Re: [Xen-devel] [Xen-users] vif-bridge errors when creating and destroying dozens of VMs simultaneously

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On Wed, May 17, 2017 at 1:46 PM, George Dunlap <george.dunlap@xxxxxxxxxx> wrote:
> On 17/05/17 13:43, Ian Jackson wrote:
>> George Dunlap writes ("Re: [Xen-devel] [Xen-users] vif-bridge errors when 
>> creating and destroying dozens of VMs simultaneously"):
>>> So we have three options:
>> ...
>>> 3. Try to check to see if the version of iptables we have supports -w,
>>> and use it if available.  This should also work on all systems, but
>>> introduces a bit of complication.  It also doesn't allow us to
>>> reliably use a timeout.
>>
>> I think this is best.  Eventually we can get rid of the check for -w.
>>
>> I think a timeout in this context is not very helpful.
>>
>> Also, a loop, on a busy system, might need to have many attempts,
>> because it will be polling.
>
> FWIW the iptables internal mechanism will try to grab the lock, and if
> it fails (and -w is set), will call sleep(1) before trying again.  My
> bash loop would do exactly the same thing.
>
> But I agree that if timeouts are not important, doing it via iptables is
> probably cleaner.  Let me work up a patch.

Antony,

Attached is a patch to add the -w option if it's available.  I've
smoke-tested that it works under normal conditions; but my simplistic
attempts to get the bug to trigger have failed.  Can you give it a try
and see if it works?

Thanks,
 -George

Attachment: 0001-vif-common.sh-Have-iptables-wait-for-the-xtables-loc.patch
Description: Text Data

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