[gcc/devel/omp/gcc-12] libgomp: Document OpenMP 'pinned' memory

[gcc/devel/omp/gcc-12] libgomp: Document OpenMP 'pinned' memory

[Thomas Schwinge]

https://gcc.gnu.org/g:165b44cd22232ba7fc16dfd457322f6c95499d01

commit 165b44cd22232ba7fc16dfd457322f6c95499d01
Author: Thomas Schwinge <thomas@codesourcery.com>
Date:   Fri Mar 24 15:14:57 2023 +0100

    libgomp: Document OpenMP 'pinned' memory
    
            libgomp/
            * libgomp.texi (AMD Radeon, nvptx): Document OpenMP 'pinned'
            memory.

Diff:
---
 libgomp/ChangeLog.omp | 5 +++++
 libgomp/libgomp.texi  | 8 ++++++++
 2 files changed, 13 insertions(+)

diff --git a/libgomp/ChangeLog.omp b/libgomp/ChangeLog.omp
index 22beccc3ee3..d8a7e476090 100644
--- a/libgomp/ChangeLog.omp
+++ b/libgomp/ChangeLog.omp
@@ -1,3 +1,8 @@
+2023-04-03  Thomas Schwinge  <thomas@codesourcery.com>
+
+	* libgomp.texi (AMD Radeon, nvptx): Document OpenMP 'pinned'
+	memory.
+
 2023-03-27  Julian Brown  <julian@codesourcery.com>
 
 	* testsuite/libgomp.c++/static-aggr-constructor-destructor-1.C: New
diff --git a/libgomp/libgomp.texi b/libgomp/libgomp.texi
index 288e0b3a8ea..6355ce2a37b 100644
--- a/libgomp/libgomp.texi
+++ b/libgomp/libgomp.texi
@@ -4456,6 +4456,9 @@ The implementation remark:
 @item OpenMP code that has a requires directive with @code{unified_address} or
       @code{unified_shared_memory} will remove any GCN device from the list of
       available devices (``host fallback'').
+@item OpenMP @emph{pinned} memory (@code{omp_atk_pinned},
+      @code{ompx_pinned_mem_alloc}, for example)
+      is allocated via @code{mmap}, @code{mlock}.
 @end itemize
 
 
@@ -4518,6 +4521,11 @@ The implementation remark:
 @item OpenMP code that has a requires directive with @code{unified_address}
       or @code{unified_shared_memory} will remove any nvptx device from the
       list of available devices (``host fallback'').
+@item OpenMP @emph{pinned} memory (@code{omp_atk_pinned},
+      @code{ompx_pinned_mem_alloc}, for example)
+      is allocated via @code{cuMemHostAlloc} (CUDA Driver API).
+      This potentially helps optimization of host <-> device data
+      transfers.
 @end itemize