bird under heavy cpu load

[Alexander V. Chernikov]

On 13.03.2012 18:39, Martin Mares wrote:
> Hello!
>
>> This can help CLI interaction (and it is good as temporary solution),
>> but does not decrease time needed for dispatching flapping sessions
>> (particularly if there are many of them).
>
> If you introduce priorities in the event loop, you can make sure that
> flapping sessions cannot disrupt other sessions.
Well, I'm talking mostly not about flapping, bird seems to behave quite 
well. I mean, sometimes it matters if, say, reflector with several 
hundred BGP sessions can take them all up from random states within 1 
(but not 2 or 3 or 4) minutes and continue to work "normally" if half of 
them is flapping. (And here kernel syncer steps in and says "hey, I need 
half of your CPU"). From this point of view any priorities (if I get an 
idea correctly) won't help.
>
> I already thought about event priorities when I wrote the event loop,
> but I finally chose simplicity and decided that priorities can be added
> later if it turns out that they are needed.
>
>> Offloading some activity with low core interaction to another thread can
>> be a good start for offloading another parts of code (protocol messages
>> parsing, sending hello messages, etc..).
>
> I think that once we decide that we need threading, it's better to
> do it once and well. I thought about it some years ago and it seems
> it won't be too complicated.
Can you briefly describe it? I thought about this too, but, 
unfortunately, I can't see the way which does not imply significant core 
complication.
>
>> Moreover, this approach can improve the situation with kernel scan
>
> Wouldn't it be better to get rid of kernel scans completely? :-)
>
Personally I like an idea of having additional independent 
self-healing/controlling process. Disabling it (which is already 
available) is one of possible solutions, but..
> I think they should not be needed on current Linux systems, they are
> there only to make sure that no Netlink packets with updates got dropped.
>
> 				Have a nice fortnight


-- 
WBR, Alexander