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References: <1601647919-25312-1-git-send-email-liang.j.ma@intel.com>
<532f45c5d79b4c30a919553d322bb66e91534466.1602258833.git.anatoly.burakov@intel.com>
<d1f71095230bc5a9646de28b3177b622a1d88d24.1602258833.git.anatoly.burakov@intel.com>
In-Reply-To: <d1f71095230bc5a9646de28b3177b622a1d88d24.1602258833.git.anatoly.burakov@intel.com>
From: Jerin Jacob <jerinjacobk@gmail.com>
Date: Fri, 9 Oct 2020 21:39:08 +0530
Message-ID: <CALBAE1PaSScmM=cz44Qq=pE8mF1qYqm1jtqMOFeem5nd5_YuLA@mail.gmail.com>
To: Anatoly Burakov <anatoly.burakov@intel.com>
Cc: dpdk-dev <dev@dpdk.org>, Liang Ma <liang.j.ma@intel.com>,
Jan Viktorin <viktorin@rehivetech.com>, Ruifeng Wang <ruifeng.wang@arm.com>,
David Christensen <drc@linux.vnet.ibm.com>,
Bruce Richardson <bruce.richardson@intel.com>,
Konstantin Ananyev <konstantin.ananyev@intel.com>,
David Hunt <david.hunt@intel.com>,
Thomas Monjalon <thomas@monjalon.net>, "McDaniel,
Timothy" <timothy.mcdaniel@intel.com>,
Gage Eads <gage.eads@intel.com>, chris.macnamara@intel.com
Content-Type: text/plain; charset="UTF-8"
Subject: Re: [dpdk-dev] [PATCH v5 02/10] eal: add power management intrinsics
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On Fri, Oct 9, 2020 at 9:32 PM Anatoly Burakov
<anatoly.burakov@intel.com> wrote:
>
> From: Liang Ma <liang.j.ma@intel.com>
>
> Add two new power management intrinsics, and provide an implementation
> in eal/x86 based on UMONITOR/UMWAIT instructions. The instructions
> are implemented as raw byte opcodes because there is not yet widespread
> compiler support for these instructions.
>
> The power management instructions provide an architecture-specific
> function to either wait until a specified TSC timestamp is reached, or
> optionally wait until either a TSC timestamp is reached or a memory
> location is written to. The monitor function also provides an optional
> comparison, to avoid sleeping when the expected write has already
> happened, and no more writes are expected.
>
> For more details, please refer to Intel(R) 64 and IA-32 Architectures
> Software Developer's Manual, Volume 2.
>
> Signed-off-by: Liang Ma <liang.j.ma@intel.com>
> Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
> ---
>
> Notes:
> v5:
> - Removed return values
> - Simplified intrinsics and hardcoded C0.2 state
> - Added other arch stubs
>
> lib/librte_eal/arm/include/meson.build | 1 +
> .../arm/include/rte_power_intrinsics.h | 62 ++++++++++
> .../include/generic/rte_power_intrinsics.h | 61 ++++++++++
> lib/librte_eal/include/meson.build | 1 +
> lib/librte_eal/ppc/include/meson.build | 1 +
> .../ppc/include/rte_power_intrinsics.h | 62 ++++++++++
> lib/librte_eal/x86/include/meson.build | 1 +
> .../x86/include/rte_power_intrinsics.h | 106 ++++++++++++++++++
> 8 files changed, 295 insertions(+)
> create mode 100644 lib/librte_eal/arm/include/rte_power_intrinsics.h
> create mode 100644 lib/librte_eal/include/generic/rte_power_intrinsics.h
> create mode 100644 lib/librte_eal/ppc/include/rte_power_intrinsics.h
> create mode 100644 lib/librte_eal/x86/include/rte_power_intrinsics.h
>
> diff --git a/lib/librte_eal/arm/include/meson.build b/lib/librte_eal/arm/include/meson.build
> index 73b750a18f..c6a9f70d73 100644
> --- a/lib/librte_eal/arm/include/meson.build
> +++ b/lib/librte_eal/arm/include/meson.build
> @@ -20,6 +20,7 @@ arch_headers = files(
> 'rte_pause_32.h',
> 'rte_pause_64.h',
> 'rte_pause.h',
> + 'rte_power_intrinsics.h',
> 'rte_prefetch_32.h',
> 'rte_prefetch_64.h',
> 'rte_prefetch.h',
> diff --git a/lib/librte_eal/arm/include/rte_power_intrinsics.h b/lib/librte_eal/arm/include/rte_power_intrinsics.h
> new file mode 100644
> index 0000000000..4aad44a0b9
> --- /dev/null
> +++ b/lib/librte_eal/arm/include/rte_power_intrinsics.h
> @@ -0,0 +1,62 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2020 Intel Corporation
> + */
> +
> +#ifndef _RTE_POWER_INTRINSIC_ARM_H_
> +#define _RTE_POWER_INTRINSIC_ARM_H_
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +#include <rte_atomic.h>
> +#include <rte_common.h>
> +
> +#include "generic/rte_power_intrinsics.h"
> +
> +/**
> + * This function is not supported on ARM.
> + *
> + * @param p
> + * Address to monitor for changes. Must be aligned on an 64-byte boundary.
> + * @param expected_value
> + * Before attempting the monitoring, the `p` address may be read and compared
> + * against this value. If `value_mask` is zero, this step will be skipped.
> + * @param value_mask
> + * The 64-bit mask to use to extract current value from `p`.
> + * @param tsc_timestamp
> + * Maximum TSC timestamp to wait for.
> + *
> + * @return
> + * - 0 on success
remove return as it is a void function
> + */
> +static inline void rte_power_monitor(const volatile void *p,
> + const uint64_t expected_value, const uint64_t value_mask,
> + const uint64_t tsc_timestamp)
> +{
> + RTE_SET_USED(p);
> + RTE_SET_USED(expected_value);
> + RTE_SET_USED(value_mask);
> + RTE_SET_USED(tsc_timestamp);
> +}
> +
> +/**
> + * This function is not supported on ARM.
> + *
> + * @param tsc_timestamp
> + * Maximum TSC timestamp to wait for.
> + *
> + * @return
> + * - 1 if wakeup was due to TSC timeout expiration.
> + * - 0 if wakeup was due to other reasons.
> + */
> +static inline void rte_power_pause(const uint64_t tsc_timestamp)
> +{
> + RTE_SET_USED(tsc_timestamp);
> +}
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* _RTE_POWER_INTRINSIC_ARM_H_ */
> diff --git a/lib/librte_eal/include/generic/rte_power_intrinsics.h b/lib/librte_eal/include/generic/rte_power_intrinsics.h
> new file mode 100644
> index 0000000000..e36c1f8976
> --- /dev/null
> +++ b/lib/librte_eal/include/generic/rte_power_intrinsics.h
> @@ -0,0 +1,61 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2020 Intel Corporation
> + */
> +
> +#ifndef _RTE_POWER_INTRINSIC_H_
> +#define _RTE_POWER_INTRINSIC_H_
> +
> +#include <inttypes.h>
> +
> +/**
> + * @file
> + * Advanced power management operations.
> + *
> + * This file define APIs for advanced power management,
> + * which are architecture-dependent.
> + */
> +
> +/**
> + * Monitor specific address for changes. This will cause the CPU to enter an
> + * architecture-defined optimized power state until either the specified
> + * memory address is written to, a certain TSC timestamp is reached, or other
> + * reasons cause the CPU to wake up.
> + *
> + * Additionally, an `expected` 64-bit value and 64-bit mask are provided. If
> + * mask is non-zero, the current value pointed to by the `p` pointer will be
> + * checked against the expected value, and if they match, the entering of
> + * optimized power state may be aborted.
> + *
> + * @param p
> + * Address to monitor for changes. Must be aligned on an 64-byte boundary.
> + * @param expected_value
> + * Before attempting the monitoring, the `p` address may be read and compared
> + * against this value. If `value_mask` is zero, this step will be skipped.
> + * @param value_mask
> + * The 64-bit mask to use to extract current value from `p`.
> + * @param tsc_timestamp
> + * Maximum TSC timestamp to wait for. Note that the wait behavior is
> + * architecture-dependent.
> + *
> + * @return
> + * - 0 on success
> + * - -ENOTSUP if not supported
> + */
> +static inline void rte_power_monitor(const volatile void *p,
> + const uint64_t expected_value, const uint64_t value_mask,
> + const uint64_t tsc_timestamp);
> +
> +/**
> + * Enter an architecture-defined optimized power state until a certain TSC
> + * timestamp is reached.
> + *
> + * @param tsc_timestamp
> + * Maximum TSC timestamp to wait for. Note that the wait behavior is
> + * architecture-dependent.
> + *
> + * @return
> + * Architecture-dependent return value.
> + */
> +static inline void rte_power_pause(const uint64_t tsc_timestamp);
> +
> +#endif /* _RTE_POWER_INTRINSIC_H_ */
> diff --git a/lib/librte_eal/include/meson.build b/lib/librte_eal/include/meson.build
> index cd09027958..3a12e87e19 100644
> --- a/lib/librte_eal/include/meson.build
> +++ b/lib/librte_eal/include/meson.build
> @@ -60,6 +60,7 @@ generic_headers = files(
> 'generic/rte_memcpy.h',
> 'generic/rte_pause.h',
> 'generic/rte_prefetch.h',
> + 'generic/rte_power_intrinsics.h',
> 'generic/rte_rwlock.h',
> 'generic/rte_spinlock.h',
> 'generic/rte_ticketlock.h',
> diff --git a/lib/librte_eal/ppc/include/meson.build b/lib/librte_eal/ppc/include/meson.build
> index ab4bd28092..0873b2aecb 100644
> --- a/lib/librte_eal/ppc/include/meson.build
> +++ b/lib/librte_eal/ppc/include/meson.build
> @@ -10,6 +10,7 @@ arch_headers = files(
> 'rte_io.h',
> 'rte_memcpy.h',
> 'rte_pause.h',
> + 'rte_power_intrinsics.h',
> 'rte_prefetch.h',
> 'rte_rwlock.h',
> 'rte_spinlock.h',
> diff --git a/lib/librte_eal/ppc/include/rte_power_intrinsics.h b/lib/librte_eal/ppc/include/rte_power_intrinsics.h
> new file mode 100644
> index 0000000000..70fd7b094f
> --- /dev/null
> +++ b/lib/librte_eal/ppc/include/rte_power_intrinsics.h
> @@ -0,0 +1,62 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2020 Intel Corporation
> + */
> +
> +#ifndef _RTE_POWER_INTRINSIC_PPC_H_
> +#define _RTE_POWER_INTRINSIC_PPC_H_
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +#include <rte_atomic.h>
> +#include <rte_common.h>
> +
> +#include "generic/rte_power_intrinsics.h"
> +
> +/**
> + * This function is not supported on PPC64.
> + *
> + * @param p
> + * Address to monitor for changes. Must be aligned on an 64-byte boundary.
> + * @param expected_value
> + * Before attempting the monitoring, the `p` address may be read and compared
> + * against this value. If `value_mask` is zero, this step will be skipped.
> + * @param value_mask
> + * The 64-bit mask to use to extract current value from `p`.
> + * @param tsc_timestamp
> + * Maximum TSC timestamp to wait for.
> + *
> + * @return
> + * - 0 on success
> + */
> +static inline void rte_power_monitor(const volatile void *p,
> + const uint64_t expected_value, const uint64_t value_mask,
> + const uint64_t tsc_timestamp)
> +{
> + RTE_SET_USED(p);
> + RTE_SET_USED(expected_value);
> + RTE_SET_USED(value_mask);
> + RTE_SET_USED(tsc_timestamp);
> +}
> +
> +/**
> + * This function is not supported on PPC64.
> + *
> + * @param tsc_timestamp
> + * Maximum TSC timestamp to wait for.
> + *
> + * @return
> + * - 1 if wakeup was due to TSC timeout expiration.
> + * - 0 if wakeup was due to other reasons.
> + */
> +static inline void rte_power_pause(const uint64_t tsc_timestamp)
> +{
> + RTE_SET_USED(tsc_timestamp);
> +}
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* _RTE_POWER_INTRINSIC_PPC_H_ */
> diff --git a/lib/librte_eal/x86/include/meson.build b/lib/librte_eal/x86/include/meson.build
> index f0e998c2fe..494a8142a2 100644
> --- a/lib/librte_eal/x86/include/meson.build
> +++ b/lib/librte_eal/x86/include/meson.build
> @@ -13,6 +13,7 @@ arch_headers = files(
> 'rte_io.h',
> 'rte_memcpy.h',
> 'rte_prefetch.h',
> + 'rte_power_intrinsics.h',
> 'rte_pause.h',
> 'rte_rtm.h',
> 'rte_rwlock.h',
> diff --git a/lib/librte_eal/x86/include/rte_power_intrinsics.h b/lib/librte_eal/x86/include/rte_power_intrinsics.h
> new file mode 100644
> index 0000000000..8d579eaf64
> --- /dev/null
> +++ b/lib/librte_eal/x86/include/rte_power_intrinsics.h
> @@ -0,0 +1,106 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2020 Intel Corporation
> + */
> +
> +#ifndef _RTE_POWER_INTRINSIC_X86_64_H_
> +#define _RTE_POWER_INTRINSIC_X86_64_H_
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +#include <rte_atomic.h>
> +#include <rte_common.h>
> +
> +#include "generic/rte_power_intrinsics.h"
> +
> +/**
> + * Monitor specific address for changes. This will cause the CPU to enter an
> + * architecture-defined optimized power state until either the specified
> + * memory address is written to, a certain TSC timestamp is reached, or other
> + * reasons cause the CPU to wake up.
> + *
> + * Additionally, an `expected` 64-bit value and 64-bit mask are provided. If
> + * mask is non-zero, the current value pointed to by the `p` pointer will be
> + * checked against the expected value, and if they match, the entering of
> + * optimized power state may be aborted.
> + *
> + * This function uses UMONITOR/UMWAIT instructions and will enter C0.2 state.
> + * For more information about usage of these instructions, please refer to
> + * Intel(R) 64 and IA-32 Architectures Software Developer's Manual.
> + *
> + * @param p
> + * Address to monitor for changes. Must be aligned on an 64-byte boundary.
> + * @param expected_value
> + * Before attempting the monitoring, the `p` address may be read and compared
> + * against this value. If `value_mask` is zero, this step will be skipped.
> + * @param value_mask
> + * The 64-bit mask to use to extract current value from `p`.
> + * @param tsc_timestamp
> + * Maximum TSC timestamp to wait for.
> + *
> + * @return
> + * - 0 on success
> + */
> +static inline void rte_power_monitor(const volatile void *p,
> + const uint64_t expected_value, const uint64_t value_mask,
> + const uint64_t tsc_timestamp)
> +{
> + const uint32_t tsc_l = (uint32_t)tsc_timestamp;
> + const uint32_t tsc_h = (uint32_t)(tsc_timestamp >> 32);
> + /*
> + * we're using raw byte codes for now as only the newest compiler
> + * versions support this instruction natively.
> + */
> +
> + /* set address for UMONITOR */
> + asm volatile(".byte 0xf3, 0x0f, 0xae, 0xf7;"
> + :
> + : "D"(p));
> +
> + if (value_mask) {
> + const uint64_t cur_value = *(const volatile uint64_t *)p;
> + const uint64_t masked = cur_value & value_mask;
> + /* if the masked value is already matching, abort */
> + if (masked == expected_value)
> + return;
> + }
> + /* execute UMWAIT */
> + asm volatile(".byte 0xf2, 0x0f, 0xae, 0xf7;"
> + : /* ignore rflags */
> + : "D"(0), /* enter C0.2 */
> + "a"(tsc_l), "d"(tsc_h));
> +}
> +
> +/**
> + * Enter an architecture-defined optimized power state until a certain TSC
> + * timestamp is reached.
> + *
> + * This function uses TPAUSE instruction and will enter C0.2 state. For more
> + * information about usage of this instruction, please refer to Intel(R) 64 and
> + * IA-32 Architectures Software Developer's Manual.
> + *
> + * @param tsc_timestamp
> + * Maximum TSC timestamp to wait for.
> + *
> + * @return
> + * - 1 if wakeup was due to TSC timeout expiration.
> + * - 0 if wakeup was due to other reasons.
> + */
> +static inline void rte_power_pause(const uint64_t tsc_timestamp)
> +{
> + const uint32_t tsc_l = (uint32_t)tsc_timestamp;
> + const uint32_t tsc_h = (uint32_t)(tsc_timestamp >> 32);
> +
> + /* execute TPAUSE */
> + asm volatile(".byte 0x66, 0x0f, 0xae, 0xf7;"
> + : /* ignore rflags */
> + : "D"(0), /* enter C0.2 */
> + "a"(tsc_l), "d"(tsc_h));
> +}
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* _RTE_POWER_INTRINSIC_X86_64_H_ */
> --
> 2.17.1