[ClusterLabs Developers] New challenges with corosync 3/kronosnet + pacemaker

[Jan Friesse]

Ken Gaillot napsal(a):
> On Fri, 2018-02-09 at 12:52 -0500, Digimer wrote:
>> On 2018-02-09 03:27 AM, Jan Pokorný wrote:
>>> Hello,
>>>
>>> there is certainly whole can of these worms, put first that crosses
>>> my mind: performing double (de)compression on two levels of
>>> abstraction
>>> in the inter-node communication is not very clever, to put it
>>> mildly.
>>>
>>> So far, just pacemaker was doing that for itself under certain
>>> conditions, now corosync 3 will have it's iron in this fire through
>>> kronosnet, too.  Perhaps something to keep in mind to avoid
>>> exercises in futility.
>>
>> Can pacemaker be told to not do compression? If not, can that be
>> added
>> in pacemaker v2?
> 
> Or better yet, is there some corosync API call we can use to determine
> whether corosync/knet is using compression?

Sure. Just read "totem.knet_compression_model" cmap key. If it doesn't 
exists or is "none", compression is disabled.

Honza

> 
> There's currently no way to turn compression off in Pacemaker, however
> it is only used for IPC messages that pass a fairly high size
> threshold, so many clusters would be unaffected even without changes.
>