On 05/01/2018 13:11, Slawa Olhovchenkov wrote:
On Fri, Jan 05, 2018 at 03:50:31AM +0700, Eugene Grosbein wrote:
05.01.2018 3:05, Steven Hartland wrote:
Author: smh
Date: Thu Jan 4 20:05:47 2018
New Revision: 327559
URL: https://svnweb.freebsd.org/changeset/base/327559
Log:
Disabled the use of flowid for lagg by default
Disabled the use of RSS hash from the network card aka flowid for
lagg(4) interfaces by default as it's currently incompatible with
the lacp and loadbalance protocols.
The incompatibility is due to the fact that the flowid isn't know
for the first packet of a new outbound stream which can result in
the hash calculation method changing and hence a stream being
incorrectly split across multiple interfaces during normal
operation.
This can be re-enabled by setting the following in loader.conf:
net.link.lagg.default_use_flowid="1"
Discussed with: kmacy
Sponsored by: Multiplay
RSS by definition has meaning to received stream. What is "outbound" stream
in this context, why can the hash calculatiom method change and what exactly
does it mean "a stream being incorrectly split"?
Defaults should not be changed so easily just because they are not optimal
for some specific case. Each lagg has its own setting for flowid usage
and why one cannot just use "ifconfig lagg0 -use_flowid" for such cases?
Irrelevant to RSS and etc. flowid distribution in lacp case work very
bad. This is good and must be MFC (IMHO).
There was no concrete conclusion to this thread and I've not had time to
look into this more and it's on my open list to MFC to stable/11 in time
for 11.2.
Even given the drop in performance, I think we should prefer correctness
over increased performance and given the new default can still be
overridden in loader.conf I'm looking to MFC this shortly unless I get
any strong objections with a clear path forward.
Regards
Steve
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