Re: [RFC] [PATCH] cgroup: limit network bandwidth

[Andrea Righi]

Paul Menage wrote:
> On Jan 23, 2008 8:48 AM, Andrea Righi <righiandr@xxxxxxxxxxxxxxxxxxxxx> wrote:
>>> 1. Implementation of soft limits (limit on contention of resource)
>>>    gets harder
>> Why? do you mean implementing a grace time when the soft-limit is
>> exceeded? this could be done in cgroup_nl_throttle() introducing 3
>> additional attributes to struct netlimit (i.e. hard_limit,
>> last_time_exceeded grace_time) and perform something like:
>> ...
>>         if ((current_rate > hard_limit) ||
>>             time_after(jiffies, last_time_exceeded + grace_time))
>>                         schedule_timeout(sleep);
>> ...
> 
> He's talking about cases where we want the behaviour to be
> work-conserving, whilst still offering guarantees in the event of
> contention. e.g. cgroups A and B each get a 20% guarantee on the TX
> path if they need it, but anyone can use any otherwise-idle bandwidth.
> (This is relatively straightforward to set up from userspace with the
> standard Linux traffic control tools).

OK.

>> Yes, the integration with iptables (as Paul said), and traffic shaping
>> rules would be absolutely the right way(tm) in perspective. I was just
>> proposing a possible simple API to implement the limiting stuff.
> 
> But this issue (traffic control for cgroups) is too complex to be
> described by a simple API. Any simple API you choose to try to
> describe the limiting directly will be insufficient for a good number
> of the potential users. Better to just provide a (very simple) API to
> hook into the existing (complex) traffic control API and leave the
> tricky stuff to userspace, where anyone can construct arbitrarily
> complex queueing schemes with a shell script and a few calls to "tc".
> 
> Paul
> 

OK, thanks for the clarifications.

-Andrea
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