Messages in this thread | | | Subject | Re: [PATCH] sched: fix cpupri hotplug support | From | Peter Zijlstra <> | Date | Wed, 04 Jun 2008 16:42:28 +0200 |
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On Wed, 2008-06-04 at 08:28 -0600, Gregory Haskins wrote:
> >> diff --git a/include/linux/sched.h b/include/linux/sched.h > >> index bb71371..9c5b8c9 100644 > >> --- a/include/linux/sched.h > >> +++ b/include/linux/sched.h > >> @@ -970,6 +970,8 @@ struct sched_class { > >> > >> void (*join_domain)(struct rq *rq); > >> void (*leave_domain)(struct rq *rq); > >> + void (*online)(struct rq *rq); > >> + void (*offline)(struct rq *rq); > > > > Rather unfortunate to add yet another two callbacks, can't this be done > > with a creative use of leave/join? > > Yeah, I was debating how to do this. In fact, as you can see the > implementation of join/online and leave/offline is identical. I wasnt > sure if putting a join/leave in the hotplug code made sense, so I > added a new callback that maps to the same logic. Perhaps what I > should have done was to s/join/online and s/leave/offline and fixed > the root-domain code to use the online/offline variant. I like this > better so I will put out a v2 patch in a few minutes. >
> I think you are misinterpreting that part. leave/join is fully > functional and intact. I just merged the two implementations to call > one function (see the sched_class assignment below) > > > > >> @@ -1278,8 +1284,10 @@ const struct sched_class rt_sched_class = { > >> .load_balance = load_balance_rt, > >> .move_one_task = move_one_task_rt, > >> .set_cpus_allowed = set_cpus_allowed_rt, > >> - .join_domain = join_domain_rt, > >> - .leave_domain = leave_domain_rt, > >> + .join_domain = rq_online_rt, > >> + .leave_domain = rq_offline_rt, > >> + .online = rq_online_rt, > >> + .offline = rq_offline_rt, > >> .pre_schedule = pre_schedule_rt, > >> .post_schedule = post_schedule_rt, > >> .task_wake_up = task_wake_up_rt,
Ah, right - I missed that.
Right - I was just looking to get the cpu-down path to do one ->leave() extra (aside from leave/join the def_root_domain) so it's basically unattached - which makes sense for a downed cpu.
Conversely the cpu-up should start with an extra ->join() attaching the downed cpu again.
I'm thinking doing it that way saves us the extra callbacks. We can do those if and when the leave/offline behaviour actually divert.
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