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

[Zhang, Qi Z]

> -----Original Message-----
> From: Xing, Beilei
> Sent: Thursday, June 28, 2018 9:46 AM
> To: Zhang, Qi Z <qi.z.zhang at intel.com>
> Cc: Wu, Jingjing <jingjing.wu at intel.com>; Yu, De <de.yu at intel.com>;
> dev at dpdk.org
> Subject: RE: [PATCH v3] net/i40e: remove VF interrupt handler
> 
> 
> 
> > -----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>

Applied to dpdk-next-net-intel.

Thanks!
Qi