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Message-ID: <4C0ED931.6030402@canonical.com>
Date: Tue, 08 Jun 2010 17:58:41 -0600
From: Tim Gardner <tim.gardner@...onical.com>
To: Tom Herbert <therbert@...gle.com>
CC: Eric Dumazet <eric.dumazet@...il.com>,
John Fastabend <john.r.fastabend@...el.com>,
Stephen Hemminger <shemminger@...tta.com>,
Peter Lieven <pl@....net>,
"davem@...emloft.net" <davem@...emloft.net>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: RFS seems to have incompatiblities with bridged vlans
On 06/08/2010 05:00 PM, Tom Herbert wrote:
> How about only checking against dev->num_rx_queues when that value is
> greater than one. Since bonding device is calling alloc_netdev, it is
> not going to set the queue mapping, but dev->num_rx_queues will be one
> in that case (this handles any intermediate driver that does do
> multiple queues).
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 6f330ce..30ab66d 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -2270,7 +2270,7 @@ static int get_rps_cpu(struct net_device *dev,
> struct sk_buff *skb,
> u16 v16[2];
> } ports;
>
> - if (skb_rx_queue_recorded(skb)) {
> + if (skb_rx_queue_recorded(skb)&& dev->num_rx_queues> 1) {
> u16 index = skb_get_rx_queue(skb);
> if (unlikely(index>= dev->num_rx_queues)) {
> if (net_ratelimit()) {
>
>
> On Tue, Jun 8, 2010 at 7:18 AM, Eric Dumazet<eric.dumazet@...il.com> wrote:
>> Le lundi 07 juin 2010 à 15:30 -0700, John Fastabend a écrit :
>>
>>> There is always a possibility that the underlying device sets the
>>> queue_mapping to be greater then num_cpus. Also I suspect the same
>>> issue exists with bonding devices. Maybe something like the following
>>> is worth while? compile tested only,
>>>
>>> [PATCH] 8021q: vlan reassigns dev without check queue_mapping
>>>
>>> recv path reassigns skb->dev without sanity checking the
>>> queue_mapping field. This can result in the queue_mapping
>>> field being set incorrectly if the new dev supports less
>>> queues then the underlying device.
>>>
>>> This patch just resets the queue_mapping to 0 which should
>>> resolve this issue? Any thoughts?
>>>
>>> The same issue could happen on bonding devices as well.
>>>
>>> Signed-off-by: John Fastabend<john.r.fastabend@...el.com>
>>> ---
>>>
>>> net/8021q/vlan_core.c | 6 ++++++
>>> 1 files changed, 6 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
>>> index bd537fc..ad309f8 100644
>>> --- a/net/8021q/vlan_core.c
>>> +++ b/net/8021q/vlan_core.c
>>> @@ -21,6 +21,9 @@ int __vlan_hwaccel_rx(struct sk_buff *skb, struct
>>> vlan_group *grp,
>>> if (!skb->dev)
>>> goto drop;
>>>
>>> + if (unlikely(skb->queue_mapping>= skb->dev->real_num_tx_queues))
>>> + skb_set_queue_mapping(skb, 0);
>>> +
>>> return (polling ? netif_receive_skb(skb) : netif_rx(skb));
>>>
>>> drop:
>>> @@ -93,6 +96,9 @@ vlan_gro_common(struct napi_struct *napi, struct
>>> vlan_group *grp,
>>> if (!skb->dev)
>>> goto drop;
>>>
>>> + if (unlikely(skb->queue_mapping>= skb->dev->real_num_tx_queues))
>>> + skb_set_queue_mapping(skb, 0);
>>> +
>>> for (p = napi->gro_list; p; p = p->next) {
>>> NAPI_GRO_CB(p)->same_flow =
>>> p->dev == skb->dev&& !compare_ether_header(
>>> --
>>
>> Only a workaround, added in hot path in a otherwise 'good' driver
>> (multiqueue enabled and ready)
>>
>> eth0 -------> bond / bridge ---------> vlan.id
>> (nbtxq=8) (ntxbq=1) (nbtxq=X)
>>
>> X is capped to 1 because of bond/bridge, while bond has no "queue"
>> (LLTX driver)
>>
>> Solutions :
>>
>> 1) queue_mapping could be silently tested in get_rps_cpu()...
>>
>> diff --git a/net/core/dev.c b/net/core/dev.c
>> index 6f330ce..3a3f7f6 100644
>> --- a/net/core/dev.c
>> +++ b/net/core/dev.c
>> @@ -2272,14 +2272,11 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
>>
>> if (skb_rx_queue_recorded(skb)) {
>> u16 index = skb_get_rx_queue(skb);
>> - if (unlikely(index>= dev->num_rx_queues)) {
>> - if (net_ratelimit()) {
>> - pr_warning("%s received packet on queue "
>> - "%u, but number of RX queues is %u\n",
>> - dev->name, index, dev->num_rx_queues);
>> - }
>> - goto done;
>> - }
>> + if (WARN_ONCE(index>= dev->num_rx_queues,
>> + KERN_WARNING "%s received packet on queue %u, "
>> + "but number of RX queues is %u\n",
>> + dev->name, index, dev->num_rx_queues))
>> + index %= dev->num_rx_queues;
>> rxqueue = dev->_rx + index;
>> } else
>> rxqueue = dev->_rx;
>>
>>
>>
>> 2) bond/bridge should setup more queues, just in case.
>> We probably need to be able to make things more dynamic,
>> (propagate nbtxq between layers) but not for 2.6.35
>>
>>
>>
>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>> index 5e12462..ce813dd 100644
>> --- a/drivers/net/bonding/bond_main.c
>> +++ b/drivers/net/bonding/bond_main.c
>> @@ -5012,8 +5012,8 @@ int bond_create(struct net *net, const char *name)
>>
>> rtnl_lock();
>>
>> - bond_dev = alloc_netdev(sizeof(struct bonding), name ? name : "",
>> - bond_setup);
>> + bond_dev = alloc_netdev_mq(sizeof(struct bonding), name ? name : "",
>> + bond_setup, max(64, nr_cpu_ids));
>> if (!bond_dev) {
>> pr_err("%s: eek! can't alloc netdev!\n", name);
>> rtnl_unlock();
>>
>>
>> --
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>>
> --
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Huh, so you guys are looking at the same issue (only my issue is RPS).
See http://marc.info/?l=linux-netdev&m=127603240621028&w=2. I'm in favor
of dropping the warning when no queues have been allocated.
How about this (see attached).
rtg
--
Tim Gardner tim.gardner@...onical.com
View attachment "0001-net-Print-num_rx_queues-warning-only-when-there-are-.patch" of type "text/x-patch" (1153 bytes)
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