[ovs-dev] [PATCH] ovsdb: Add new column to set the maximum number of worker threads

[Ethan Jackson]

> From my understanding, we the upcall dispatcher-handler for each type of
> datapath. So, we may require user to specify the type of datapath (or not
> when there is only one datapath).

In practice users effectively run only one type of datapath.  You
aren't going to have production switches which are running both the
linux kernel and the linux userspace datapath for example.  If someone
is odd enough to do that, they'll end up with twice as many worker
threads as they expected, which doesn't seem like much of a problem to
me.  For this reason I think the simplest thing to do is keep the
configuration parameter in the Open vSwitch table as originally
planned.  Perhaps we should document in the database man page that the
n_workers configuration is per datapath not global to the switch.

> So, it is not appropriate to use a vsctl command. Instead, I'd like to
> implement it as a "appctl dpif/set-n-handler-threads" command.

The problem with this is ovs-appctl settings are persisted in the
database, so they're reset whenever the switch is restarted (on system
boot or upgrade for example).  I expect that most users will have some
prefered number of threads which they want to set once in the database
and then forget about.  appctl is a bit of a pain for that.

Ethan
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