[dpdk-dev] [RFC 2/2] drivers/net: use sleep delay by default for intel NICs

Wiles, Keith keith.wiles at intel.com
Mon Sep 3 17:14:20 CEST 2018



> On Aug 31, 2018, at 1:45 PM, Ilya Maximets <i.maximets at samsung.com> wrote:
> 
> NICs uses different delays up to a second during their
> configuration. It makes no sense to busy-wait so long wasting
> CPU cycles and preventing any other threads to execute on the
> same CPU core. These busy polling are the rudiments that came
> from the kernel drivers where you can not sleep in interrupt
> context, but as we're in userspace, we're able and should
> sleep to allow other threads to run.
> Delays never called on rx/tx path, so this should not affect
> performance.

I have a question, the only thread being effected by the busy wait is the thread assigned to the core or the master lcore in the case of rte_eal_init(). It should not effect other threads running on other cores, right? If you do have other threads running in the same code then I see the need, please help me understand the use and how it is effecting DPDK.
> 
> Signed-off-by: Ilya Maximets <i.maximets at samsung.com>
> ---
> drivers/net/avf/Makefile             | 1 +
> drivers/net/avf/base/avf_osdep.h     | 4 ++--
> drivers/net/e1000/Makefile           | 1 +
> drivers/net/e1000/base/e1000_osdep.h | 2 +-
> drivers/net/i40e/base/i40e_osdep.h   | 6 +++---
> drivers/net/ifc/base/ifcvf_osdep.h   | 2 +-
> drivers/net/ixgbe/base/ixgbe_osdep.h | 2 +-
> 7 files changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/avf/Makefile b/drivers/net/avf/Makefile
> index 3f815bbc4..8ee707529 100644
> --- a/drivers/net/avf/Makefile
> +++ b/drivers/net/avf/Makefile
> @@ -9,6 +9,7 @@ include $(RTE_SDK)/mk/rte.vars.mk
> LIB = librte_pmd_avf.a
> 
> CFLAGS += -O3
> +CFLAGS += -DALLOW_EXPERIMENTAL_API
> LDLIBS += -lrte_eal -lrte_mbuf -lrte_mempool -lrte_ring
> LDLIBS += -lrte_ethdev -lrte_net -lrte_kvargs -lrte_hash
> LDLIBS += -lrte_bus_pci
> diff --git a/drivers/net/avf/base/avf_osdep.h b/drivers/net/avf/base/avf_osdep.h
> index 9ef45968e..442a5acd0 100644
> --- a/drivers/net/avf/base/avf_osdep.h
> +++ b/drivers/net/avf/base/avf_osdep.h
> @@ -93,8 +93,8 @@ typedef uint64_t        u64;
> #define avf_memset(a, b, c, d) memset((a), (b), (c))
> #define avf_memcpy(a, b, c, d) rte_memcpy((a), (b), (c))
> 
> -#define avf_usec_delay(x) rte_delay_us(x)
> -#define avf_msec_delay(x) rte_delay_us(1000*(x))
> +#define avf_usec_delay(x) rte_delay_us_sleep(x)
> +#define avf_msec_delay(x) avf_usec_delay(1000 * (x))
> 
> #define AVF_PCI_REG(reg)		rte_read32(reg)
> #define AVF_PCI_REG_ADDR(a, reg) \
> diff --git a/drivers/net/e1000/Makefile b/drivers/net/e1000/Makefile
> index 9c87e883b..0ed627656 100644
> --- a/drivers/net/e1000/Makefile
> +++ b/drivers/net/e1000/Makefile
> @@ -10,6 +10,7 @@ LIB = librte_pmd_e1000.a
> 
> CFLAGS += -O3
> CFLAGS += $(WERROR_FLAGS)
> +CFLAGS += -DALLOW_EXPERIMENTAL_API
> LDLIBS += -lrte_eal -lrte_mbuf -lrte_mempool -lrte_ring
> LDLIBS += -lrte_ethdev -lrte_net -lrte_kvargs
> LDLIBS += -lrte_bus_pci
> diff --git a/drivers/net/e1000/base/e1000_osdep.h b/drivers/net/e1000/base/e1000_osdep.h
> index b8868049f..5958ea157 100644
> --- a/drivers/net/e1000/base/e1000_osdep.h
> +++ b/drivers/net/e1000/base/e1000_osdep.h
> @@ -48,7 +48,7 @@
> 
> #include "../e1000_logs.h"
> 
> -#define DELAY(x) rte_delay_us(x)
> +#define DELAY(x) rte_delay_us_sleep(x)
> #define usec_delay(x) DELAY(x)
> #define usec_delay_irq(x) DELAY(x)
> #define msec_delay(x) DELAY(1000*(x))
> diff --git a/drivers/net/i40e/base/i40e_osdep.h b/drivers/net/i40e/base/i40e_osdep.h
> index 8e5c593c9..a6072e153 100644
> --- a/drivers/net/i40e/base/i40e_osdep.h
> +++ b/drivers/net/i40e/base/i40e_osdep.h
> @@ -233,9 +233,9 @@ struct i40e_spinlock {
> #define i40e_memcpy(a, b, c, d) rte_memcpy((a), (b), (c))
> 
> #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
> -#define DELAY(x) rte_delay_us(x)
> -#define i40e_usec_delay(x) rte_delay_us(x)
> -#define i40e_msec_delay(x) rte_delay_us(1000*(x))
> +#define DELAY(x) rte_delay_us_sleep(x)
> +#define i40e_usec_delay(x) DELAY(x)
> +#define i40e_msec_delay(x) DELAY(1000 * (x))
> #define udelay(x) DELAY(x)
> #define msleep(x) DELAY(1000*(x))
> #define usleep_range(min, max) msleep(DIV_ROUND_UP(min, 1000))
> diff --git a/drivers/net/ifc/base/ifcvf_osdep.h b/drivers/net/ifc/base/ifcvf_osdep.h
> index cf151ef52..6aef25ea4 100644
> --- a/drivers/net/ifc/base/ifcvf_osdep.h
> +++ b/drivers/net/ifc/base/ifcvf_osdep.h
> @@ -17,7 +17,7 @@
> #define DEBUGOUT(S, args...)    RTE_LOG(DEBUG, PMD, S, ##args)
> #define STATIC                  static
> 
> -#define msec_delay	rte_delay_ms
> +#define msec_delay(x)	rte_delay_us_sleep(1000 * (x))
> 
> #define IFCVF_READ_REG8(reg)		rte_read8(reg)
> #define IFCVF_WRITE_REG8(val, reg)	rte_write8((val), (reg))
> diff --git a/drivers/net/ixgbe/base/ixgbe_osdep.h b/drivers/net/ixgbe/base/ixgbe_osdep.h
> index bb5dfd2af..94ede9bc2 100644
> --- a/drivers/net/ixgbe/base/ixgbe_osdep.h
> +++ b/drivers/net/ixgbe/base/ixgbe_osdep.h
> @@ -51,7 +51,7 @@
> 
> #define ASSERT(x) if(!(x)) rte_panic("IXGBE: x")
> 
> -#define DELAY(x) rte_delay_us(x)
> +#define DELAY(x) rte_delay_us_sleep(x)
> #define usec_delay(x) DELAY(x)
> #define msec_delay(x) DELAY(1000*(x))
> 
> -- 
> 2.17.1
> 

Regards,
Keith



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