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Message-ID: <20130306200140.GB19544@gospo.rdu.redhat.com>
Date: Wed, 6 Mar 2013 15:01:40 -0500
From: Andy Gospodarek <andy@...yhouse.net>
To: Jay Vosburgh <fubar@...ibm.com>
Cc: netdev@...r.kernel.org
Subject: Re: [PATCH net-next] bond: add support to read speed and duplex via
ethtool
On Wed, Mar 06, 2013 at 11:25:12AM -0800, Jay Vosburgh wrote:
> Andy Gospodarek <andy@...yhouse.net> wrote:
>
> >This patch adds support for the get_settings ethtool op to the bonding
> >driver. This was motivated by users who wanted to get the speed of the
> >bond and compare that against throughput to understand utilization.
> >The behavior before this patch was added was problematic when computing
> >line utilization after trying to get link-speed and throughput via SNMP.
> >
> >The general plan for computing link-speed was as follows:
> >
> >Mode Formula
> >---- -------
> >active-backup speed of current active slave
> >broadcast speed of first slave with known speed
> >all other modes aggregate speed of all slaves with known speed
>
> I'll just point out that the balance-tlb mode is asymmetric; it
> uses all slaves for transmission, but only one slave for reception.
> Ethtool only has a single speed for both directions, so this is probably
> the best choice, but it should still be noted.
Thanks for pointing that out. I have a feeling there will be a v2, so
I'll try and update the changelog to reflect that. For the record, this
same limitation exists when connecting to most switches and using
round-robin, so I didn't feel the need to differentiate possibly
asymmetric speeds.
> >Output from ethtool looks like this for a round-robin bond:
> >
> >Settings for bond0:
> > Supported ports: [ ]
> > Supported link modes: Not reported
> > Supported pause frame use: No
> > Supports auto-negotiation: No
> > Advertised link modes: Not reported
> > Advertised pause frame use: No
> > Advertised auto-negotiation: No
> > Speed: 11000Mb/s
> > Duplex: Full
> > Port: Twisted Pair
> > PHYAD: 0
> > Transceiver: internal
> > Auto-negotiation: off
> > MDI-X: Unknown
> > Link detected: yes
> >
> >I tested this and verified it works as expected. A test was also done
> >on a version backported to an older kernel and it worked well there.
> >
> >Signed-off-by: Andy Gospodarek <andy@...yhouse.net>
> >---
> > drivers/net/bonding/bond_main.c | 47 +++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 47 insertions(+)
> >
> >diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> >index 7bd068a..6e70ff0 100644
> >--- a/drivers/net/bonding/bond_main.c
> >+++ b/drivers/net/bonding/bond_main.c
> >@@ -4224,6 +4224,52 @@ void bond_set_mode_ops(struct bonding *bond, int mode)
> > }
> > }
> >
> >+static int bond_ethtool_get_settings(struct net_device *bond_dev,
> >+ struct ethtool_cmd *ecmd)
> >+{
> >+ struct bonding *bond = netdev_priv(bond_dev);
> >+ struct slave *slave;
> >+ int i;
> >+ unsigned long speed = 0;
> >+
> >+ ecmd->speed = SPEED_UNKNOWN;
> >+ ecmd->duplex = DUPLEX_UNKNOWN;
> >+
> >+ read_lock(&bond->lock);
> >+ switch (bond->params.mode) {
> >+ case BOND_MODE_ACTIVEBACKUP:
> >+ read_lock(&bond->curr_slave_lock);
> >+ if (bond->curr_active_slave &&
> >+ bond->curr_active_slave->speed != SPEED_UNKNOWN) {
> >+ ecmd->speed = bond->curr_active_slave->speed;
> >+ ecmd->duplex = bond->curr_active_slave->duplex;
> >+ }
> >+ read_unlock(&bond->curr_slave_lock);
> >+ break;
> >+ case BOND_MODE_BROADCAST:
> >+ bond_for_each_slave(bond, slave, i) {
> >+ if (slave->speed != SPEED_UNKNOWN) {
> >+ ecmd->speed = slave->speed;
> >+ ecmd->duplex = slave->duplex;
> >+ break;
> >+ }
> >+ }
> >+ break;
>
> Does anybody really use broadcast mode? Not that I'm saying
> this is incorrect, I'm just wondering in general.
>
I don't imagine they do, but wanted to add something for it since it
would not reallyu fall into the default case well.
> >+ default:
> >+ bond_for_each_slave(bond, slave, i) {
> >+ if (slave->speed != SPEED_UNKNOWN) {
> >+ speed += slave->speed;
> >+ }
> >+ if (ecmd->duplex == DUPLEX_UNKNOWN &&
> >+ slave->duplex != DUPLEX_UNKNOWN)
> >+ ecmd->duplex = slave->duplex;
>
> Should the calculations skip slaves that are not BOND_LINK_UP?
> If the ARP monitor is running, some slaves may be carrier up (and have
> slave->speed set), but are not actually in use by the bond, at least for
> transmission.
>
That would be fine with me. If you would like I can add that for a v2.
It would produce a more honest estimate of what the maximum throughput
would be at that point in time.
> -J
>
> >+ }
> >+ ecmd->speed = speed;
> >+ }
> >+ read_unlock(&bond->lock);
> >+ return 0;
> >+}
> >+
> > static void bond_ethtool_get_drvinfo(struct net_device *bond_dev,
> > struct ethtool_drvinfo *drvinfo)
> > {
> >@@ -4235,6 +4281,7 @@ static void bond_ethtool_get_drvinfo(struct net_device *bond_dev,
> >
> > static const struct ethtool_ops bond_ethtool_ops = {
> > .get_drvinfo = bond_ethtool_get_drvinfo,
> >+ .get_settings = bond_ethtool_get_settings,
> > .get_link = ethtool_op_get_link,
> > };
> >
> >--
> >1.7.11.7
>
> ---
> -Jay Vosburgh, IBM Linux Technology Center, fubar@...ibm.com
>
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