Re: [PATCH v6 3/3] power: amd power monitor support

[Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>]

09.10.2023 15:05, Sivaprasad Tummala пишет:
> mwaitx allows EPYC processors to enter a implementation dependent
> power/performance optimized state (C1 state) for a specific period
> or until a store to the monitored address range.
> 
> Signed-off-by: Sivaprasad Tummala <sivaprasad.tummala@amd.com>
> Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>
> ---
>   lib/eal/x86/rte_power_intrinsics.c | 108 ++++++++++++++++++++++-------
>   1 file changed, 84 insertions(+), 24 deletions(-)
> 
> diff --git a/lib/eal/x86/rte_power_intrinsics.c b/lib/eal/x86/rte_power_intrinsics.c
> index 664cde01e9..0d2953f570 100644
> --- a/lib/eal/x86/rte_power_intrinsics.c
> +++ b/lib/eal/x86/rte_power_intrinsics.c
> @@ -17,6 +17,78 @@ static struct power_wait_status {
>   	volatile void *monitor_addr; /**< NULL if not currently sleeping */
>   } __rte_cache_aligned wait_status[RTE_MAX_LCORE];
>   
> +/**
> + * This functions 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.
> + */
> +static void intel_umonitor(volatile void *addr)
> +{
> +#if defined(RTE_TOOLCHAIN_MSVC) || defined(__WAITPKG__)
> +	/* cast away "volatile" when using the intrinsic */
> +	_umonitor((void *)(uintptr_t)addr);
> +#else
> +	/*
> +	 * we're using raw byte codes for compiler versions which
> +	 * don't support this instruction natively.
> +	 */
> +	asm volatile(".byte 0xf3, 0x0f, 0xae, 0xf7;"
> +			:
> +			: "D"(addr));
> +#endif
> +}
> +
> +static void intel_umwait(const uint64_t timeout)
> +{
> +	const uint32_t tsc_l = (uint32_t)timeout;
> +	const uint32_t tsc_h = (uint32_t)(timeout >> 32);
> +#if defined(RTE_TOOLCHAIN_MSVC) || defined(__WAITPKG__)
> +	_umwait(tsc_l, tsc_h);
> +#else
> +	asm volatile(".byte 0xf2, 0x0f, 0xae, 0xf7;"
> +			: /* ignore rflags */
> +			: "D"(0), /* enter C0.2 */
> +			  "a"(tsc_l), "d"(tsc_h));
> +#endif
> +}
> +
> +/**
> + * This functions uses MONITORX/MWAITX instructions and will enter C1 state.
> + * For more information about usage of these instructions, please refer to
> + * AMD64 Architecture Programmer’s Manual.
> + */
> +static void amd_monitorx(volatile void *addr)
> +{
> +#if defined(__MWAITX__)
> +	/* cast away "volatile" when using the intrinsic */
> +	_mm_monitorx((void *)(uintptr_t)addr, 0, 0);
> +#else
> +	asm volatile(".byte 0x0f, 0x01, 0xfa;"
> +			:
> +			: "a"(addr),
> +			"c"(0),  /* no extensions */
> +			"d"(0)); /* no hints */
> +#endif
> +}
> +
> +static void amd_mwaitx(const uint64_t timeout)
> +{
> +	RTE_SET_USED(timeout);
> +#if defined(__MWAITX__)
> +	_mm_mwaitx(0, 0, 0);
> +#else
> +	asm volatile(".byte 0x0f, 0x01, 0xfb;"
> +			: /* ignore rflags */
> +			: "a"(0), /* enter C1 */
> +			"c"(0)); /* no time-out */
> +#endif
> +}
> +
> +static struct {
> +	void (*mmonitor)(volatile void *addr);
> +	void (*mwait)(const uint64_t timeout);
> +} __rte_cache_aligned power_monitor_ops;
> +
>   static inline void
>   __umwait_wakeup(volatile void *addr)
>   {
> @@ -76,8 +148,6 @@ int
>   rte_power_monitor(const struct rte_power_monitor_cond *pmc,
>   		const uint64_t tsc_timestamp)
>   {
> -	const uint32_t tsc_l = (uint32_t)tsc_timestamp;
> -	const uint32_t tsc_h = (uint32_t)(tsc_timestamp >> 32);
>   	const unsigned int lcore_id = rte_lcore_id();
>   	struct power_wait_status *s;
>   	uint64_t cur_value;
> @@ -105,19 +175,8 @@ rte_power_monitor(const struct rte_power_monitor_cond *pmc,
>   	rte_spinlock_lock(&s->lock);
>   	s->monitor_addr = pmc->addr;
>   
> -	/* set address for UMONITOR */
> -#if defined(RTE_TOOLCHAIN_MSVC) || defined(__WAITPKG__)
> -	/* cast away "volatile" when using the intrinsic */
> -	_umonitor((void *)(uintptr_t)pmc->addr);
> -#else
> -	/*
> -	 * we're using raw byte codes for compiler versions which
> -	 * don't support this instruction natively.
> -	 */
> -	asm volatile(".byte 0xf3, 0x0f, 0xae, 0xf7;"
> -			:
> -			: "D"(pmc->addr));
> -#endif
> +	/* set address for memory monitor */
> +	power_monitor_ops.mmonitor(pmc->addr);
>   
>   	/* now that we've put this address into monitor, we can unlock */
>   	rte_spinlock_unlock(&s->lock);
> @@ -128,15 +187,8 @@ rte_power_monitor(const struct rte_power_monitor_cond *pmc,
>   	if (pmc->fn(cur_value, pmc->opaque) != 0)
>   		goto end;
>   
> -	/* execute UMWAIT */
> -#if defined(RTE_TOOLCHAIN_MSVC) || defined(__WAITPKG__)
> -	_umwait(tsc_l, tsc_h);
> -#else
> -	asm volatile(".byte 0xf2, 0x0f, 0xae, 0xf7;"
> -			: /* ignore rflags */
> -			: "D"(0), /* enter C0.2 */
> -			  "a"(tsc_l), "d"(tsc_h));
> -#endif
> +	/* execute mwait */
> +	power_monitor_ops.mwait(tsc_timestamp);
>   
>   end:
>   	/* erase sleep address */
> @@ -186,6 +238,14 @@ RTE_INIT(rte_power_intrinsics_init) {
>   		wait_multi_supported = 1;
>   	if (i.power_monitor)
>   		monitor_supported = 1;
> +
> +	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_MONITORX)) { /* AMD */
> +		power_monitor_ops.mmonitor = &amd_monitorx;
> +		power_monitor_ops.mwait = &amd_mwaitx;
> +	} else { /* Intel */
> +		power_monitor_ops.mmonitor = &intel_umonitor;
> +		power_monitor_ops.mwait = &intel_umwait;
> +	}
>   }
>   
>   int

Acked-by: Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>