Messages in this thread |  | | Subject | Re: [PATCH v2 tip/core/rcu 6/6] srcu: Document polling interfaces for Tree SRCU grace periods | From | Neeraj Upadhyay <> | Date | Fri, 27 Nov 2020 13:57:10 +0530 |
| |
On 11/21/2020 6:29 AM, paulmck@kernel.org wrote: > From: "Paul E. McKenney" <paulmck@kernel.org> > > This commit adds requirements documentation for the > get_state_synchronize_srcu(), start_poll_synchronize_srcu(), and > poll_state_synchronize_srcu() functions. > > Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/ > Reported-by: Kent Overstreet <kent.overstreet@gmail.com> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > ---
Reviewed-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Thanks Neeraj
> Documentation/RCU/Design/Requirements/Requirements.rst | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst > index 1e3df77..2dce79d 100644 > --- a/Documentation/RCU/Design/Requirements/Requirements.rst > +++ b/Documentation/RCU/Design/Requirements/Requirements.rst > @@ -2600,6 +2600,24 @@ also includes DEFINE_SRCU(), DEFINE_STATIC_SRCU(), and > init_srcu_struct() APIs for defining and initializing > ``srcu_struct`` structures. > > +More recently, the SRCU API has added polling interfaces: > + > +#. start_poll_synchronize_srcu() returns a cookie identifying > + the completion of a future SRCU grace period and ensures > + that this grace period will be started. > +#. poll_state_synchronize_srcu() returns ``true`` iff the > + specified cookie corresponds to an already-completed > + SRCU grace period. > +#. get_state_synchronize_srcu() returns a cookie just like > + start_poll_synchronize_srcu() does, but differs in that > + it does nothing to ensure that any future SRCU grace period > + will be started. > + > +These functions are used to avoid unnecessary SRCU grace periods in > +certain types of buffer-cache algorithms having multi-stage age-out > +mechanisms. The idea is that by the time the block has aged completely > +from the cache, an SRCU grace period will be very likely to have elapsed. > + > Tasks RCU > ~~~~~~~~~ > >
-- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation
|  |