From: HAYASAKA Mitsuo <mitsuo.hayasaka.hu@hitachi.com>
To: Herbert Xu <herbert@gondor.apana.org.au>,
Stephen Hemminger <shemminger@vyatta.com>
Cc: "Patrick McHardy" <kaber@trash.net>,
"David S. Miller" <davem@davemloft.net>,
"Eric Dumazet" <eric.dumazet@gmail.com>,
MichałMirosław <mirq-linux@rere.qmqm.pl>,
"Tom Herbert" <therbert@google.com>,
"Jesse Gross" <jesse@nicira.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
yrl.pp-manager.tt@hitachi.com
Subject: Re: [PATCH net-next ] Fix time-lag of IFF_RUNNING flag consistency between vlan and real devices
Date: Sun, 28 Aug 2011 22:20:41 +0900 [thread overview]
Message-ID: <4E5A40A9.2000404@hitachi.com> (raw)
In-Reply-To: <20110826064553.GA5874@gondor.apana.org.au>
Hi Stephen and Herbert
Thank you for your comments.
(2011/08/26 15:08), Stephen Hemminger wrote:
> I don't think this is the right way to solve the problem.
>
> The flags are supposed to propagate back from real device to vlan
> via network notifications.
>
> Just doing this for ioctl is not enough, API's other than user space depend on this.
> Also the user may have manually set different flags on vlan than on
> the real device.
I agreed.
I will try another way to solve this problem, as you said.
(2011/08/26 15:45), Herbert Xu wrote:
> On Thu, Aug 25, 2011 at 11:08:59PM -0700, Stephen Hemminger wrote:
>> Just doing this for ioctl is not enough, API's other than user space depend on this.
>> Also the user may have manually set different flags on vlan than on
>> the real device.
> Right, anything that tests netif_carrier_ok directly on the VLAN
> device will still be delayed.
>
> Now I remember discussing this issue in Japan. However, I can't
> recall the exact scenario in which the delay occured.
>
> Is the issue with the link status going down on the real device,
> or the real device coming up?
>
> IIRC we already have mechanisms in place to ensure that down events
> are not delayed by linkwatch. Of course it is possible that this
> isn't working for some reason, or some other part of the system is
> causing the delay.
>
> So please clarify the scenario for us Hayasaka-san. Also please
> let us know how you measured the delay.
>
> Thanks,
This issue happens when the link status is going down on the real
device.
ex) A cable is broken, or is unplugged from a NIC.
I measured the delay using ioctl with SIOCGIFFLAGS from userspace
in order to check if there is a time-lag of the flag between vlan
and real devices.
Also, you can check it using a script below.
-------------------------
#!/bin/sh
t=0
while :
do
echo $t; t=$((t+1))
echo -n real; ifconfig RealDev | grep UP
echo -n vlan; ifconfig VlanDev | grep UP
sleep 0.2
done
-------------------------
The result is shown as follows.
It is observed that there is a time-lag of RUNNING status between
real and vlan devices.
....
19
real UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
20
real UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 * A cable is unplugged from NIC.
21
real UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
22
real UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
23
real UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
24
real UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
25
real UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
26
real UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
27
real UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
28
real UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
29
real UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
30
real UP BROADCAST MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
31
real UP BROADCAST MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
32
real UP BROADCAST MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
33
real UP BROADCAST MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
34
real UP BROADCAST MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
35
real UP BROADCAST MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST MULTICAST MTU:1500 Metric:1
36
real UP BROADCAST MULTICAST MTU:1500 Metric:1
vlan UP BROADCAST MULTICAST MTU:1500 Metric:1
Thanks.
next prev parent reply other threads:[~2011-08-28 13:20 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-26 6:02 [PATCH net-next ] Fix time-lag of IFF_RUNNING flag consistency between vlan and real devices Mitsuo Hayasaka
2011-08-26 6:08 ` Stephen Hemminger
2011-08-26 6:45 ` Herbert Xu
2011-08-28 13:20 ` HAYASAKA Mitsuo [this message]
2011-08-28 14:09 ` Eric Dumazet
2011-08-29 6:06 ` Stephen Hemminger
2011-08-29 6:23 ` Eric Dumazet
2011-08-29 6:34 ` David Miller
2011-08-31 9:31 ` [PATCH net-next] net: linkwatch: allow vlans to get carrier changes faster Eric Dumazet
2011-09-01 11:53 ` HAYASAKA Mitsuo
2011-09-15 19:44 ` David Miller
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