From ff39b8b9248bcd24bc30d64fae8085322564d8ff Mon Sep 17 00:00:00 2001 From: Julian Brown Date: Thu, 19 Sep 2019 05:26:44 -0700 Subject: [PATCH] [og9] Add 'ephemeral' parameter to GOMP_OFFLOAD_openacc_async_host2dev libgomp/ * plugin/plugin-nvptx.c (GOMP_OFFLOAD_openacc_async_host2dev): Add EPHEMERAL parameter, and FIXME function comment. (cherry picked from openacc-gcc-9-branch commit 3e8fcd5d0dafe0a83ce51c30d908de0318d13672) --- libgomp/ChangeLog.omp | 5 +++++ libgomp/plugin/plugin-nvptx.c | 13 ++++++++++++- 2 files changed, 17 insertions(+), 1 deletion(-) diff --git a/libgomp/ChangeLog.omp b/libgomp/ChangeLog.omp index 943a9e4a9333..7813760e6425 100644 --- a/libgomp/ChangeLog.omp +++ b/libgomp/ChangeLog.omp @@ -1,3 +1,8 @@ +2019-09-19 Julian Brown + + * plugin/plugin-nvptx.c (GOMP_OFFLOAD_openacc_async_host2dev): + Add EPHEMERAL parameter, and FIXME function comment. + 2019-09-18 Tobias Burnus * testsuite/libgomp.oacc-c-c++-common/parallel-dims.c: Fix dg-warning diff --git a/libgomp/plugin/plugin-nvptx.c b/libgomp/plugin/plugin-nvptx.c index 4beb3222e8f8..452415e18795 100644 --- a/libgomp/plugin/plugin-nvptx.c +++ b/libgomp/plugin/plugin-nvptx.c @@ -1868,9 +1868,20 @@ GOMP_OFFLOAD_dev2dev (int ord, void *dst, const void *src, size_t n) return true; } +/* FIXME: It is unknown whether the cuMemcpyHtoDAsync API call caches source + data before the asynchronous copy takes place. Either way there is a data + race associated with ignoring the EPHEMERAL parameter here -- either if it + is TRUE (because we are copying uncached data that may disappear before the + async copy takes place) or if it is FALSE (because the source data may be + cached/snapshotted here before it is modified by an earlier async operation, + so stale data gets copied to the target). + Neither problem has been observed in practice, so far. */ + bool GOMP_OFFLOAD_openacc_async_host2dev (int ord, void *dst, const void *src, - size_t n, struct goacc_asyncqueue *aq) + size_t n, + bool ephemeral __attribute__((unused)), + struct goacc_asyncqueue *aq) { if (!nvptx_attach_host_thread_to_device (ord) || !cuda_memcpy_sanity_check (src, dst, n)) -- 2.47.2