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/**************************************************************************
*
* Copyright 2008 Dennis Smit
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* on the rights to use, copy, modify, merge, publish, distribute, sub
* license, and/or sell copies of the Software, and to permit persons to whom
* the Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
* AUTHORS, COPYRIGHT HOLDERS, AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
* USE OR OTHER DEALINGS IN THE SOFTWARE.
*
***************************************************************************/
/**
* @file
* CPU feature detection.
*
* @author Dennis Smit
* @author Based on the work of Eric Anholt <anholt@FreeBSD.org>
*/
#ifndef _UTIL_CPU_DETECT_H
#define _UTIL_CPU_DETECT_H
#include <stdbool.h>
#include "util/macros.h"
#include "util/u_atomic.h"
#include "util/u_thread.h"
/* Maximal cpu count for update affinity */
#define UTIL_MAX_CPUS 1024 /* this should be enough */
#ifdef __cplusplus
extern "C" {
#endif
enum cpu_family {
CPU_UNKNOWN,
CPU_AMD_ZEN1_ZEN2,
CPU_AMD_ZEN_HYGON,
CPU_AMD_ZEN3,
CPU_AMD_ZEN_NEXT,
CPU_AMD_LAST,
CPU_S390X,
};
typedef uint32_t util_affinity_mask[UTIL_MAX_CPUS / 32];
struct util_cpu_caps_t {
/**
* Number of CPUs available to the process.
*
* This will be less than or equal to \c max_cpus. This is the number of
* CPUs that are online and available to the process.
*/
int16_t nr_cpus;
/**
* Maximum number of CPUs that can be online in the system.
*
* This will be greater than or equal to \c nr_cpus. This is the number of
* CPUs installed in the system. \c nr_cpus will be less if some CPUs are
* offline.
*/
int16_t max_cpus;
enum cpu_family family;
/* Feature flags */
int x86_cpu_type;
unsigned cacheline;
unsigned has_intel:1;
unsigned has_tsc:1;
unsigned has_mmx:1;
unsigned has_mmx2:1;
unsigned has_sse:1;
unsigned has_sse2:1;
unsigned has_sse3:1;
unsigned has_ssse3:1;
unsigned has_sse4_1:1;
unsigned has_sse4_2:1;
unsigned has_popcnt:1;
unsigned has_avx:1;
unsigned has_avx2:1;
unsigned has_f16c:1;
unsigned has_fma:1;
unsigned has_3dnow:1;
unsigned has_3dnow_ext:1;
unsigned has_xop:1;
unsigned has_altivec:1;
unsigned has_vsx:1;
unsigned has_daz:1;
unsigned has_neon:1;
unsigned has_msa:1;
unsigned has_avx512f:1;
unsigned has_avx512dq:1;
unsigned has_avx512ifma:1;
unsigned has_avx512pf:1;
unsigned has_avx512er:1;
unsigned has_avx512cd:1;
unsigned has_avx512bw:1;
unsigned has_avx512vl:1;
unsigned has_avx512vbmi:1;
unsigned num_L3_caches;
unsigned num_cpu_mask_bits;
unsigned max_vector_bits;
uint16_t cpu_to_L3[UTIL_MAX_CPUS];
/* Affinity masks for each L3 cache. */
util_affinity_mask *L3_affinity_mask;
/**
* number of "big" CPUs in big.LITTLE configuration
*
* a "big" CPU is defined as anything with >= 50% the capacity of the largest CPU,
* useful for drivers determining how many and what kinds of threads to use
* example: 1x prime + 3x big + 4x little = 4x "big" cores
*
* A value of zero indicates that CPUs are homogeneous.
*/
int16_t nr_big_cpus;
};
struct _util_cpu_caps_state_t {
once_flag once_flag;
/**
* Initialized to 0 and set to non-zero with an atomic after the entire
* struct has been initialized.
*/
uint32_t detect_done;
struct util_cpu_caps_t caps;
};
#define U_CPU_INVALID_L3 0xffff
static inline ATTRIBUTE_CONST const struct util_cpu_caps_t *
util_get_cpu_caps(void)
{
extern void _util_cpu_detect_once(void);
extern struct _util_cpu_caps_state_t _util_cpu_caps_state;
/* On most CPU architectures, an atomic read is simply a regular memory
* load instruction with some extra compiler magic to prevent code
* re-ordering around it. The perf impact of doing this check should be
* negligible in most cases.
*
* Also, even though it looks like a bit of a lie, we've declared this
* function with ATTRIBUTE_CONST. The GCC docs say:
*
* "Calls to functions whose return value is not affected by changes to
* the observable state of the program and that have no observable
* effects on such state other than to return a value may lend
* themselves to optimizations such as common subexpression elimination.
* Declaring such functions with the const attribute allows GCC to avoid
* emitting some calls in repeated invocations of the function with the
* same argument values."
*
* The word "observable" is important here. With the exception of a
* llvmpipe debug flag behind an environment variable and a few unit tests,
* all of which emulate worse CPUs, this function neither affects nor is
* affected by any "observable" state. It has its own internal state for
* sure, but that state is such that it appears to return exactly the same
* value with the same internal data every time.
*/
if (unlikely(!p_atomic_read(&_util_cpu_caps_state.detect_done)))
call_once(&_util_cpu_caps_state.once_flag, _util_cpu_detect_once);
return &_util_cpu_caps_state.caps;
}
#ifdef __cplusplus
}
#endif
#endif /* _UTIL_CPU_DETECT_H */
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