lkml.org 
[lkml]   [2009]   [Nov]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 15/20] blkio: Take care of preemptions across groups
    Vivek Goyal wrote:
    > o Additional preemption checks for groups where we travel up the hierarchy
    > and see if one queue should preempt other or not.
    >
    > o Also prevents preemption across groups in some cases to provide isolation
    > between groups.
    >
    > Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
    > ---
    > block/cfq-iosched.c | 33 +++++++++++++++++++++++++++++++++
    > 1 files changed, 33 insertions(+), 0 deletions(-)
    >
    > diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
    > index 87b1799..98dbead 100644
    > --- a/block/cfq-iosched.c
    > +++ b/block/cfq-iosched.c
    > @@ -2636,6 +2636,36 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
    > }
    > }
    >
    > +static bool cfq_should_preempt_group(struct cfq_data *cfqd,
    > + struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
    > +{
    > + struct cfq_entity *cfqe = &cfqq->entity;
    > + struct cfq_entity *new_cfqe = &new_cfqq->entity;
    > +
    > + if (cfqq_to_cfqg(cfqq) != &cfqd->root_group)
    > + cfqe = parent_entity(&cfqq->entity);
    > +
    > + if (cfqq_to_cfqg(new_cfqq) != &cfqd->root_group)
    > + new_cfqe = parent_entity(&new_cfqq->entity);
    > +
    > + /*
    > + * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
    > + */
    > +
    > + if (new_cfqe->ioprio_class == IOPRIO_CLASS_RT
    > + && cfqe->ioprio_class != IOPRIO_CLASS_RT)
    > + return true;
    > + /*
    > + * Allow an BE request to pre-empt an ongoing IDLE clas timeslice.
    > + */
    > +
    > + if (new_cfqe->ioprio_class == IOPRIO_CLASS_BE
    > + && cfqe->ioprio_class == IOPRIO_CLASS_IDLE)
    > + return true;
    > +
    > + return false;
    > +}
    > +
    > /*
    > * Check if new_cfqq should preempt the currently active queue. Return 0 for
    > * no or if we aren't sure, a 1 will cause a preempt.
    > @@ -2666,6 +2696,9 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
    > if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
    > return true;
    >
    > + if (cfqq_to_cfqg(new_cfqq) != cfqq_to_cfqg(cfqq))
    > + return cfq_should_preempt_group(cfqd, cfqq, new_cfqq);
    > +

    Vivek, why not put cfq_should_preempt_group() at the beginning of cfq_should_preempt()
    to prevent preemption across groups?

    --
    Regards
    Gui Jianfeng



    \
     
     \ /
      Last update: 2009-11-06 09:03    [W:7.783 / U:0.352 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site