Re: [Qemu-devel] monitor: enable OOB by default

From: Markus Armbruster <armbru@redhat.com>
To: Peter Xu <peterx@redhat.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] monitor: enable OOB by default
Date: Wed, 27 Jun 2018 15:13:57 +0200	[thread overview]
Message-ID: <87h8lo74oa.fsf@dusky.pond.sub.org> (raw)
In-Reply-To: <87wouk8vul.fsf@dusky.pond.sub.org> (Markus Armbruster's message of "Wed, 27 Jun 2018 10:41:38 +0200")

Monitor behavior changes even when the client rejects capability "oob".

Traditionally, the monitor reads, executes and responds to one command
after the other.  If the client sends in-band commands faster than the
server can execute them, the kernel will eventually refuse to buffer
more, and sending blocks or fails with EAGAIN.

To make OOB possible, we need to read and queue commands as we receive
them.  If the client sends in-band commands faster than the server can
execute them, the server will eventually drop commands to limit the
queue length.  The sever sends event COMMAND_DROPPED then.

However, we get the new behavior even when the client rejects capability
"oob".  We get the traditional behavior only when the server doesn't
offer "oob".

Is this what we want?