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Date: Wed, 17 Aug 2016 17:51:11 +0800
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: Maxime Coquelin <maxime.coquelin@redhat.com>
Cc: "Wang, Zhihong" <zhihong.wang@intel.com>, "dev@dpdk.org" <dev@dpdk.org>
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Subject: Re: [dpdk-dev] [PATCH] optimize vhost enqueue
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On Wed, Aug 17, 2016 at 11:17:46AM +0200, Maxime Coquelin wrote:
> >>>This is something I've thought about while writing the code, the reason I
> >>>keep it as one function body is that:
> >>>
> >>> 1. This function is very performance sensitive, and we need full control of
> >>>    code ordering (You can compare with the current performance with the
> >>>    mrg_rxbuf feature turned on to see the difference).
> >>
> >>Will inline functions help?
> >
> >
> >Optimization in this patch actually reorganizes the code from its logic,
> >so it's not suitable for making separated functions.
> >
> >I'll explain this in v2.
> 
> I agree with Yuanhan.
> Inline functions should not break the optimizations.
> IMHO, this is mandatory for the patch to be accepted.

Yes.

> It seems you are not the only one facing the issue:
> https://github.com/YanVugenfirer/kvm-guest-drivers-windows/issues/70
> 
> So a dedicated fix is really important.

Yes.

> 
> >This patch doesn't try to fix this issue, it rewrites the logic totally,
> >and somehow fixes this issue.
> >
> >Do you think integrating this whole patch into the stable branch will work?
> >Personally I think it makes more sense.
> 
> No.
> We don't even know why/how it fixes the Windows issue, which would be
> the first thing to understand before integrating a fix in stable branch.

Yes.

> 
> And the stable branch is not meant for integrating such big reworks,
> it is only meant to fix bugs.

Yes.

> The risk of regressions have to be avoided as much as possible.

Yes.

	--yliu