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* [gcc/devel/omp/gcc-12] libgomp/nvptx: Prepare for reverse-offload callback handling
@ 2022-10-24 15:17 Tobias Burnus
0 siblings, 0 replies; only message in thread
From: Tobias Burnus @ 2022-10-24 15:17 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:c682c50354d95a5b118bbedb5eba8d222ada268b
commit c682c50354d95a5b118bbedb5eba8d222ada268b
Author: Tobias Burnus <tobias@codesourcery.com>
Date: Mon Oct 24 17:16:29 2022 +0200
libgomp/nvptx: Prepare for reverse-offload callback handling
This patch adds a stub 'gomp_target_rev' in the host's target.c, which will
later handle the reverse offload.
For nvptx, it adds support for forwarding the offload gomp_target_ext call
to the host by setting values in a struct on the device and querying it on
the host - invoking gomp_target_rev on the result.
include/ChangeLog:
* cuda/cuda.h (enum CUdevice_attribute): Add
CU_DEVICE_ATTRIBUTE_UNIFIED_ADDRESSING.
(CU_MEMHOSTALLOC_DEVICEMAP): Define.
(cuMemHostAlloc): Add prototype.
libgomp/ChangeLog:
* config/nvptx/icv-device.c (GOMP_DEVICE_NUM_VAR): Remove
'static' for this variable.
* config/nvptx/libgomp-nvptx.h: New file.
* config/nvptx/target.c: Include it.
(GOMP_ADDITIONAL_ICVS): Declare extern var.
(GOMP_REV_OFFLOAD_VAR): Declare var.
(GOMP_target_ext): Handle reverse offload.
* libgomp-plugin.h (GOMP_PLUGIN_target_rev): New prototype.
* libgomp-plugin.c (GOMP_PLUGIN_target_rev): New, call ...
* target.c (gomp_target_rev): ... this new stub function.
* libgomp.h (gomp_target_rev): Declare.
* libgomp.map (GOMP_PLUGIN_1.4): New; add GOMP_PLUGIN_target_rev.
* plugin/cuda-lib.def (cuMemHostAlloc): Add.
* plugin/plugin-nvptx.c: Include libgomp-nvptx.h.
(struct ptx_device): Add rev_data member.
(nvptx_open_device): Remove async_engines query, last used in
r10-304-g1f4c5b9b; add unified-address assert check.
(GOMP_OFFLOAD_get_num_devices): Claim unified address
support.
(GOMP_OFFLOAD_load_image): Free rev_fn_table if no
offload functions exist. Make offload var available
on host and device.
(rev_off_dev_to_host_cpy, rev_off_host_to_dev_cpy): New.
(GOMP_OFFLOAD_run): Handle reverse offload.
(cherry picked from commit 052dfa279f5de90b324d60cf787e821b18cf496c)
Diff:
---
include/ChangeLog.omp | 10 ++++
include/cuda/cuda.h | 3 +
libgomp/ChangeLog.omp | 30 ++++++++++
libgomp/config/nvptx/icv-device.c | 2 +-
libgomp/config/nvptx/libgomp-nvptx.h | 51 +++++++++++++++++
libgomp/config/nvptx/target.c | 54 +++++++++++++++---
libgomp/libgomp-plugin.c | 12 ++++
libgomp/libgomp-plugin.h | 7 +++
libgomp/libgomp.h | 5 ++
libgomp/libgomp.map | 5 ++
libgomp/plugin/cuda-lib.def | 1 +
libgomp/plugin/plugin-nvptx.c | 104 ++++++++++++++++++++++++++++++++---
libgomp/target.c | 19 +++++++
13 files changed, 286 insertions(+), 17 deletions(-)
diff --git a/include/ChangeLog.omp b/include/ChangeLog.omp
index 4a72c8b9af5..7c2a3fa7134 100644
--- a/include/ChangeLog.omp
+++ b/include/ChangeLog.omp
@@ -1,3 +1,13 @@
+2022-10-24 Tobias Burnus <tobias@codesourcery.com>
+
+ Backport from mainline:
+ 2022-10-24 Tobias Burnus <tobias@codesourcery.com>
+
+ * cuda/cuda.h (enum CUdevice_attribute): Add
+ CU_DEVICE_ATTRIBUTE_UNIFIED_ADDRESSING.
+ (CU_MEMHOSTALLOC_DEVICEMAP): Define.
+ (cuMemHostAlloc): Add prototype.
+
2022-10-20 Tobias Burnus <tobias@codesourcery.com>
Backport from mainline:
diff --git a/include/cuda/cuda.h b/include/cuda/cuda.h
index 8135e7c9247..062d394b95f 100644
--- a/include/cuda/cuda.h
+++ b/include/cuda/cuda.h
@@ -77,6 +77,7 @@ typedef enum {
CU_DEVICE_ATTRIBUTE_CONCURRENT_KERNELS = 31,
CU_DEVICE_ATTRIBUTE_MAX_THREADS_PER_MULTIPROCESSOR = 39,
CU_DEVICE_ATTRIBUTE_ASYNC_ENGINE_COUNT = 40,
+ CU_DEVICE_ATTRIBUTE_UNIFIED_ADDRESSING = 41,
CU_DEVICE_ATTRIBUTE_COMPUTE_CAPABILITY_MAJOR = 75,
CU_DEVICE_ATTRIBUTE_COMPUTE_CAPABILITY_MINOR = 76,
CU_DEVICE_ATTRIBUTE_MAX_REGISTERS_PER_MULTIPROCESSOR = 82
@@ -123,6 +124,7 @@ enum {
#define CU_LAUNCH_PARAM_END ((void *) 0)
#define CU_LAUNCH_PARAM_BUFFER_POINTER ((void *) 1)
#define CU_LAUNCH_PARAM_BUFFER_SIZE ((void *) 2)
+#define CU_MEMHOSTALLOC_DEVICEMAP 0x02U
enum {
CU_STREAM_DEFAULT = 0,
@@ -180,6 +182,7 @@ CUresult cuMemAlloc (CUdeviceptr *, size_t);
#define cuMemAllocHost cuMemAllocHost_v2
CUresult cuMemAllocHost (void **, size_t);
CUresult cuMemAllocManaged(CUdeviceptr *, size_t, unsigned int);
+CUresult cuMemHostAlloc (void **, size_t, unsigned int);
CUresult cuMemcpy (CUdeviceptr, CUdeviceptr, size_t);
#define cuMemcpyDtoDAsync cuMemcpyDtoDAsync_v2
CUresult cuMemcpyDtoDAsync (CUdeviceptr, CUdeviceptr, size_t, CUstream);
diff --git a/libgomp/ChangeLog.omp b/libgomp/ChangeLog.omp
index cb884aa0c83..ab340385c83 100644
--- a/libgomp/ChangeLog.omp
+++ b/libgomp/ChangeLog.omp
@@ -1,3 +1,33 @@
+2022-10-24 Tobias Burnus <tobias@codesourcery.com>
+
+ Backport from mainline:
+ 2022-10-24 Tobias Burnus <tobias@codesourcery.com>
+
+ * config/nvptx/icv-device.c (GOMP_DEVICE_NUM_VAR): Remove
+ 'static' for this variable.
+ * config/nvptx/libgomp-nvptx.h: New file.
+ * config/nvptx/target.c: Include it.
+ (GOMP_ADDITIONAL_ICVS): Declare extern var.
+ (GOMP_REV_OFFLOAD_VAR): Declare var.
+ (GOMP_target_ext): Handle reverse offload.
+ * libgomp-plugin.h (GOMP_PLUGIN_target_rev): New prototype.
+ * libgomp-plugin.c (GOMP_PLUGIN_target_rev): New, call ...
+ * target.c (gomp_target_rev): ... this new stub function.
+ * libgomp.h (gomp_target_rev): Declare.
+ * libgomp.map (GOMP_PLUGIN_1.4): New; add GOMP_PLUGIN_target_rev.
+ * plugin/cuda-lib.def (cuMemHostAlloc): Add.
+ * plugin/plugin-nvptx.c: Include libgomp-nvptx.h.
+ (struct ptx_device): Add rev_data member.
+ (nvptx_open_device): Remove async_engines query, last used in
+ r10-304-g1f4c5b9b; add unified-address assert check.
+ (GOMP_OFFLOAD_get_num_devices): Claim unified address
+ support.
+ (GOMP_OFFLOAD_load_image): Free rev_fn_table if no
+ offload functions exist. Make offload var available
+ on host and device.
+ (rev_off_dev_to_host_cpy, rev_off_host_to_dev_cpy): New.
+ (GOMP_OFFLOAD_run): Handle reverse offload.
+
2022-10-20 Tobias Burnus <tobias@codesourcery.com>
Backport from mainline:
diff --git a/libgomp/config/nvptx/icv-device.c b/libgomp/config/nvptx/icv-device.c
index 6f869beadce..eef151c23c7 100644
--- a/libgomp/config/nvptx/icv-device.c
+++ b/libgomp/config/nvptx/icv-device.c
@@ -30,7 +30,7 @@
/* This is set to the ICV values of current GPU during device initialization,
when the offload image containing this libgomp portion is loaded. */
-static volatile struct gomp_offload_icvs GOMP_ADDITIONAL_ICVS;
+volatile struct gomp_offload_icvs GOMP_ADDITIONAL_ICVS;
void
omp_set_default_device (int device_num __attribute__((unused)))
diff --git a/libgomp/config/nvptx/libgomp-nvptx.h b/libgomp/config/nvptx/libgomp-nvptx.h
new file mode 100644
index 00000000000..5da9aae2531
--- /dev/null
+++ b/libgomp/config/nvptx/libgomp-nvptx.h
@@ -0,0 +1,51 @@
+/* Copyright (C) 2022 Free Software Foundation, Inc.
+ Contributed by Tobias Burnus <tobias@codesourcery.com>.
+
+ This file is part of the GNU Offloading and Multi Processing Library
+ (libgomp).
+
+ Libgomp is free software; you can redistribute it and/or modify it
+ under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3, or (at your option)
+ any later version.
+
+ Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
+ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ more details.
+
+ Under Section 7 of GPL version 3, you are granted additional
+ permissions described in the GCC Runtime Library Exception, version
+ 3.1, as published by the Free Software Foundation.
+
+ You should have received a copy of the GNU General Public License and
+ a copy of the GCC Runtime Library Exception along with this program;
+ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+ <http://www.gnu.org/licenses/>. */
+
+/* This file contains defines and type definitions shared between the
+ nvptx target's libgomp.a and the plugin-nvptx.c, but that is only
+ needef for this target. */
+
+#ifndef LIBGOMP_NVPTX_H
+#define LIBGOMP_NVPTX_H 1
+
+#define GOMP_REV_OFFLOAD_VAR __gomp_rev_offload_var
+
+struct rev_offload {
+ uint64_t fn;
+ uint64_t mapnum;
+ uint64_t addrs;
+ uint64_t sizes;
+ uint64_t kinds;
+ int32_t dev_num;
+};
+
+#if (__SIZEOF_SHORT__ != 2 \
+ || __SIZEOF_SIZE_T__ != 8 \
+ || __SIZEOF_POINTER__ != 8)
+#error "Data-type conversion required for rev_offload"
+#endif
+
+#endif /* LIBGOMP_NVPTX_H */
+
diff --git a/libgomp/config/nvptx/target.c b/libgomp/config/nvptx/target.c
index 11108d20e15..0e79388fbba 100644
--- a/libgomp/config/nvptx/target.c
+++ b/libgomp/config/nvptx/target.c
@@ -24,9 +24,12 @@
<http://www.gnu.org/licenses/>. */
#include "libgomp.h"
+#include "libgomp-nvptx.h" /* For struct rev_offload + GOMP_REV_OFFLOAD_VAR. */
#include <limits.h>
extern int __gomp_team_num __attribute__((shared));
+extern volatile struct gomp_offload_icvs GOMP_ADDITIONAL_ICVS;
+volatile struct rev_offload *GOMP_REV_OFFLOAD_VAR;
bool
GOMP_teams4 (unsigned int num_teams_lower, unsigned int num_teams_upper,
@@ -88,16 +91,53 @@ GOMP_target_ext (int device, void (*fn) (void *), size_t mapnum,
void **hostaddrs, size_t *sizes, unsigned short *kinds,
unsigned int flags, void **depend, void **args)
{
- (void) device;
- (void) fn;
- (void) mapnum;
- (void) hostaddrs;
- (void) sizes;
- (void) kinds;
+ static int lock = 0; /* == gomp_mutex_t lock; gomp_mutex_init (&lock); */
(void) flags;
(void) depend;
(void) args;
- __builtin_unreachable ();
+
+ if (device != GOMP_DEVICE_HOST_FALLBACK
+ || fn == NULL
+ || GOMP_REV_OFFLOAD_VAR == NULL)
+ return;
+
+ gomp_mutex_lock (&lock);
+
+ GOMP_REV_OFFLOAD_VAR->mapnum = mapnum;
+ GOMP_REV_OFFLOAD_VAR->addrs = (uint64_t) hostaddrs;
+ GOMP_REV_OFFLOAD_VAR->sizes = (uint64_t) sizes;
+ GOMP_REV_OFFLOAD_VAR->kinds = (uint64_t) kinds;
+ GOMP_REV_OFFLOAD_VAR->dev_num = GOMP_ADDITIONAL_ICVS.device_num;
+
+ /* Set 'fn' to trigger processing on the host; wait for completion,
+ which is flagged by setting 'fn' back to 0 on the host. */
+ uint64_t addr_struct_fn = (uint64_t) &GOMP_REV_OFFLOAD_VAR->fn;
+#if __PTX_SM__ >= 700
+ asm volatile ("st.global.release.sys.u64 [%0], %1;"
+ : : "r"(addr_struct_fn), "r" (fn) : "memory");
+#else
+ __sync_synchronize (); /* membar.sys */
+ asm volatile ("st.volatile.global.u64 [%0], %1;"
+ : : "r"(addr_struct_fn), "r" (fn) : "memory");
+#endif
+
+#if __PTX_SM__ >= 700
+ uint64_t fn2;
+ do
+ {
+ asm volatile ("ld.acquire.sys.global.u64 %0, [%1];"
+ : "=r" (fn2) : "r" (addr_struct_fn) : "memory");
+ }
+ while (fn2 != 0);
+#else
+ /* ld.global.u64 %r64,[__gomp_rev_offload_var];
+ ld.u64 %r36,[%r64];
+ membar.sys; */
+ while (__atomic_load_n (&GOMP_REV_OFFLOAD_VAR->fn, __ATOMIC_ACQUIRE) != 0)
+ ; /* spin */
+#endif
+
+ gomp_mutex_unlock (&lock);
}
void
diff --git a/libgomp/libgomp-plugin.c b/libgomp/libgomp-plugin.c
index 9d4cc623a10..316de749f69 100644
--- a/libgomp/libgomp-plugin.c
+++ b/libgomp/libgomp-plugin.c
@@ -78,3 +78,15 @@ GOMP_PLUGIN_fatal (const char *msg, ...)
gomp_vfatal (msg, ap);
va_end (ap);
}
+
+void
+GOMP_PLUGIN_target_rev (uint64_t fn_ptr, uint64_t mapnum, uint64_t devaddrs_ptr,
+ uint64_t sizes_ptr, uint64_t kinds_ptr, int dev_num,
+ void (*dev_to_host_cpy) (void *, const void *, size_t,
+ void *),
+ void (*host_to_dev_cpy) (void *, const void *, size_t,
+ void *), void *token)
+{
+ gomp_target_rev (fn_ptr, mapnum, devaddrs_ptr, sizes_ptr, kinds_ptr, dev_num,
+ dev_to_host_cpy, host_to_dev_cpy, token);
+}
diff --git a/libgomp/libgomp-plugin.h b/libgomp/libgomp-plugin.h
index 161bea7b955..bb79ef8d9d7 100644
--- a/libgomp/libgomp-plugin.h
+++ b/libgomp/libgomp-plugin.h
@@ -121,6 +121,13 @@ extern void GOMP_PLUGIN_error (const char *, ...)
extern void GOMP_PLUGIN_fatal (const char *, ...)
__attribute__ ((noreturn, format (printf, 1, 2)));
+extern void GOMP_PLUGIN_target_rev (uint64_t, uint64_t, uint64_t, uint64_t,
+ uint64_t, int,
+ void (*) (void *, const void *, size_t,
+ void *),
+ void (*) (void *, const void *, size_t,
+ void *), void *);
+
/* Prototypes for functions implemented by libgomp plugins. */
extern const char *GOMP_OFFLOAD_get_name (void);
extern unsigned int GOMP_OFFLOAD_get_caps (void);
diff --git a/libgomp/libgomp.h b/libgomp/libgomp.h
index 83d6c8d410b..e8a410a4444 100644
--- a/libgomp/libgomp.h
+++ b/libgomp/libgomp.h
@@ -1128,6 +1128,11 @@ extern int gomp_pause_host (void);
extern void gomp_init_targets_once (void);
extern int gomp_get_num_devices (void);
extern bool gomp_target_task_fn (void *);
+extern void gomp_target_rev (uint64_t, uint64_t, uint64_t, uint64_t, uint64_t,
+ int,
+ void (*) (void *, const void *, size_t, void *),
+ void (*) (void *, const void *, size_t, void *),
+ void *);
extern void * gomp_usm_alloc (size_t size, int device_num);
extern void gomp_usm_free (void *device_ptr, int device_num);
extern bool gomp_is_usm_ptr (void *ptr);
diff --git a/libgomp/libgomp.map b/libgomp/libgomp.map
index 52424f52513..8912cde1960 100644
--- a/libgomp/libgomp.map
+++ b/libgomp/libgomp.map
@@ -630,3 +630,8 @@ GOMP_PLUGIN_1.3 {
GOMP_PLUGIN_goacc_profiling_dispatch;
GOMP_PLUGIN_goacc_thread;
} GOMP_PLUGIN_1.2;
+
+GOMP_PLUGIN_1.4 {
+ global:
+ GOMP_PLUGIN_target_rev;
+} GOMP_PLUGIN_1.3;
diff --git a/libgomp/plugin/cuda-lib.def b/libgomp/plugin/cuda-lib.def
index b6d03290f35..9b786c9f2f6 100644
--- a/libgomp/plugin/cuda-lib.def
+++ b/libgomp/plugin/cuda-lib.def
@@ -30,6 +30,7 @@ CUDA_ONE_CALL (cuLinkDestroy)
CUDA_ONE_CALL (cuMemAlloc)
CUDA_ONE_CALL (cuMemAllocHost)
CUDA_ONE_CALL (cuMemAllocManaged)
+CUDA_ONE_CALL (cuMemHostAlloc)
CUDA_ONE_CALL (cuMemcpy)
CUDA_ONE_CALL (cuMemcpyDtoDAsync)
CUDA_ONE_CALL (cuMemcpyDtoH)
diff --git a/libgomp/plugin/plugin-nvptx.c b/libgomp/plugin/plugin-nvptx.c
index 7e158cfb824..1bf22bc17a0 100644
--- a/libgomp/plugin/plugin-nvptx.c
+++ b/libgomp/plugin/plugin-nvptx.c
@@ -40,6 +40,9 @@
#include "gomp-constants.h"
#include "oacc-int.h"
+/* For struct rev_offload + GOMP_REV_OFFLOAD_VAR. */
+#include "config/nvptx/libgomp-nvptx.h"
+
#include <pthread.h>
#ifndef PLUGIN_NVPTX_INCLUDE_SYSTEM_CUDA_H
# include "cuda/cuda.h"
@@ -330,6 +333,7 @@ struct ptx_device
pthread_mutex_t lock;
} omp_stacks;
+ struct rev_offload *rev_data;
struct ptx_device *next;
};
@@ -429,7 +433,7 @@ nvptx_open_device (int n)
struct ptx_device *ptx_dev;
CUdevice dev, ctx_dev;
CUresult r;
- int async_engines, pi;
+ int pi;
CUDA_CALL_ERET (NULL, cuDeviceGet, &dev, n);
@@ -525,10 +529,12 @@ nvptx_open_device (int n)
CU_DEVICE_ATTRIBUTE_MAX_THREADS_PER_MULTIPROCESSOR, dev);
ptx_dev->max_threads_per_multiprocessor = pi;
- r = CUDA_CALL_NOCHECK (cuDeviceGetAttribute, &async_engines,
- CU_DEVICE_ATTRIBUTE_ASYNC_ENGINE_COUNT, dev);
- if (r != CUDA_SUCCESS)
- async_engines = 1;
+ /* Required below for reverse offload as implemented, but with compute
+ capability >= 2.0 and 64bit device processes, this should be universally be
+ the case; hence, an assert. */
+ r = CUDA_CALL_NOCHECK (cuDeviceGetAttribute, &pi,
+ CU_DEVICE_ATTRIBUTE_UNIFIED_ADDRESSING, dev);
+ assert (r == CUDA_SUCCESS && pi);
for (int i = 0; i != GOMP_DIM_MAX; i++)
ptx_dev->default_dims[i] = 0;
@@ -1195,7 +1201,8 @@ GOMP_OFFLOAD_get_num_devices (unsigned int omp_requires_mask)
{
int num_devices = nvptx_get_num_devices ();
/* Return -1 if no omp_requires_mask cannot be fulfilled but
- devices were present. */
+ devices were present. Unified-shared address: see comment in
+ nvptx_open_device for CU_DEVICE_ATTRIBUTE_UNIFIED_ADDRESSING. */
if (num_devices > 0
&& (omp_requires_mask & ~(GOMP_REQUIRES_UNIFIED_ADDRESS
| GOMP_REQUIRES_UNIFIED_SHARED_MEMORY)))
@@ -1414,7 +1421,7 @@ GOMP_OFFLOAD_load_image (int ord, unsigned version, const void *target_data,
else if (rev_fn_table)
{
CUdeviceptr var;
- size_t bytes;
+ size_t bytes, i;
r = CUDA_CALL_NOCHECK (cuModuleGetGlobal, &var, &bytes, module,
"$offload_func_table");
if (r != CUDA_SUCCESS)
@@ -1424,6 +1431,37 @@ GOMP_OFFLOAD_load_image (int ord, unsigned version, const void *target_data,
r = CUDA_CALL_NOCHECK (cuMemcpyDtoH, *rev_fn_table, var, bytes);
if (r != CUDA_SUCCESS)
GOMP_PLUGIN_fatal ("cuMemcpyDtoH error: %s", cuda_error (r));
+ /* Free if only NULL entries. */
+ for (i = 0; i < fn_entries; ++i)
+ if ((*rev_fn_table)[i] != 0)
+ break;
+ if (i == fn_entries)
+ {
+ free (*rev_fn_table);
+ *rev_fn_table = NULL;
+ }
+ }
+
+ if (rev_fn_table && *rev_fn_table && dev->rev_data == NULL)
+ {
+ /* cuMemHostAlloc memory is accessible on the device, if unified-shared
+ address is supported; this is assumed - see comment in
+ nvptx_open_device for CU_DEVICE_ATTRIBUTE_UNIFIED_ADDRESSING. */
+ CUDA_CALL_ASSERT (cuMemHostAlloc, (void **) &dev->rev_data,
+ sizeof (*dev->rev_data), CU_MEMHOSTALLOC_DEVICEMAP);
+ CUdeviceptr dp = (CUdeviceptr) dev->rev_data;
+ CUdeviceptr device_rev_offload_var;
+ size_t device_rev_offload_size;
+ CUresult r = CUDA_CALL_NOCHECK (cuModuleGetGlobal,
+ &device_rev_offload_var,
+ &device_rev_offload_size, module,
+ XSTRING (GOMP_REV_OFFLOAD_VAR));
+ if (r != CUDA_SUCCESS)
+ GOMP_PLUGIN_fatal ("cuModuleGetGlobal error - GOMP_REV_OFFLOAD_VAR: %s", cuda_error (r));
+ r = CUDA_CALL_NOCHECK (cuMemcpyHtoD, device_rev_offload_var, &dp,
+ sizeof (dp));
+ if (r != CUDA_SUCCESS)
+ GOMP_PLUGIN_fatal ("cuMemcpyHtoD error: %s", cuda_error (r));
}
nvptx_set_clocktick (module, dev);
@@ -2064,6 +2102,23 @@ nvptx_stacks_acquire (struct ptx_device *ptx_dev, size_t size, int num)
return (void *) ptx_dev->omp_stacks.ptr;
}
+
+void
+rev_off_dev_to_host_cpy (void *dest, const void *src, size_t size,
+ CUstream stream)
+{
+ CUDA_CALL_ASSERT (cuMemcpyDtoHAsync, dest, (CUdeviceptr) src, size, stream);
+ CUDA_CALL_ASSERT (cuStreamSynchronize, stream);
+}
+
+void
+rev_off_host_to_dev_cpy (void *dest, const void *src, size_t size,
+ CUstream stream)
+{
+ CUDA_CALL_ASSERT (cuMemcpyHtoDAsync, (CUdeviceptr) dest, src, size, stream);
+ CUDA_CALL_ASSERT (cuStreamSynchronize, stream);
+}
+
void
GOMP_OFFLOAD_run (int ord, void *tgt_fn, void *tgt_vars, void **args)
{
@@ -2098,6 +2153,8 @@ GOMP_OFFLOAD_run (int ord, void *tgt_fn, void *tgt_vars, void **args)
nvptx_adjust_launch_bounds (tgt_fn, ptx_dev, &teams, &threads);
size_t stack_size = nvptx_stacks_size ();
+ bool reverse_offload = ptx_dev->rev_data != NULL;
+ CUstream copy_stream = NULL;
pthread_mutex_lock (&ptx_dev->omp_stacks.lock);
void *stacks = nvptx_stacks_acquire (ptx_dev, stack_size, teams * threads);
@@ -2111,12 +2168,41 @@ GOMP_OFFLOAD_run (int ord, void *tgt_fn, void *tgt_vars, void **args)
GOMP_PLUGIN_debug (0, " %s: kernel %s: launch"
" [(teams: %u), 1, 1] [(lanes: 32), (threads: %u), 1]\n",
__FUNCTION__, fn_name, teams, threads);
+ if (reverse_offload)
+ CUDA_CALL_ASSERT (cuStreamCreate, ©_stream, CU_STREAM_NON_BLOCKING);
r = CUDA_CALL_NOCHECK (cuLaunchKernel, function, teams, 1, 1,
32, threads, 1, lowlat_pool_size, NULL, NULL, config);
if (r != CUDA_SUCCESS)
GOMP_PLUGIN_fatal ("cuLaunchKernel error: %s", cuda_error (r));
-
- r = CUDA_CALL_NOCHECK (cuCtxSynchronize, );
+ if (reverse_offload)
+ while (true)
+ {
+ r = CUDA_CALL_NOCHECK (cuStreamQuery, NULL);
+ if (r == CUDA_SUCCESS)
+ break;
+ if (r == CUDA_ERROR_LAUNCH_FAILED)
+ GOMP_PLUGIN_fatal ("cuStreamQuery error: %s %s\n", cuda_error (r),
+ maybe_abort_msg);
+ else if (r != CUDA_ERROR_NOT_READY)
+ GOMP_PLUGIN_fatal ("cuStreamQuery error: %s", cuda_error (r));
+
+ if (__atomic_load_n (&ptx_dev->rev_data->fn, __ATOMIC_ACQUIRE) != 0)
+ {
+ struct rev_offload *rev_data = ptx_dev->rev_data;
+ GOMP_PLUGIN_target_rev (rev_data->fn, rev_data->mapnum,
+ rev_data->addrs, rev_data->sizes,
+ rev_data->kinds, rev_data->dev_num,
+ rev_off_dev_to_host_cpy,
+ rev_off_host_to_dev_cpy, copy_stream);
+ CUDA_CALL_ASSERT (cuStreamSynchronize, copy_stream);
+ __atomic_store_n (&rev_data->fn, 0, __ATOMIC_RELEASE);
+ }
+ usleep (1);
+ }
+ else
+ r = CUDA_CALL_NOCHECK (cuCtxSynchronize, );
+ if (reverse_offload)
+ CUDA_CALL_ASSERT (cuStreamDestroy, copy_stream);
if (r == CUDA_ERROR_LAUNCH_FAILED)
GOMP_PLUGIN_fatal ("cuCtxSynchronize error: %s %s\n", cuda_error (r),
maybe_abort_msg);
diff --git a/libgomp/target.c b/libgomp/target.c
index 2a3a5fa4e4f..cbd1fc91969 100644
--- a/libgomp/target.c
+++ b/libgomp/target.c
@@ -3124,6 +3124,25 @@ GOMP_target_ext (int device, void (*fn) (void *), size_t mapnum,
htab_free (refcount_set);
}
+/* Handle reverse offload. This is called by the device plugins for a
+ reverse offload; it is not called if the outer target runs on the host. */
+
+void
+gomp_target_rev (uint64_t fn_ptr __attribute__ ((unused)),
+ uint64_t mapnum __attribute__ ((unused)),
+ uint64_t devaddrs_ptr __attribute__ ((unused)),
+ uint64_t sizes_ptr __attribute__ ((unused)),
+ uint64_t kinds_ptr __attribute__ ((unused)),
+ int dev_num __attribute__ ((unused)),
+ void (*dev_to_host_cpy) (void *, const void *, size_t,
+ void *) __attribute__ ((unused)),
+ void (*host_to_dev_cpy) (void *, const void *, size_t,
+ void *) __attribute__ ((unused)),
+ void *token __attribute__ ((unused)))
+{
+ __builtin_unreachable ();
+}
+
/* Host fallback for GOMP_target_data{,_ext} routines. */
static void
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2022-10-24 15:17 [gcc/devel/omp/gcc-12] libgomp/nvptx: Prepare for reverse-offload callback handling Tobias Burnus
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