qio: Allow changing limits dynamically
authorBarret Rhoden <brho@cs.berkeley.edu>
Mon, 19 Jun 2017 15:03:33 +0000 (11:03 -0400)
committerBarret Rhoden <brho@cs.berkeley.edu>
Thu, 20 Jul 2017 12:19:46 +0000 (08:19 -0400)
commit2ed8180f504d797a8e7d314c62dd4e7cadda4d85
treea48544cf4bc635705b641118f61c977167b923f8
parentd4b443e69cc232f92fffb84ba402358e5481dc0a
qio: Allow changing limits dynamically

The queue's limit is the point at which writers get blocked.  Specifically,
they block once the qlen crosses the limit - the actual write succeeds.

The tricky bit is that if you increase the limit, some writers may become
unblocked.  Similarly, the queue may become writable, which requires us to
fire a tap.

Signed-off-by: Barret Rhoden <brho@cs.berkeley.edu>
kern/include/ns.h
kern/src/ns/qio.c