Re: [dpdk-stable] [dpdk-dev] [PATCH] net/iavf: fix frequent command interaction leads to high cpu

["Zhang, Qi Z" <qi.z.zhang@intel.com>]

> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Qiming Chen
> Sent: Saturday, September 11, 2021 12:02 PM
> To: dev@dpdk.org
> Cc: Xing, Beilei <beilei.xing@intel.com>; Wu, Jingjing <jingjing.wu@intel.com>;
> Qiming Chen <chenqiming_huawei@163.com>; stable@dpdk.org
> Subject: [dpdk-dev] [PATCH] net/iavf: fix frequent command interaction leads
> to high cpu
> 
> There is currently a scenario test, which will continuously obtain port statistics,
> causing the CPU usage to soar, which does not meet the demand. After
> positioning analysis, it is found that the vf and pf command interaction is
> completed through the iavf_execute_vf_cmd function.
> After the message is sent, it needs to wait for the interrupt thread to obtain
> the response from the PF. For the data, the rte_delay_ms interface is used here
> to wait, but the CPU will not be released during the waiting period of this
> interface, which will cause the statistics to keep occupying the CPU. This is also
> the root cause of the soaring cpu.
> The command interaction should belong to the control plane, and there will
> not be too high requirements for performance. It is recommended to wait for
> the interface iavf_msec_delay to complete without taking up the CPU time.
> 
> Fixes: 22b123a36d07 ("net/avf: initialize PMD")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Qiming Chen <chenqiming_huawei@163.com>

Acked-by: Qi Zhang <qi.z.zhang@intel.com>

Applied to dpdk-next-net-intel.

Thanks
Qi
> ---
>  drivers/net/iavf/iavf_vchnl.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/iavf/iavf_vchnl.c b/drivers/net/iavf/iavf_vchnl.c index
> 06dc663947..2f39c2077c 100644
> --- a/drivers/net/iavf/iavf_vchnl.c
> +++ b/drivers/net/iavf/iavf_vchnl.c
> @@ -181,7 +181,7 @@ iavf_execute_vf_cmd(struct iavf_adapter *adapter,
> struct iavf_cmd_info *args)
>  						   args->out_buffer);
>  			if (result == IAVF_MSG_CMD)
>  				break;
> -			rte_delay_ms(ASQ_DELAY_MS);
> +			iavf_msec_delay(ASQ_DELAY_MS);
>  		} while (i++ < MAX_TRY_TIMES);
>  		if (i >= MAX_TRY_TIMES ||
>  		    vf->cmd_retval != VIRTCHNL_STATUS_SUCCESS) { @@ -207,7
> +207,7 @@ iavf_execute_vf_cmd(struct iavf_adapter *adapter, struct
> iavf_cmd_info *args)
>  				err = -1;
>  				break;
>  			}
> -			rte_delay_ms(ASQ_DELAY_MS);
> +			iavf_msec_delay(ASQ_DELAY_MS);
>  			/* If don't read msg or read sys event, continue */
>  		} while (i++ < MAX_TRY_TIMES);
>  		if (i >= MAX_TRY_TIMES ||
> @@ -225,7 +225,7 @@ iavf_execute_vf_cmd(struct iavf_adapter *adapter,
> struct iavf_cmd_info *args)
>  		do {
>  			if (vf->pend_cmd == VIRTCHNL_OP_UNKNOWN)
>  				break;
> -			rte_delay_ms(ASQ_DELAY_MS);
> +			iavf_msec_delay(ASQ_DELAY_MS);
>  			/* If don't read msg or read sys event, continue */
>  		} while (i++ < MAX_TRY_TIMES);
> 
> --
> 2.30.1.windows.1