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[amdgcn] Scale number of threads/workers with VGPR usage

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2020-01-31  Kwok Cheung Yeung  <kcy@codesourcery.com>

	gcc/
	* config/gcn/mkoffload.c (process_asm): Add sgpr_count and vgpr_count
	to definition of hsa_kernel_description.  Parse assembly to find SGPR
	and VGPR count of kernel and store in hsa_kernel_description.

	libgomp/
	* plugin/plugin-gcn.c (struct hsa_kernel_description): Add sgpr_count
	and vgpr_count fields.
	(struct kernel_info): Add a field for a hsa_kernel_description.
	(run_kernel): Reduce the number of threads/workers if the requested
	number would require too many VGPRs.
	(init_basic_kernel_info): Initialize description field with
	the hsa_kernel_description entry for the kernel.
This commit is contained in:
Kwok Cheung Yeung 2020-01-31 06:53:30 -08:00
parent 6a97d9eae4
commit 5a28e2727f
4 changed files with 100 additions and 6 deletions
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6
gcc/ChangeLog
View File

@ -1,3 +1,9 @@
2020-01-31 Kwok Cheung Yeung <kcy@codesourcery.com>
* config/gcn/mkoffload.c (process_asm): Add sgpr_count and vgpr_count
to definition of hsa_kernel_description. Parse assembly to find SGPR
and VGPR count of kernel and store in hsa_kernel_description.
2020-01-31 Tamar Christina <tamar.christina@arm.com>
PR rtl-optimization/91838

67
gcc/config/gcn/mkoffload.c
View File

@ -211,12 +211,13 @@ access_check (const char *name, int mode)
static void
process_asm (FILE *in, FILE *out, FILE *cfile)
{
int fn_count = 0, var_count = 0, dims_count = 0;
struct obstack fns_os, vars_os, varsizes_os, dims_os;
int fn_count = 0, var_count = 0, dims_count = 0, regcount_count = 0;
struct obstack fns_os, vars_os, varsizes_os, dims_os, regcounts_os;
obstack_init (&fns_os);
obstack_init (&vars_os);
obstack_init (&varsizes_os);
obstack_init (&dims_os);
obstack_init (&regcounts_os);
struct oaccdims
{
@ -224,13 +225,20 @@ process_asm (FILE *in, FILE *out, FILE *cfile)
char *name;
} dim;
struct regcount
{
int sgpr_count;
int vgpr_count;
char *kernel_name;
} regcount;
/* Always add _init_array and _fini_array as kernels. */
obstack_ptr_grow (&fns_os, xstrdup ("_init_array"));
obstack_ptr_grow (&fns_os, xstrdup ("_fini_array"));
fn_count += 2;
char buf[1000];
enum { IN_CODE, IN_VARS, IN_FUNCS } state = IN_CODE;
enum { IN_CODE, IN_AMD_KERNEL_CODE_T, IN_VARS, IN_FUNCS } state = IN_CODE;
while (fgets (buf, sizeof (buf), in))
{
switch (state)
@ -243,6 +251,22 @@ process_asm (FILE *in, FILE *out, FILE *cfile)
obstack_grow (&dims_os, &dim, sizeof (dim));
dims_count++;
}
else if (sscanf (buf, " .amdgpu_hsa_kernel %ms\n",
&regcount.kernel_name) == 1)
break;
break;
}
case IN_AMD_KERNEL_CODE_T:
{
gcc_assert (regcount.kernel_name);
if (sscanf (buf, " wavefront_sgpr_count = %d\n",
&regcount.sgpr_count) == 1)
break;
else if (sscanf (buf, " workitem_vgpr_count = %d\n",
&regcount.vgpr_count) == 1)
break;
break;
}
case IN_VARS:
@ -282,19 +306,36 @@ process_asm (FILE *in, FILE *out, FILE *cfile)
state = IN_VARS;
else if (sscanf (buf, " .section .gnu.offload_funcs%c", &dummy) > 0)
state = IN_FUNCS;
else if (sscanf (buf, " .amd_kernel_code_%c", &dummy) > 0)
{
state = IN_AMD_KERNEL_CODE_T;
regcount.sgpr_count = regcount.vgpr_count = -1;
}
else if (sscanf (buf, " .section %c", &dummy) > 0
|| sscanf (buf, " .text%c", &dummy) > 0
|| sscanf (buf, " .bss%c", &dummy) > 0
|| sscanf (buf, " .data%c", &dummy) > 0
|| sscanf (buf, " .ident %c", &dummy) > 0)
state = IN_CODE;
else if (sscanf (buf, " .end_amd_kernel_code_%c", &dummy) > 0)
{
state = IN_CODE;
gcc_assert (regcount.kernel_name != NULL
&& regcount.sgpr_count >= 0
&& regcount.vgpr_count >= 0);
obstack_grow (&regcounts_os, &regcount, sizeof (regcount));
regcount_count++;
regcount.kernel_name = NULL;
regcount.sgpr_count = regcount.vgpr_count = -1;
}
if (state == IN_CODE)
if (state == IN_CODE || state == IN_AMD_KERNEL_CODE_T)
fputs (buf, out);
}
char **fns = XOBFINISH (&fns_os, char **);
struct oaccdims *dims = XOBFINISH (&dims_os, struct oaccdims *);
struct regcount *regcounts = XOBFINISH (&regcounts_os, struct regcount *);
fprintf (cfile, "#include <stdlib.h>\n");
fprintf (cfile, "#include <stdbool.h>\n\n");
@ -322,6 +363,8 @@ process_asm (FILE *in, FILE *out, FILE *cfile)
fprintf (cfile, "static const struct hsa_kernel_description {\n"
" const char *name;\n"
" int oacc_dims[3];\n"
" int sgpr_count;\n"
" int vgpr_count;\n"
"} gcn_kernels[] = {\n ");
dim.d[0] = dim.d[1] = dim.d[2] = 0;
const char *comma;
@ -329,15 +372,24 @@ process_asm (FILE *in, FILE *out, FILE *cfile)
{
/* Find if we recorded dimensions for this function. */
int *d = dim.d; /* Previously zeroed. */
int sgpr_count = 0;
int vgpr_count = 0;
for (int j = 0; j < dims_count; j++)
if (strcmp (fns[i], dims[j].name) == 0)
{
d = dims[j].d;
break;
}
for (int j = 0; j < regcount_count; j++)
if (strcmp (fns[i], regcounts[j].kernel_name) == 0)
{
sgpr_count = regcounts[j].sgpr_count;
vgpr_count = regcounts[j].vgpr_count;
break;
}
fprintf (cfile, "%s{\"%s\", {%d, %d, %d}}", comma,
fns[i], d[0], d[1], d[2]);
fprintf (cfile, "%s{\"%s\", {%d, %d, %d}, %d, %d}", comma,
fns[i], d[0], d[1], d[2], sgpr_count, vgpr_count);
free (fns[i]);
}
@ -346,7 +398,10 @@ process_asm (FILE *in, FILE *out, FILE *cfile)
obstack_free (&fns_os, NULL);
for (i = 0; i < dims_count; i++)
free (dims[i].name);
for (i = 0; i < regcount_count; i++)
free (regcounts[i].kernel_name);
obstack_free (&dims_os, NULL);
obstack_free (&regcounts_os, NULL);
}
/* Embed an object file into a C source file. */

10
libgomp/ChangeLog
View File

@ -1,3 +1,13 @@
2020-01-31 Kwok Cheung Yeung <kcy@codesourcery.com>
* plugin/plugin-gcn.c (struct hsa_kernel_description): Add sgpr_count
and vgpr_count fields.
(struct kernel_info): Add a field for a hsa_kernel_description.
(run_kernel): Reduce the number of threads/workers if the requested
number would require too many VGPRs.
(init_basic_kernel_info): Initialize description field with
the hsa_kernel_description entry for the kernel.
2020-01-29 Tobias Burnus <tobias@codesourcery.com>
PR bootstrap/93409

23
libgomp/plugin/plugin-gcn.c
View File

@ -371,6 +371,8 @@ struct hsa_kernel_description
{
const char *name;
int oacc_dims[3]; /* Only present for GCN kernels. */
int sgpr_count;
int vpgr_count;
};
/* Mkoffload uses this structure to describe an offload variable. */
@ -478,6 +480,8 @@ struct kernel_info
struct agent_info *agent;
/* The specific module where the kernel takes place. */
struct module_info *module;
/* Information provided by mkoffload associated with the kernel. */
struct hsa_kernel_description *description;
/* Mutex enforcing that at most once thread ever initializes a kernel for
use. A thread should have locked agent->module_rwlock for reading before
acquiring it. */
@ -2102,6 +2106,24 @@ run_kernel (struct kernel_info *kernel, void *vars,
struct GOMP_kernel_launch_attributes *kla,
struct goacc_asyncqueue *aq, bool module_locked)
{
GCN_DEBUG ("SGPRs: %d, VGPRs: %d\n", kernel->description->sgpr_count,
kernel->description->vpgr_count);
/* Reduce the number of threads/workers if there are insufficient
VGPRs available to run the kernels together. */
if (kla->ndim == 3 && kernel->description->vpgr_count > 0)
{
int granulated_vgprs = (kernel->description->vpgr_count + 3) & ~3;
int max_threads = (256 / granulated_vgprs) * 4;
if (kla->gdims[2] > max_threads)
{
GCN_WARNING ("Too many VGPRs required to support %d threads/workers"
" per team/gang - reducing to %d threads/workers.\n",
kla->gdims[2], max_threads);
kla->gdims[2] = max_threads;
}
}
GCN_DEBUG ("GCN launch on queue: %d:%d\n", kernel->agent->device_id,
(aq ? aq->id : 0));
GCN_DEBUG ("GCN launch attribs: gdims:[");
@ -2303,6 +2325,7 @@ init_basic_kernel_info (struct kernel_info *kernel,
kernel->agent = agent;
kernel->module = module;
kernel->name = d->name;
kernel->description = d;
if (pthread_mutex_init (&kernel->init_mutex, NULL))
{
GOMP_PLUGIN_error ("Failed to initialize a GCN kernel mutex");