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Message-ID: <20130926054317.GA2547@redhat.com>
Date: Thu, 26 Sep 2013 07:43:17 +0200
From: Veaceslav Falico <vfalico@...hat.com>
To: Ding Tianhong <dingtianhong@...wei.com>
Cc: netdev@...r.kernel.org, jiri@...nulli.us,
Jay Vosburgh <fubar@...ibm.com>,
Andy Gospodarek <andy@...yhouse.net>
Subject: Re: [PATCH v5 net-next 11/27] bonding: rework bond_3ad_xmit_xor() to
use bond_for_each_slave() only
On Thu, Sep 26, 2013 at 10:31:35AM +0800, Ding Tianhong wrote:
First of all - thanks a lot for the review! Answered below.
>On 2013/9/25 15:20, Veaceslav Falico wrote:
>> Currently, there are two loops - first we find the first slave in an
>> aggregator after the xmit_hash_policy() returned number, and after that we
>> loop from that slave, over bonding head, and till that slave to find any
>> suitable slave to send the packet through.
>>
>> Replace it by just one bond_for_each_slave() loop, which first loops
>> through the requested number of slaves, saving the first suitable one, and
>> after that we've hit the requested number of slaves to skip - search for
>> any up slave to send the packet through. If we don't find such kind of
>> slave - then just send the packet through the first suitable slave found.
>>
>> Logic remains unchainged, and we skip two loops. Also, refactor it a bit
>> for readability.
>>
>> CC: Jay Vosburgh <fubar@...ibm.com>
>> CC: Andy Gospodarek <andy@...yhouse.net>
>> Signed-off-by: Veaceslav Falico <vfalico@...hat.com>
>> ---
>>
>> Notes:
>> v4 -> v5
>> No change.
>>
>> v3 -> v4:
>> No change.
>>
>> v2 -> v3:
>> No change.
>>
>> v1 -> v2:
>> No changes.
>>
>> RFC -> v1:
>> New patch.
>>
>> drivers/net/bonding/bond_3ad.c | 46 ++++++++++++++++++++----------------------
>> 1 file changed, 22 insertions(+), 24 deletions(-)
>>
>> diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
>> index 3847aee..c861ee7 100644
>> --- a/drivers/net/bonding/bond_3ad.c
>> +++ b/drivers/net/bonding/bond_3ad.c
>> @@ -2417,15 +2417,15 @@ int bond_3ad_get_active_agg_info(struct bonding *bond, struct ad_info *ad_info)
>>
>> int bond_3ad_xmit_xor(struct sk_buff *skb, struct net_device *dev)
>> {
>> - struct slave *slave, *start_at;
>> struct bonding *bond = netdev_priv(dev);
>> + struct slave *slave, *first_ok_slave;
>> + struct aggregator *agg;
>> + struct ad_info ad_info;
>> struct list_head *iter;
>> - int slave_agg_no;
>> int slaves_in_agg;
>> - int agg_id;
>> - int i;
>> - struct ad_info ad_info;
>> + int slave_agg_no;
>> int res = 1;
>> + int agg_id;
>>
>> read_lock(&bond->lock);
>> if (__bond_3ad_get_active_agg_info(bond, &ad_info)) {
>> @@ -2438,20 +2438,28 @@ int bond_3ad_xmit_xor(struct sk_buff *skb, struct net_device *dev)
>> agg_id = ad_info.aggregator_id;
>>
>> if (slaves_in_agg == 0) {
>> - /*the aggregator is empty*/
>> pr_debug("%s: Error: active aggregator is empty\n", dev->name);
>> goto out;
>> }
>>
>> slave_agg_no = bond->xmit_hash_policy(skb, slaves_in_agg);
>> + first_ok_slave = NULL;
>>
>> bond_for_each_slave(bond, slave, iter) {
>> - struct aggregator *agg = SLAVE_AD_INFO(slave).port.aggregator;
>> + agg = SLAVE_AD_INFO(slave).port.aggregator;
>> + if (!agg || agg->aggregator_identifier != agg_id)
>> + continue;
>>
>> - if (agg && (agg->aggregator_identifier == agg_id)) {
>> + if (slave_agg_no >= 0) {
>> + if (!first_ok_slave && SLAVE_IS_OK(slave))
>> + first_ok_slave = slave;
>> slave_agg_no--;
>> - if (slave_agg_no < 0)
>> - break;
>> + continue;
>> + }
[1] ^^^^^^^^^^^^^^^^^^^^^^^^^
>> +
>> + if (SLAVE_IS_OK(slave)) {
>> + res = bond_dev_queue_xmit(bond, skb, slave->dev);
>> + goto out;
>> }
[2] ^^^^^^^^^^^^^^^^^^^^^^^^^
>
>I think you miss something, you will send skb always by the first suitable port,
>it could not support load balance.
Well, yes, it will send always by the first suitable port AFTER
slave_agg_no, returned by the xmit_hash_policy(), which is the whole point
in the hash function and in the load balance.
It will first loop through the slaves, decrementing slave_agg_no to a
negative value, while saving the first good to send slave, as shown in [1].
Notice the "continue;":
if (slave_agg_no >= 0) {
if (!first_ok_slave && SLAVE_IS_OK(slave))
first_ok_slave = slave;
slave_agg_no--;
continue;
}
Once we hit the negative value - which means we've skipped enough slaves,
as requested by the hash function - we can start looking for the first
slave that is good to send AFTER those all skipped slaves, as shown in [2].
Down the patch we also use that 'first_ok_slave' - in case we didn't find
any suitable one after we've skipped first slave_agg_no and till the last
slave, so it implements the same 'circular' logic as was in
bond_for_each_slave_from().
>pls consult my function.
> if (agg && (agg->aggregator_identifier == agg_id)) {
>- slave_agg_no--;
>- if (slave_agg_no < 0)
>- break;
>+ if (--slave_agg_no < 0) {
>+ if (SLAVE_IS_OK(slave)) {
>+ res = bond_dev_queue_xmit(bond,
>+ skb, slave->dev);
>+ goto out;
>+ }
>+ }
I'll review your function in your patch.
> }
> }
>
>> }
>>
>> @@ -2461,20 +2469,10 @@ int bond_3ad_xmit_xor(struct sk_buff *skb, struct net_device *dev)
>> goto out;
>> }
>>
>> - start_at = slave;
>> -
>> - bond_for_each_slave_from(bond, slave, i, start_at) {
>> - int slave_agg_id = 0;
>> - struct aggregator *agg = SLAVE_AD_INFO(slave).port.aggregator;
>> -
>> - if (agg)
>> - slave_agg_id = agg->aggregator_identifier;
>> -
>> - if (SLAVE_IS_OK(slave) && agg && (slave_agg_id == agg_id)) {
>> - res = bond_dev_queue_xmit(bond, skb, slave->dev);
>> - break;
>> - }
>> - }
>> + /* we couldn't find any suitable slave after the agg_no, so use the
>> + * first suitable found, if found. */
>> + if (first_ok_slave)
>> + res = bond_dev_queue_xmit(bond, skb, first_ok_slave->dev);
>>
>> out:
>> read_unlock(&bond->lock);
>>
>
>
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