From: "Xing, Beilei" <beilei.xing@intel.com>
To: "Zhang, Qi Z" <qi.z.zhang@intel.com>
Cc: "Wu, Jingjing" <jingjing.wu@intel.com>,
"Yu, De" <de.yu@intel.com>, "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] net/i40e: remove VF interrupt handler
Date: Thu, 7 Jun 2018 07:14:05 +0000 [thread overview]
Message-ID: <94479800C636CB44BD422CB454846E01321C67FF@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: <20180607013156.28763-1-qi.z.zhang@intel.com>
> -----Original Message-----
> From: Zhang, Qi Z
> Sent: Thursday, June 7, 2018 9:32 AM
> To: Xing, Beilei <beilei.xing@intel.com>
> Cc: Wu, Jingjing <jingjing.wu@intel.com>; Yu, De <de.yu@intel.com>;
> dev@dpdk.org; Zhang, Qi Z <qi.z.zhang@intel.com>
> Subject: [PATCH] net/i40e: remove VF interrupt handler
>
> For i40evf, internal rx interrupt and adminq interrupt share the same source,
> that cause a lot cpu cycles be wasted on interrupt handler on rx path. This is
> complained by customers which require low latency (when set
> I40E_ITR_INTERVAL to small value), but have to be sufferred by tremendous
> interrupts handling that eat significant CPU resources.
>
> The patch disable pci interrupt and remove the interrupt handler, replace it
> with a low frequency (50ms) interrupt polling daemon which is implemented
> by registering a alarm callback periodly, this save CPU time significently: On a
> typical x86 server with 2.1GHz CPU, with low latency configure (32us) we saw
> CPU usage from top commmand reduced from 20% to 0% on management
> core in testpmd).
>
> Also with the new method we can remove compile option:
> I40E_ITR_INTERVAL which is used to balance between low latency and low
> CPU usage previously.
> Now we don't need it since we can reach both at same time.
>
> Suggested-by: Jingjing Wu <jingjing.wu@intel.com>
> Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
> ---
> config/common_base | 2 --
> drivers/net/i40e/i40e_ethdev.c | 3 +--
> drivers/net/i40e/i40e_ethdev.h | 22 +++++++++++-----------
> drivers/net/i40e/i40e_ethdev_vf.c | 36 ++++++++++++++----------------------
> 4 files changed, 26 insertions(+), 37 deletions(-)
>
> diff --git a/config/common_base b/config/common_base index
> 6b0d1cbbb..9e21c6865 100644
> --- a/config/common_base
> +++ b/config/common_base
> @@ -264,8 +264,6 @@ CONFIG_RTE_LIBRTE_I40E_INC_VECTOR=y
> CONFIG_RTE_LIBRTE_I40E_16BYTE_RX_DESC=n
> CONFIG_RTE_LIBRTE_I40E_QUEUE_NUM_PER_PF=64
> CONFIG_RTE_LIBRTE_I40E_QUEUE_NUM_PER_VM=4
> -# interval up to 8160 us, aligned to 2 (or default value)
> -CONFIG_RTE_LIBRTE_I40E_ITR_INTERVAL=-1
Then description about CONFIG_RTE_LIBRTE_I40E_ITR_INTERVAL in documentation should also be removed.
Beilei
next prev parent reply other threads:[~2018-06-07 7:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-07 1:31 Qi Zhang
2018-06-07 7:14 ` Xing, Beilei [this message]
2018-06-07 13:16 ` Zhang, Qi Z
2018-06-27 3:48 ` Xing, Beilei
2018-06-27 3:59 ` Zhang, Qi Z
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