[jboss-jira] [JBoss JIRA] (JGRP-2453) Change default TOS for UDP

[Bela Ban (Jira)]

     [ https://issues.redhat.com/browse/JGRP-2453?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bela Ban updated JGRP-2453:
---------------------------
    Fix Version/s: 5.0
                   4.2.0


> Change default TOS for UDP
> --------------------------
>
>                 Key: JGRP-2453
>                 URL: https://issues.redhat.com/browse/JGRP-2453
>             Project: JGroups
>          Issue Type: Enhancement
>    Affects Versions: 4.1.9, 4.0.22
>            Reporter: Dan Berindei
>            Assignee: Bela Ban
>            Priority: Major
>             Fix For: 5.0, 4.2.0
>
>
> The Linux kernel has some fairly sophisticated queueing disciplines like {{fq_codel}}, but the default one is {{pfifo_fast}}.
> {quote}
> pfifo_fast is like three tc-pfifo(8) queues side by side,
>        where packets can be enqueued in any of the three bands based on
>        their Type of Service bits or assigned priority.
>        Not all three bands are dequeued simultaneously - as long as lower
>        bands have traffic, higher bands are never dequeued. This can be used
>        to prioritize interactive traffic or penalize 'lowest cost' traffic.
> ??[http://man7.org/linux/man-pages/man8/tc-pfifo_fast.8.html#ALGORITHM]??
> {quote}
> These are some examples of band mappings:
> {quote}
> {noformat}
> TOS     Bits  Means                    Linux Priority    Band
> ------------------------------------------------------------
> 0x0     0     Normal Service           0 Best Effort     1
> 0x8     4     Maximize Throughput      2 Bulk            2
> 0x10    8     Minimize Delay           6 Interactive     0
> 0x18    12    mt+md                    4 Int. Bulk       1
> {noformat}
> ??[http://man7.org/linux/man-pages/man8/tc-prio.8.html#QDISC_PARAMETERS]??
> {quote}
> By default {{UDP.tos="8"}}, which makes all UDP traffic go into band 2, lowest priority (bulk).
> {{FD_ALL}} and {{FD_ALL2}} heartbeats are {{UDP}} traffic, and in some of our benchmarks there is enough 
> client-server traffic in band 1 to delay the FD_ALL heartbeats for more than 10 seconds. 
> We could either set the default TOS to {{0}} (best effort), or {{0x18}} (maximize throughput + minimize delay), the result is the same: band 1. 



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