On 11/02/2016 12:50 PM, Jakub Jelinek wrote:
> On Wed, Nov 02, 2016 at 12:34:47PM -0700, Cesar Philippidis wrote:
>> @@ -932,9 +933,84 @@ nvptx_exec (void (*fn), size_t mapnum, void
>> **hostaddrs, void **devaddrs,
>>
>> if (seen_zero)
>> {
>> + /* See if the user provided GOMP_OPENACC_DIM environment
>> + variable to specify runtime defaults. */
>> + static int default_dims[GOMP_DIM_MAX];
>> +
>> + if (!default_dims[0])
>> + {
>
> Is this guarded by some lock, or is it just racy if multiple
> nvptx_execs are done at the same time?
>
>> + /* We only read the environment variable once. You can't
>> + change it in the middle of execution. The sytntax is
>
> syntax
>
>> + the same as for the -fopenacc-dim compilation option. */
>> + const char *env_var = getenv ("GOMP_OPENACC_DIM");
>
>> +
>> + if (CUDA_SUCCESS == cuDeviceGetAttribute
>> + (&block_size, CU_DEVICE_ATTRIBUTE_MAX_THREADS_PER_BLOCK, dev)
>> + && CUDA_SUCCESS == cuDeviceGetAttribute
>> + (&warp_size, CU_DEVICE_ATTRIBUTE_WARP_SIZE, dev)
>> + && CUDA_SUCCESS == cuDeviceGetAttribute
>> + (&dev_size, CU_DEVICE_ATTRIBUTE_MULTIPROCESSOR_COUNT, dev)
>> + && CUDA_SUCCESS == cuDeviceGetAttribute
>> + (&cpu_size, CU_DEVICE_ATTRIBUTE_MAX_THREADS_PER_MULTIPROCESSOR,
>> dev))
>
> The formatting is wrong. 1) you should use the call should be on lhs of ==,
> not rhs 2) ( should be after cuDeviceGetAttribute, not on the next line
> 3) still the lines are too long.
>
> if (cuDeviceGetAttribute (&block_size,
> CU_DEVICE_ATTRIBUTE_MAX_THREADS_PER_BLOCK,
> dev) == CUDA_SUCCESS
> && cuDeviceGetAttribute (...
>
> CU_DEVICE_ATTRIBUTE_MAX_THREADS_PER_MULTIPROCESSOR
> is still way too long, perhaps initialize a temporary const var
> to that, or use some macro like
> DEV_ATTR (MAX_THREADS_PER_MULTIPROCESSOR)
> where
> #define DEV_ATTR(x) CU_DEVICE_ATTRIBUTE_##x
>
> Otherwise LGTM.
Thanks. I've applied this version to trunk.
Cesar
2016-11-02 Cesar Philippidis <ce...@codesourcery.com>
Nathan Sidwell <nat...@acm.org>
gcc/
* config/nvptx/nvptx.c (PTX_GANG_DEFAULT): Set to zero.
libgomp/
* plugin/plugin-nvptx.c (nvptx_exec): Interrogate board attributes
to determine default geometry.
* testsuite/libgomp.oacc-c-c++-common/loop-auto-1.c: Set gang
dimension.
diff --git a/gcc/config/nvptx/nvptx.c b/gcc/config/nvptx/nvptx.c
index 80fa9ae..782bbde 100644
--- a/gcc/config/nvptx/nvptx.c
+++ b/gcc/config/nvptx/nvptx.c
@@ -4174,7 +4174,7 @@ nvptx_expand_builtin (tree exp, rtx target, rtx ARG_UNUSED (subtarget),
/* Define dimension sizes for known hardware. */
#define PTX_VECTOR_LENGTH 32
#define PTX_WORKER_LENGTH 32
-#define PTX_GANG_DEFAULT 32
+#define PTX_GANG_DEFAULT 0 /* Defer to runtime. */
/* Validate compute dimensions of an OpenACC offload or routine, fill
in non-unity defaults. FN_LEVEL indicates the level at which a
diff --git a/libgomp/plugin/plugin-nvptx.c b/libgomp/plugin/plugin-nvptx.c
index 327500c..5ee350d 100644
--- a/libgomp/plugin/plugin-nvptx.c
+++ b/libgomp/plugin/plugin-nvptx.c
@@ -45,6 +45,7 @@
#include <stdio.h>
#include <unistd.h>
#include <assert.h>
+#include <errno.h>
static const char *
cuda_error (CUresult r)
@@ -932,9 +933,88 @@ nvptx_exec (void (*fn), size_t mapnum, void **hostaddrs, void **devaddrs,
if (seen_zero)
{
+ /* See if the user provided GOMP_OPENACC_DIM environment
+ variable to specify runtime defaults. */
+ static int default_dims[GOMP_DIM_MAX];
+
+ pthread_mutex_lock (&ptx_dev_lock);
+ if (!default_dims[0])
+ {
+ /* We only read the environment variable once. You can't
+ change it in the middle of execution. The syntax is
+ the same as for the -fopenacc-dim compilation option. */
+ const char *env_var = getenv ("GOMP_OPENACC_DIM");
+ if (env_var)
+ {
+ const char *pos = env_var;
+
+ for (i = 0; *pos && i != GOMP_DIM_MAX; i++)
+ {
+ if (i && *pos++ != ':')
+ break;
+ if (*pos != ':')
+ {
+ const char *eptr;
+
+ errno = 0;
+ long val = strtol (pos, (char **)&eptr, 10);
+ if (errno || val < 0 || (unsigned)val != val)
+ break;
+ default_dims[i] = (int)val;
+ pos = eptr;
+ }
+ }
+ }
+
+ int warp_size, block_size, dev_size, cpu_size;
+ CUdevice dev = nvptx_thread()->ptx_dev->dev;
+ /* 32 is the default for known hardware. */
+ int gang = 0, worker = 32, vector = 32;
+ CUdevice_attribute cu_tpb, cu_ws, cu_mpc, cu_tpm;
+
+ cu_tpb = CU_DEVICE_ATTRIBUTE_MAX_THREADS_PER_BLOCK;
+ cu_ws = CU_DEVICE_ATTRIBUTE_WARP_SIZE;
+ cu_mpc = CU_DEVICE_ATTRIBUTE_MULTIPROCESSOR_COUNT;
+ cu_tpm = CU_DEVICE_ATTRIBUTE_MAX_THREADS_PER_MULTIPROCESSOR;
+
+ if (cuDeviceGetAttribute (&block_size, cu_tpb, dev) == CUDA_SUCCESS
+ && cuDeviceGetAttribute (&warp_size, cu_ws, dev) == CUDA_SUCCESS
+ && cuDeviceGetAttribute (&dev_size, cu_mpc, dev) == CUDA_SUCCESS
+ && cuDeviceGetAttribute (&cpu_size, cu_tpm, dev) == CUDA_SUCCESS)
+ {
+ GOMP_PLUGIN_debug (0, " warp_size=%d, block_size=%d,"
+ " dev_size=%d, cpu_size=%d\n",
+ warp_size, block_size, dev_size, cpu_size);
+ gang = (cpu_size / block_size) * dev_size;
+ worker = block_size / warp_size;
+ vector = warp_size;
+ }
+
+ /* There is no upper bound on the gang size. The best size
+ matches the hardware configuration. Logical gangs are
+ scheduled onto physical hardware. To maximize usage, we
+ should guess a large number. */
+ if (default_dims[GOMP_DIM_GANG] < 1)
+ default_dims[GOMP_DIM_GANG] = gang ? gang : 1024;
+ /* The worker size must not exceed the hardware. */
+ if (default_dims[GOMP_DIM_WORKER] < 1
+ || (default_dims[GOMP_DIM_WORKER] > worker && gang))
+ default_dims[GOMP_DIM_WORKER] = worker;
+ /* The vector size must exactly match the hardware. */
+ if (default_dims[GOMP_DIM_VECTOR] < 1
+ || (default_dims[GOMP_DIM_VECTOR] != vector && gang))
+ default_dims[GOMP_DIM_VECTOR] = vector;
+
+ GOMP_PLUGIN_debug (0, " default dimensions [%d,%d,%d]\n",
+ default_dims[GOMP_DIM_GANG],
+ default_dims[GOMP_DIM_WORKER],
+ default_dims[GOMP_DIM_VECTOR]);
+ }
+ pthread_mutex_unlock (&ptx_dev_lock);
+
for (i = 0; i != GOMP_DIM_MAX; i++)
- if (!dims[i])
- dims[i] = /* TODO */ 32;
+ if (!dims[i])
+ dims[i] = default_dims[i];
}
/* This reserves a chunk of a pre-allocated page of memory mapped on both
@@ -954,8 +1034,8 @@ nvptx_exec (void (*fn), size_t mapnum, void **hostaddrs, void **devaddrs,
mapnum * sizeof (void *));
GOMP_PLUGIN_debug (0, " %s: kernel %s: launch"
" gangs=%u, workers=%u, vectors=%u\n",
- __FUNCTION__, targ_fn->launch->fn,
- dims[0], dims[1], dims[2]);
+ __FUNCTION__, targ_fn->launch->fn, dims[GOMP_DIM_GANG],
+ dims[GOMP_DIM_WORKER], dims[GOMP_DIM_VECTOR]);
// OpenACC CUDA
//
diff --git a/libgomp/testsuite/libgomp.oacc-c-c++-common/loop-auto-1.c b/libgomp/testsuite/libgomp.oacc-c-c++-common/loop-auto-1.c
index 8a755b8..3ca9388 100644
--- a/libgomp/testsuite/libgomp.oacc-c-c++-common/loop-auto-1.c
+++ b/libgomp/testsuite/libgomp.oacc-c-c++-common/loop-auto-1.c
@@ -2,6 +2,8 @@
not optimized away at -O0, and then confuses the target assembler.
{ dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
+/* { dg-additional-options "-fopenacc-dim=32" } */
+
#include <stdio.h>
#include <openacc.h>
