Subject: Re: [vserver] Re: How do I stop a high guest CPU load and ifb0 from dropping internet packets?
From: Herbert Poetzl <herbert@13thfloor.at>
Date: Fri, 16 Aug 2013 13:31:49 +0200

On Wed, Aug 14, 2013 at 03:31:44PM +1000, Fog_Watch wrote:
> On Mon, 5 Aug 2013 14:52:07 +1000
> Fog_Watch <db5@exemail.com.au> wrote:

>> What changes are needed to prevent a high guest CPU load, when
>> combined with an IFB ingress interface, from dropping packets?

> Since the last post I've successfully used cpuset to distribute my cores
> so that, I think, my host has one entirely to itself:
> cset: 
>          Name       CPUs-X    MEMs-X Tasks Subs Path
>  ------------ ---------- - ------- - ----- ---- ----------
>          root        0-7 y       0 y   175    4 /
>            as        1-4 n       0 n    61    0 /as
>           kdc          7 n       0 n     2    0 /kdc
>          voip          5 n       0 n    70    0 /voip
>            hf          6 n       0 n    32    0 /hf

> The problem remains.

> When ingress traverses an IFB, with a high host CPU load,
> packets are not dropped, but when a guest CPU load is high
> packets are dropped. 

Okay, what kernel/patch/util-vserver version?

Are network related interrupts routed to the host
only CPU (0 in your case)?

Does it happen on a specific guest?
If so, which guest load triggers it?

> How do I prevent my guest-related packet drops?

Ingress filtering works by dropping packets, so
how do you know that the packets are not dropped
because the limit was reached?

best,
Herbert

> Regards

> Fog_Watch
> -- 
> "A. Because it breaks the logical order of conversation.
>  Q. Why is top posting bad?"