From: "Zhang, Qi Z" <qi.z.zhang@intel.com>
To: "Xing, Beilei" <beilei.xing@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 13:16:18 +0000 [thread overview]
Message-ID: <039ED4275CED7440929022BC67E7061153233855@SHSMSX103.ccr.corp.intel.com> (raw)
In-Reply-To: <94479800C636CB44BD422CB454846E01321C67FF@SHSMSX101.ccr.corp.intel.com>
> -----Original Message-----
> From: Xing, Beilei
> Sent: Thursday, June 7, 2018 3:14 PM
> 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
> Subject: RE: [PATCH] net/i40e: remove VF interrupt handler
>
>
>
> > -----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.
Good capture, will fix this in v2
Thanks
Qi
>
> Beilei
next prev parent reply other threads:[~2018-06-07 13:16 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
2018-06-07 13:16 ` Zhang, Qi Z [this message]
2018-06-27 3:48 ` Xing, Beilei
2018-06-27 3:59 ` Zhang, Qi Z
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