adding a stream argument to such functions breaks compatibility with the Thrust API.
+
+For these reasons, we recommend that you do not use hipGraphs together with rocThrust code.

docs/index.rst

@@ -25,6 +25,7 @@ The documentation is structured as follows:
 
     * :ref:`data-type-support`
     * :ref:`bitwise-repro`
+    * :ref:`hipgraph-support`
     * :ref:`api-reference`
     * :ref:`genindex`