[dpdk-dev] [PATCH v3] net/i40e: remove VF interrupt handler

Xing, Beilei beilei.xing at intel.com
Thu Jun 28 03:46:22 CEST 2018



> -----Original Message-----
> From: Zhang, Qi Z
> Sent: Wednesday, June 27, 2018 9:15 PM
> To: Xing, Beilei <beilei.xing at intel.com>
> Cc: Wu, Jingjing <jingjing.wu at intel.com>; Yu, De <de.yu at intel.com>;
> dev at dpdk.org; Zhang, Qi Z <qi.z.zhang at intel.com>
> Subject: [PATCH v3] 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 at intel.com>
> Signed-off-by: Qi Zhang <qi.z.zhang at intel.com>

Acked-by: Beilei Xing <beilei.xing at intel.com>


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