From: Peter Zijlstra <peterz@infradead.org>
To: Mike Turquette <mturquette@linaro.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>,
mingo@redhat.com, dietmar.eggemann@arm.com, pjt@google.com,
bsegall@google.com, vincent.guittot@linaro.org,
nicolas.pitre@linaro.org, rjw@rjwysocki.net,
linux-kernel@vger.kernel.org, tuukka.tikkanen@linaro.org
Subject: Re: [PATCH RFC 1/2] sched: cfs: introduce capacity_ops
Date: Wed, 8 Oct 2014 10:37:21 +0200 [thread overview]
Message-ID: <20141008083721.GE10832@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <1412749572-29449-2-git-send-email-mturquette@linaro.org>
On Tue, Oct 07, 2014 at 11:26:11PM -0700, Mike Turquette wrote:
> +struct capacity_ops {
> + unsigned long (*get_capacity)(int cpu);
> + spinlock_t lock;
> +};
Yeah, fail there. Ops vectors should not contain serialization, that
simply doesn't work. It means you cannot switch the entire vector out.
Secondly, I dislike this because indirect function calls are more
expensive than direct calls.
> +static unsigned long cfs_get_capacity(int cpu)
> {
> - return default_scale_load_capacity(cpu);
> + unsigned long ret;
> +
> + rcu_read_lock();
> + ret = cfs_capacity_ops.get_capacity(cpu);
> + rcu_read_unlock();
> +
> + return ret;
> +}
So ideally we'd never change these things, so rcu or whatnot should not
be required.
> +/**
> + * set_default_capacity_ops - reset capacity ops to their default
> + * @eops - capacity_ops we are reseting
> + *
> + * Useful for loadable modules that supply custom capacity_ops callbacks. When
> + * unloading these modules need to restore the originals before the custom
> + * callbacks disappear.
Yeah, like hell no. We do not want modules to affect scheduler
behaviour.
next prev parent reply other threads:[~2014-10-08 8:37 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-22 16:24 [PATCH 0/7] sched: Scale-invariant per-entity load-tracking Morten Rasmussen
2014-09-22 16:24 ` [PATCH 1/7] sched: Introduce scale-invariant load tracking Morten Rasmussen
2014-09-25 13:48 ` Vincent Guittot
2014-09-25 17:23 ` Morten Rasmussen
2014-09-26 7:36 ` Vincent Guittot
2014-09-26 9:38 ` Morten Rasmussen
2014-10-02 20:34 ` Peter Zijlstra
2014-10-08 11:00 ` Morten Rasmussen
2014-10-08 11:21 ` Vincent Guittot
2014-10-08 13:53 ` Morten Rasmussen
2014-10-08 14:08 ` Vincent Guittot
2014-10-08 14:16 ` Morten Rasmussen
2014-10-08 11:38 ` Vincent Guittot
2014-10-08 14:05 ` Morten Rasmussen
2014-10-10 9:07 ` Peter Zijlstra
2014-10-08 0:50 ` Yuyang Du
2014-10-08 12:54 ` Dietmar Eggemann
2014-10-10 9:16 ` Peter Zijlstra
2014-10-10 9:14 ` Peter Zijlstra
2014-09-22 16:24 ` [PATCH 2/7] cpufreq: Architecture specific callback for frequency changes Morten Rasmussen
2014-10-08 6:07 ` Mike Turquette
2014-10-08 6:26 ` [PATCH RFC 0/2] introduce capacity_ops to CFS Mike Turquette
2014-10-08 6:26 ` [PATCH RFC 1/2] sched: cfs: introduce capacity_ops Mike Turquette
2014-10-08 8:37 ` Peter Zijlstra [this message]
[not found] ` <20141008232836.4379.3339@quantum>
2014-10-09 9:00 ` Peter Zijlstra
[not found] ` <20141009173433.4379.58492@quantum>
2014-10-09 19:00 ` Peter Zijlstra
2014-10-08 6:26 ` [PATCH RFC 2/2] cpufreq: arm_big_little: provide cpu capacity Mike Turquette
2014-10-08 15:48 ` Morten Rasmussen
[not found] ` <20141008223732.4379.78047@quantum>
2014-10-09 9:02 ` Peter Zijlstra
[not found] ` <20141009172513.4379.56718@quantum>
2014-10-09 17:38 ` Peter Zijlstra
2014-09-22 16:24 ` [PATCH 3/7] arm: Frequency invariant scheduler load-tracking support Morten Rasmussen
2014-09-22 16:24 ` [PATCH 4/7] arm: Micro-architecture invariant load tracking support Morten Rasmussen
2014-09-22 16:24 ` [PATCH 5/7] sched: Implement usage tracking Morten Rasmussen
2014-09-22 16:24 ` [PATCH 6/7] sched: Make sched entity usage tracking scale-invariant Morten Rasmussen
2014-09-22 17:13 ` bsegall
2014-09-23 13:35 ` Morten Rasmussen
2014-10-02 21:04 ` Peter Zijlstra
2014-09-22 16:24 ` [PATCH 7/7] sched: Track sched_entity usage contributions Morten Rasmussen
2014-09-22 17:09 ` bsegall
2014-09-23 13:59 ` Morten Rasmussen
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