netdev - Re: [PATCH net-next 2/2] bonding: use l4 hash if available

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Message-ID: <1442366082.4116.26.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Tue, 15 Sep 2015 18:14:42 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Mahesh Bandewar <maheshb@...gle.com>
Cc:	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	Tom Herbert <tom@...bertland.com>
Subject: Re: [PATCH net-next 2/2] bonding: use l4 hash if available

On Tue, 2015-09-15 at 17:04 -0700, Mahesh Bandewar wrote:
> On Tue, Sep 15, 2015 at 4:20 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> > On Tue, 2015-09-15 at 15:54 -0700, Mahesh Bandewar wrote:
> >
> >> > +       if (bond->params.xmit_policy == BOND_XMIT_POLICY_ENCAP34 &&
> >> > +           skb->l4_hash)
> >> if (ENCAP34 || LAYER34) && l4_hash) may be?
> >
> > Hmm, traditional BOND_XMIT_POLICY_LAYER34 did not a full flow bisection
> > (tunnel awareness added in commit
> > 32819dc1834866cb9547cb75f81af9edd58d33cd bonding: modify the old and add
> > new xmit hash policies)
> >
> > This could radically change some setups and behavior.
> >
> > BOND_XMIT_POLICY_ENCAP34 looks a better fit to me.
> >
> Agreed, this will change flow distribution for LAYER34 policy but then
> loose out on calculating hash per packet which I think is unnecessary.

We added new bonding policy exactly for this.

If people are stuck with LAYER34, that is their choice.

> 
> This elimination of hash calculation is a good step but I'm feeling
> that it's somehow tied to ENCAP policy which is actually orthogonal
> and should be applied to LAYER34 also.

You can send a followup patch, once fully tested.

I've tested the ENCAP34 mode only, I do not want to add cycles for a
mode that is potentially a legacy one that nobody uses.



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