[dpdk-dev] [PATCH v5 01/17] eal: add max SIMD bitwidth

Ruifeng Wang Ruifeng.Wang at arm.com
Wed Oct 14 10:50:42 CEST 2020


> -----Original Message-----
> From: Ciara Power <ciara.power at intel.com>
> Sent: Tuesday, October 13, 2020 7:04 PM
> To: dev at dpdk.org
> Cc: viktorin at rehivetech.com; Ruifeng Wang <Ruifeng.Wang at arm.com>;
> jerinj at marvell.com; drc at linux.vnet.ibm.com; bruce.richardson at intel.com;
> konstantin.ananyev at intel.com; Ciara Power <ciara.power at intel.com>;
> Honnappa Nagarahalli <Honnappa.Nagarahalli at arm.com>; Dmitry Kozlyuk
> <dmitry.kozliuk at gmail.com>; Narcisa Ana Maria Vasile
> <navasile at linux.microsoft.com>; Dmitry Malloy <dmitrym at microsoft.com>;
> Pallavi Kadam <pallavi.kadam at intel.com>; Ray Kinsella <mdr at ashroe.eu>;
> Neil Horman <nhorman at tuxdriver.com>
> Subject: [PATCH v5 01/17] eal: add max SIMD bitwidth
> 
> This patch adds a max SIMD bitwidth EAL configuration. The API allows for an
> app to set this value. It can also be set using EAL argument --force-max-simd-
> bitwidth, which will lock the value and override any modifications made by
> the app.
> 
> Each arch has a define for the default SIMD bitwidth value, this is used on EAL
> init to set the config max SIMD bitwidth.
> 
> Cc: Ruifeng Wang <ruifeng.wang at arm.com>
> Cc: Jerin Jacob <jerinj at marvell.com>
> Cc: Honnappa Nagarahalli <honnappa.nagarahalli at arm.com>
> Cc: David Christensen <drc at linux.vnet.ibm.com>
> 
> Signed-off-by: Ciara Power <ciara.power at intel.com>
> 
> ---
> v4:
>   - Used RTE_SIMD_MAX instead of UINT16_MAX.
>   - Renamed enums to better reflect usage.
>   - Added functions to windows symbol export file.
>   - Modified Doxygen comments.
>   - Modified enum name.
>   - Changed RTE_SIMD_MAX value to a power of 2.
>   - Merged patch 2 into this patch.
>   - Enum now used for default value defines.
>   - Fixed some small comments on v3.
> v3:
>   - Added enum value to essentially disable using max SIMD to choose
>     paths, intended for use by ARM SVE.
>   - Fixed parsing bitwidth argument to return an error for values
>     greater than uint16_t.
>   - Removed unnecessary define in generic rte_vect.h
>   - Changed default bitwidth for ARM to UINT16_MAX, to allow for SVE.
> v2:
>   - Added to Doxygen comment for API.
>   - Changed default bitwidth for Arm to 128.
> ---
>  lib/librte_eal/arm/include/rte_vect.h      |  2 +
>  lib/librte_eal/common/eal_common_options.c | 66
> ++++++++++++++++++++++
>  lib/librte_eal/common/eal_internal_cfg.h   |  8 +++
>  lib/librte_eal/common/eal_options.h        |  2 +
>  lib/librte_eal/include/rte_eal.h           | 40 +++++++++++++
>  lib/librte_eal/ppc/include/rte_vect.h      |  2 +
>  lib/librte_eal/rte_eal_exports.def         |  2 +
>  lib/librte_eal/rte_eal_version.map         |  2 +
>  lib/librte_eal/x86/include/rte_vect.h      |  2 +
>  9 files changed, 126 insertions(+)
> 
> diff --git a/lib/librte_eal/arm/include/rte_vect.h
> b/lib/librte_eal/arm/include/rte_vect.h
> index 01c51712a1..f53c89be97 100644
> --- a/lib/librte_eal/arm/include/rte_vect.h
> +++ b/lib/librte_eal/arm/include/rte_vect.h
> @@ -14,6 +14,8 @@
>  extern "C" {
>  #endif
> 
> +#define RTE_DEFAULT_SIMD_BITWIDTH RTE_SIMD_MAX
> +
>  typedef int32x4_t xmm_t;
> 
>  #define	XMM_SIZE	(sizeof(xmm_t))
> diff --git a/lib/librte_eal/common/eal_common_options.c
> b/lib/librte_eal/common/eal_common_options.c
> index a5426e1234..8c79f1b2fc 100644
> --- a/lib/librte_eal/common/eal_common_options.c
> +++ b/lib/librte_eal/common/eal_common_options.c
> @@ -35,6 +35,7 @@
>  #ifndef RTE_EXEC_ENV_WINDOWS
>  #include <rte_telemetry.h>
>  #endif
> +#include <rte_vect.h>
> 
>  #include "eal_internal_cfg.h"
>  #include "eal_options.h"
> @@ -102,6 +103,7 @@ eal_long_options[] = {
>  	{OPT_MATCH_ALLOCATIONS, 0, NULL,
> OPT_MATCH_ALLOCATIONS_NUM},
>  	{OPT_TELEMETRY,         0, NULL, OPT_TELEMETRY_NUM        },
>  	{OPT_NO_TELEMETRY,      0, NULL, OPT_NO_TELEMETRY_NUM     },
> +	{OPT_FORCE_MAX_SIMD_BITWIDTH, 1, NULL,
> +OPT_FORCE_MAX_SIMD_BITWIDTH_NUM},
>  	{0,                     0, NULL, 0                        }
>  };
> 
> @@ -343,6 +345,8 @@ eal_reset_internal_config(struct internal_config
> *internal_cfg)
>  	internal_cfg->user_mbuf_pool_ops_name = NULL;
>  	CPU_ZERO(&internal_cfg->ctrl_cpuset);
>  	internal_cfg->init_complete = 0;
> +	internal_cfg->max_simd_bitwidth.bitwidth =
> RTE_DEFAULT_SIMD_BITWIDTH;
> +	internal_cfg->max_simd_bitwidth.forced = 0;
>  }
> 
>  static int
> @@ -1309,6 +1313,34 @@ eal_parse_iova_mode(const char *name)
>  	return 0;
>  }
> 
> +static int
> +eal_parse_simd_bitwidth(const char *arg) {
> +	char *end;
> +	unsigned long bitwidth;
> +	int ret;
> +	struct internal_config *internal_conf =
> +		eal_get_internal_configuration();
> +
> +	if (arg == NULL || arg[0] == '\0')
> +		return -1;
> +
> +	errno = 0;
> +	bitwidth = strtoul(arg, &end, 0);
> +
> +	/* check for errors */
> +	if (errno != 0 || end == NULL || *end != '\0' || bitwidth >
> RTE_SIMD_MAX)
> +		return -1;
> +
> +	if (bitwidth == 0)
> +		bitwidth = (unsigned long) RTE_SIMD_MAX;
> +	ret = rte_set_max_simd_bitwidth(bitwidth);
> +	if (ret < 0)
> +		return -1;
> +	internal_conf->max_simd_bitwidth.forced = 1;
> +	return 0;
> +}
> +
>  static int
>  eal_parse_base_virtaddr(const char *arg)  { @@ -1707,6 +1739,13 @@
> eal_parse_common_option(int opt, const char *optarg,
>  	case OPT_NO_TELEMETRY_NUM:
>  		conf->no_telemetry = 1;
>  		break;
> +	case OPT_FORCE_MAX_SIMD_BITWIDTH_NUM:
> +		if (eal_parse_simd_bitwidth(optarg) < 0) {
> +			RTE_LOG(ERR, EAL, "invalid parameter for --"
> +					OPT_FORCE_MAX_SIMD_BITWIDTH
> "\n");
> +			return -1;
> +		}
> +		break;
> 
>  	/* don't know what to do, leave this to caller */
>  	default:
> @@ -1903,6 +1942,32 @@ eal_check_common_options(struct
> internal_config *internal_cfg)
>  	return 0;
>  }
> 
> +uint16_t
> +rte_get_max_simd_bitwidth(void)
> +{
> +	const struct internal_config *internal_conf =
> +		eal_get_internal_configuration();
> +	return internal_conf->max_simd_bitwidth.bitwidth;
> +}
> +
> +int
> +rte_set_max_simd_bitwidth(uint16_t bitwidth) {
> +	struct internal_config *internal_conf =
> +		eal_get_internal_configuration();
> +	if (internal_conf->max_simd_bitwidth.forced) {
> +		RTE_LOG(NOTICE, EAL, "Cannot set max SIMD bitwidth - user
> runtime override enabled");
> +		return -EPERM;
> +	}
> +
> +	if (bitwidth < RTE_SIMD_DISABLED || !rte_is_power_of_2(bitwidth))
> {
> +		RTE_LOG(ERR, EAL, "Invalid bitwidth value!\n");
> +		return -EINVAL;
> +	}
> +	internal_conf->max_simd_bitwidth.bitwidth = bitwidth;
> +	return 0;
> +}
> +
>  void
>  eal_common_usage(void)
>  {
> @@ -1981,6 +2046,7 @@ eal_common_usage(void)
>  	       "  --"OPT_BASE_VIRTADDR"     Base virtual address\n"
>  	       "  --"OPT_TELEMETRY"   Enable telemetry support (on by
> default)\n"
>  	       "  --"OPT_NO_TELEMETRY"   Disable telemetry support\n"
> +	       "  --"OPT_FORCE_MAX_SIMD_BITWIDTH" Force the max SIMD
> bitwidth\n"
>  	       "\nEAL options for DEBUG use only:\n"
>  	       "  --"OPT_HUGE_UNLINK"       Unlink hugepage files after init\n"
>  	       "  --"OPT_NO_HUGE"           Use malloc instead of hugetlbfs\n"
> diff --git a/lib/librte_eal/common/eal_internal_cfg.h
> b/lib/librte_eal/common/eal_internal_cfg.h
> index 13f93388a7..0c880cbe17 100644
> --- a/lib/librte_eal/common/eal_internal_cfg.h
> +++ b/lib/librte_eal/common/eal_internal_cfg.h
> @@ -33,6 +33,12 @@ struct hugepage_info {
>  	int lock_descriptor;    /**< file descriptor for hugepage dir */
>  };
> 
> +struct simd_bitwidth {
> +	bool forced;
> +	/**< flag indicating if bitwidth is forced and can't be modified */
> +	uint16_t bitwidth; /**< bitwidth value */ };
> +
>  /**
>   * internal configuration
>   */
> @@ -85,6 +91,8 @@ struct internal_config {
>  	volatile unsigned int init_complete;
>  	/**< indicates whether EAL has completed initialization */
>  	unsigned int no_telemetry; /**< true to disable Telemetry */
> +	struct simd_bitwidth max_simd_bitwidth;
> +	/**< max simd bitwidth path to use */
>  };
> 
>  void eal_reset_internal_config(struct internal_config *internal_cfg); diff --git
> a/lib/librte_eal/common/eal_options.h
> b/lib/librte_eal/common/eal_options.h
> index 89769d48b4..ef33979664 100644
> --- a/lib/librte_eal/common/eal_options.h
> +++ b/lib/librte_eal/common/eal_options.h
> @@ -85,6 +85,8 @@ enum {
>  	OPT_TELEMETRY_NUM,
>  #define OPT_NO_TELEMETRY      "no-telemetry"
>  	OPT_NO_TELEMETRY_NUM,
> +#define OPT_FORCE_MAX_SIMD_BITWIDTH  "force-max-simd-bitwidth"
> +	OPT_FORCE_MAX_SIMD_BITWIDTH_NUM,
>  	OPT_LONG_MAX_NUM
>  };
> 
> diff --git a/lib/librte_eal/include/rte_eal.h b/lib/librte_eal/include/rte_eal.h
> index e3c2ef185e..706d3cca5a 100644
> --- a/lib/librte_eal/include/rte_eal.h
> +++ b/lib/librte_eal/include/rte_eal.h
> @@ -43,6 +43,23 @@ enum rte_proc_type_t {
>  	RTE_PROC_INVALID
>  };
> 
> +/**
> + * The max SIMD bitwidth value to limit vector path selection.
> + */
> +enum rte_max_simd {
> +	RTE_SIMD_DISABLED = 64,
> +	/**< Limits path selection to scalar, disables all vector paths. */
> +	RTE_SIMD_128 = 128,
> +	/**< Limits path selection to SSE/NEON/Altivec or below. */
> +	RTE_SIMD_256 = 256, /**< Limits path selection to AVX2 or below. */
> +	RTE_SIMD_512 = 512, /**< Limits path selection to AVX512 or below.
> */
> +	RTE_SIMD_MAX = INT16_MAX + 1,
> +	/**<
> +	 * Disables limiting by max SIMD bitwidth, allows all suitable paths.
> +	 * This value is used as it is a large number and a power of 2.
> +	 */
> +};
> +
>  /**
>   * Get the process type in a multi-process setup
>   *
> @@ -51,6 +68,29 @@ enum rte_proc_type_t {
>   */
>  enum rte_proc_type_t rte_eal_process_type(void);
> 
> +/**
> + * Get the supported SIMD bitwidth.
> + *
> + * @return
> + *   uint16_t bitwidth.
> + */
> +__rte_experimental
> +uint16_t rte_get_max_simd_bitwidth(void);
> +
> +/**
> + * Set the supported SIMD bitwidth.
> + * This API should only be called once at initialization, before EAL init.
> + *
> + * @param bitwidth
> + *   uint16_t bitwidth.
> + * @return
> + *   - 0 on success.
> + *   - -EINVAL on invalid bitwidth parameter.
> + *   - -EPERM if bitwidth is forced.
> + */
> +__rte_experimental
> +int rte_set_max_simd_bitwidth(uint16_t bitwidth);
> +
>  /**
>   * Request iopl privilege for all RPL.
>   *
> diff --git a/lib/librte_eal/ppc/include/rte_vect.h
> b/lib/librte_eal/ppc/include/rte_vect.h
> index b0545c878c..a69aabc568 100644
> --- a/lib/librte_eal/ppc/include/rte_vect.h
> +++ b/lib/librte_eal/ppc/include/rte_vect.h
> @@ -15,6 +15,8 @@
>  extern "C" {
>  #endif
> 
> +#define RTE_DEFAULT_SIMD_BITWIDTH RTE_SIMD_256
> +
>  typedef vector signed int xmm_t;
> 
>  #define	XMM_SIZE	(sizeof(xmm_t))
> diff --git a/lib/librte_eal/rte_eal_exports.def
> b/lib/librte_eal/rte_eal_exports.def
> index 7b35beb702..81e99b00d9 100644
> --- a/lib/librte_eal/rte_eal_exports.def
> +++ b/lib/librte_eal/rte_eal_exports.def
> @@ -26,6 +26,7 @@ EXPORTS
>  	rte_eal_tailq_register
>  	rte_eal_using_phys_addrs
>  	rte_free
> +	rte_get_max_simd_bitwidth
>  	rte_get_tsc_hz
>  	rte_hexdump
>  	rte_intr_rx_ctl
> @@ -62,6 +63,7 @@ EXPORTS
>  	rte_memzone_reserve_aligned
>  	rte_memzone_reserve_bounded
>  	rte_memzone_walk
> +	rte_set_max_simd_bitwidth
>  	rte_socket_id
>  	rte_strerror
>  	rte_strsplit
> diff --git a/lib/librte_eal/rte_eal_version.map
> b/lib/librte_eal/rte_eal_version.map
> index a93dea9fe6..714be49377 100644
> --- a/lib/librte_eal/rte_eal_version.map
> +++ b/lib/librte_eal/rte_eal_version.map
> @@ -400,6 +400,8 @@ EXPERIMENTAL {
>  	# added in 20.11
>  	__rte_eal_trace_generic_size_t;
>  	rte_service_lcore_may_be_active;
> +	rte_get_max_simd_bitwidth;
> +	rte_set_max_simd_bitwidth;
>  };
> 
>  INTERNAL {
> diff --git a/lib/librte_eal/x86/include/rte_vect.h
> b/lib/librte_eal/x86/include/rte_vect.h
> index df5a607623..a00d3d5a62 100644
> --- a/lib/librte_eal/x86/include/rte_vect.h
> +++ b/lib/librte_eal/x86/include/rte_vect.h
> @@ -35,6 +35,8 @@
>  extern "C" {
>  #endif
> 
> +#define RTE_DEFAULT_SIMD_BITWIDTH RTE_SIMD_256
> +
>  typedef __m128i xmm_t;
> 
>  #define	XMM_SIZE	(sizeof(xmm_t))
> --
> 2.22.0
Arm SVE may not perfectly fit into this. Because SIMD bitwidth is unknown / unconcerned by application. 
I think vector path will be taken when max SIMD bitwidth is not set to RTE_SIMD_DISABLED.

Reviewed-by: Ruifeng Wang <ruifeng.wang at arm.com>


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