On Thu, Aug 24, 2017 at 07:37:32AM +0800, Fam Zheng wrote: > On Wed, 08/23 18:44, Dr. David Alan Gilbert wrote: > > * Peter Xu (pet...@redhat.com) wrote: > > > Introducing this new parameter for QMP commands in general to mark out > > > when the command does not need BQL. Normally QMP command executions are > > > done with the protection of BQL in QEMU. However the truth is that not > > > all the QMP commands require the BQL. > > > > > > This new parameter provides a way to allow QMP commands to run in > > > parallel when possible, without the contention on the BQL. > > > > > > Since the default value of "without-bql" is still false, so now all QMP > > > commands are still protected by BQL still. > > > > > > Signed-off-by: Peter Xu <pet...@redhat.com> > > > > We should define what a 'without-bql' command is allowed to do: > > 'Commands that have without-bql set _may_ be called without the bql > > being taken. They must not take the bql or any other lock that may > > become dependent on the bql.'
Sure. > > (Do we need to say anything about RCU?) Could I ask how is RCU related? > > > > Also, 'no-bql' is shorter :-) > > Or rather "need-bql" that defaults to true to avoid double negative (TM) with > "no-bql = false"? Ok let me use "need-bql". :) -- Peter Xu
