Re: [dpdk-users] i40e vPMD fix out of order Rx read issue

[Ye Xiaolong <xiaolong.ye@intel.com>]

On 08/14, Zhang, Qi Z wrote:
>+ Xiaolong
>
>I think we can merge them to dpdk-next-net-intel early since 19.11 cycle is started.

Ok, could you help to ack these patches?


Thanks,
Xiaolong
>
>> -----Original Message-----
>> From: Gavin Hu (Arm Technology China) [mailto:Gavin.Hu@arm.com]
>> Sent: Wednesday, August 14, 2019 11:20 AM
>> To: Zhang, Qi Z <qi.z.zhang@intel.com>; Richardson, Bruce
>> <bruce.richardson@intel.com>; Ananyev, Konstantin
>> <konstantin.ananyev@intel.com>
>> Cc: users@dpdk.org; Honnappa Nagarahalli
>> <Honnappa.Nagarahalli@arm.com>; Phil Yang (Arm Technology China)
>> <Phil.Yang@arm.com>; Ruifeng Wang (Arm Technology China)
>> <Ruifeng.Wang@arm.com>
>> Subject: RE: i40e vPMD fix out of order Rx read issue
>> 
>> Hi Qi,
>> 
>> > -----Original Message-----
>> > From: Zhang, Qi Z <qi.z.zhang@intel.com>
>> > Sent: Saturday, July 27, 2019 9:33 AM
>> > To: Gavin Hu (Arm Technology China) <Gavin.Hu@arm.com>; Richardson,
>> > Bruce <bruce.richardson@intel.com>; Ananyev, Konstantin
>> > <konstantin.ananyev@intel.com>
>> > Cc: users@dpdk.org; Honnappa Nagarahalli
>> > <Honnappa.Nagarahalli@arm.com>; Phil Yang (Arm Technology China)
>> > <Phil.Yang@arm.com>; Ruifeng Wang (Arm Technology China)
>> > <Ruifeng.Wang@arm.com>
>> > Subject: RE: i40e vPMD fix out of order Rx read issue
>> >
>> >
>> >
>> > > -----Original Message-----
>> > > From: Gavin Hu (Arm Technology China) [mailto:Gavin.Hu@arm.com]
>> > > Sent: Friday, July 26, 2019 6:01 PM
>> > > To: Zhang, Qi Z <qi.z.zhang@intel.com>; Richardson, Bruce
>> > > <bruce.richardson@intel.com>; Ananyev, Konstantin
>> > > <konstantin.ananyev@intel.com>
>> > > Cc: users@dpdk.org; Honnappa Nagarahalli
>> > > <Honnappa.Nagarahalli@arm.com>; Phil Yang (Arm Technology China)
>> > > <Phil.Yang@arm.com>; Ruifeng Wang (Arm Technology China)
>> > > <Ruifeng.Wang@arm.com>
>> > > Subject: RE: i40e vPMD fix out of order Rx read issue
>> > >
>> > > Hi Qi,
>> > >
>> > > Thanks for your explanation!
>> > > I did some testing and found the barriers caused a big drop in
>> > > RFC2544 NDR performance on aarch64, how about it on X86?
>> > For x86, I think we don't have performance drop, the memory barrier
>> > just change the compiler's behavior to avoid generate out of order
>> > read instructions, and x86 guarantee no out of read execution, so it
>> > does not add new instructions that cost CPU cycles.
>> >
>> > > Is it possible to count DD bits in a way of surviving across the
>> > > out-of-order descriptors reading?
>> >
>> > I think it is possible, but this will impact performance on x86, but
>> > for aarch64, you can try out to see if that benefit and do proper
>> > optimization on related vPMD implementation.
>> The patches for aarch64 are in community review, and performances gain
>> were measured both for ixgbe and i40e vPMD. Very appreciate if you can
>> further review and comment.
>> Here are the patch links:
>> IXGBE vPMD:
>> http://patches.dpdk.org/patch/57649/
>> http://patches.dpdk.org/patch/57650/
>> I40e vPMD:
>> http://patches.dpdk.org/cover/57651/
>> http://patches.dpdk.org/patch/57652/
>
>
>
>> > >
>> > > Best Regards,
>> > > Gavin
>> > >
>> > > > -----Original Message-----
>> > > > From: Zhang, Qi Z <qi.z.zhang@intel.com>
>> > > > Sent: Thursday, July 25, 2019 8:11 PM
>> > > > To: Gavin Hu (Arm Technology China) <Gavin.Hu@arm.com>;
>> > > > Richardson, Bruce <bruce.richardson@intel.com>; Ananyev,
>> > > > Konstantin <konstantin.ananyev@intel.com>
>> > > > Cc: users@dpdk.org; Honnappa Nagarahalli
>> > > > <Honnappa.Nagarahalli@arm.com>; Phil Yang (Arm Technology China)
>> > > > <Phil.Yang@arm.com>
>> > > > Subject: RE: i40e vPMD fix out of order Rx read issue
>> > > >
>> > > > Hi Gavin:
>> > > >
>> > > > in vPMD, we read 4 or 8 packets as batch, we count DD bits for
>> > > > packet received, but not check the if they are continues or not,
>> > > > we assume it should always be 1000, 1100, 1110, 1111 ....(take
>> > > > batch size is 4 as
>> > > > example) while the out of order read instruction generated by
>> > > > compiler will cause driver to get un-continues DD bits, like 1011,
>> > > > the descriptor on the hole actually is invalid since when it is
>> > > > read , descriptor is not write back yet, but we still process this
>> > > > as 1110, it cause
>> > an
>> > > corrupted mbuf returned.
>> > > >
>> > > > hope this is helpful.
>> > > >
>> > > > Regards
>> > > > Qi
>> > > >
>> > > > > -----Original Message-----
>> > > > > From: Gavin Hu (Arm Technology China) [mailto:Gavin.Hu@arm.com]
>> > > > > Sent: Thursday, July 25, 2019 5:57 PM
>> > > > > To: Zhang, Qi Z <qi.z.zhang@intel.com>; Richardson, Bruce
>> > > > > <bruce.richardson@intel.com>; Ananyev, Konstantin
>> > > > > <konstantin.ananyev@intel.com>
>> > > > > Cc: users@dpdk.org; Honnappa Nagarahalli
>> > > > > <Honnappa.Nagarahalli@arm.com>; Phil Yang (Arm Technology China)
>> > > > > <Phil.Yang@arm.com>
>> > > > > Subject: i40e vPMD fix out of order Rx read issue
>> > > > >
>> > > > > Hi Qi,
>> > > > >
>> > > > > I am working on optimizing the i40e vPMD on aarch64 and I see
>> > > > > this patch relevant.
>> > > > > Could you illuminate what issue this patch was fixing?
>> > > > > I understand the PMD works at the driver layer, for delivery of
>> > > > > L2
>> > packets.
>> > > > > It does not own the responsibility to keep order(the
>> > > > > responsibility lies with
>> > > > the
>> > > > > protocol stack, like TCP)?
>> > > > >
>> > > > > http://patches.dpdk.org/patch/16665/
>> > > > >
>> > > > > Best regards,
>> > > > > Gavin
>> > > > >
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>> IMPORTANT NOTICE: The contents of this email and any attachments are
>> confidential and may also be privileged. If you are not the intended recipient,
>> please notify the sender immediately and do not disclose the contents to any
>> other person, use it for any purpose, or store or copy the information in any
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