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From: "Nicolas de Pesloüan" <nicolas.2p.debian@gmail•com>
To: Simon Chen <simonchennj@gmail•com>
Cc: netdev@vger•kernel.org
Subject: Re: bonding xmit_policy
Date: Sun, 13 Nov 2011 21:26:50 +0100	[thread overview]
Message-ID: <4EC0280A.3060100@gmail.com> (raw)
In-Reply-To: <CANj2Ebfj+7R+wCK7jJennBN7_6THJGqs8FWSAPOv7BYYsR=u9w@mail.gmail.com>

Le 13/11/2011 03:55, Simon Chen a écrit :
> Hi folks,
>
> It looks like that there are three entries in xmit_policy (hashing for
> deciding egress phy int) for bonded interfaces:
>
> const struct bond_parm_tbl xmit_hashtype_tbl[] = {
> {       "layer2",               BOND_XMIT_POLICY_LAYER2},
> {       "layer3+4",             BOND_XMIT_POLICY_LAYER34},
> {       "layer2+3",             BOND_XMIT_POLICY_LAYER23},
> {       NULL,                   -1},
> };
>
>
> We can set the xmit_policy either at module initiation, or later via
> /sys. However, this xmit_policy isn't really read anywhere. Are
> different policies really implemented?

The table is used in two different locations:

In drivers/net/bonding/bond_main.c:

	xmit_hashtype = bond_parse_parm(xmit_hash_policy, xmit_hashtype_tbl);
	[...]
	params->xmit_policy = xmit_hashtype;

In drivers/net/bonding/bond_sysfs.c:

	new_value = bond_parse_parm(buf, xmit_hashtype_tbl);
	[...]
	bonds->params.xmit_policy = new_value;

Then, in drivers/net/bonding/bond_main.c, the value in bonds->params.xmit_policy is used to setup a 
callback into bond->xmit_hash_policy.

	static void bond_set_xmit_hash_policy(struct bonding *bond)
	{
	        switch (bond->params.xmit_policy) {
	        case BOND_XMIT_POLICY_LAYER23:
	                bond->xmit_hash_policy = bond_xmit_hash_policy_l23;
	                break;
	        case BOND_XMIT_POLICY_LAYER34:
	                bond->xmit_hash_policy = bond_xmit_hash_policy_l34;
	                break;
	        case BOND_XMIT_POLICY_LAYER2:
         	default:
	                bond->xmit_hash_policy = bond_xmit_hash_policy_l2;
	                break;
	        }
	}

Then, in drivers/net/bonding/bond_3ad.c and in drivers/net/bonding/bond_main.c, the callback is used 
to select a slave for xmit, for the two modes where xmit_hash_policy have a meaning:

         slave_agg_no = bond->xmit_hash_policy(skb, slaves_in_agg);

         slave_no = bond->xmit_hash_policy(skb, bond->slave_cnt);


So, yes, those policies are really implemented.

	Nicolas.

next prev parent reply	other threads:[~2011-11-13 20:26 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-11-13  2:55 bonding xmit_policy Simon Chen
2011-11-13 20:26 ` Nicolas de Pesloüan [this message]
2011-11-15  6:20   ` Simon Chen
2011-11-15  7:12     ` Eric Dumazet

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