[ovs-dev] [PATCH] netdev-linux: HFSC in linux

Ben Pfaff blp at nicira.com
Thu Nov 11 17:34:01 UTC 2010


On Wed, Nov 10, 2010 at 04:33:10PM -0800, Ethan Jackson wrote:
> This commit implements the Hierarchical Fair Service Curve queuing
> discipline in linux. HFSC performs better at high bandwidth and
> implements min-rate proportional sharing of excess bandwidth.  Only
> a simplified configuration interface is exposed to the user.  This
> can be expand to allow more tweaking in the future.

I compared this just about line-by-line with the equivalent HTB code.
There are few differences, and most of them are stylistic, and in most
of those cases I prefer the way you did it in HFSC anyway.

Of course, the big question is whether we should factor out similar code
somehow.  I'm happy to defer that, though, until we delete the htb code
or until we add a third almost-identical implementation, whichever comes
first.  That's when it will really be worthwhile.

I saw one use of HTB_N_QUEUES and one use of htb_get__() within the new
code.  I assume that both of those should use the HFSC version instead.

Some of the htb functions have comments above them that describe the
equivalent "tc" commands, but the hfsc code doesn't add similar
comments.  Would you mind doing that, so that for testing and debugging
by hand I don't have to remember the tc syntax?

Since the configuration is simplified, would it be OK to delete the "and
how to configure it" phrase in the linux-hfsc description in
vswitch.xml?

Thanks,

Ben.




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