From: Peter Zijlstra <peterz@infradead.org>
To: byungchul.park@lge.com
Cc: mingo@kernel.org, linux-kernel@vger.kernel.org,
yuyang.du@intel.com, pjt@google.com, efault@gmx.de,
tglx@linutronix.de
Subject: Re: [PATCH v2 1/2] sched: make each sched class handle its rq assignment in their own class
Date: Wed, 14 Oct 2015 11:00:16 +0200 [thread overview]
Message-ID: <20151014090016.GR17308@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1444812130-17880-2-git-send-email-byungchul.park@lge.com>
On Wed, Oct 14, 2015 at 05:42:09PM +0900, byungchul.park@lge.com wrote:
> +static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
> +{
> + const struct sched_class *class;
> +
> + for_each_class(class) {
> + if (class->set_task_rq)
> + class->set_task_rq(p, cpu);
> + }
> +}
So I worry about this, because the class structures are not all in the
same translation unit, GCC cannot (without -fwhole-program) optimize
that all away.
This means we'll do 5 cacheline loads and 2 indirect calls, on _every_
cpu migration.
next prev parent reply other threads:[~2015-10-14 9:00 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-14 8:42 [PATCH v2 0/2] sched: account fair load avg consistently byungchul.park
2015-10-14 8:42 ` [PATCH v2 1/2] sched: make each sched class handle its rq assignment in their own class byungchul.park
2015-10-14 9:00 ` Peter Zijlstra [this message]
2015-10-14 9:26 ` Byungchul Park
2015-10-14 9:30 ` Peter Zijlstra
2015-10-14 10:16 ` Byungchul Park
2015-10-14 8:42 ` [PATCH v2 2/2] sched: make it possible to account fair class load avg consistently byungchul.park
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