Date: Fri, 10 Oct 2014 19:06:42 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>, Steven Rostedt <rostedt@goodmis.org>,
        linux-kernel@vger.kernel.org, Kirill Tkhai <tkhai@yandex.ru>
Subject: Re: [PATCH 1/1] sched: make finish_task_switch() return struct rq *
Message-ID: <20141010170641.GB14401@redhat.com>
References: <20141007195046.GA28002@redhat.com> <20141009193207.GA5408@redhat.com> <20141009193232.GB5408@redhat.com> <20141010100643.GI10832@worktop.programming.kicks-ass.net>
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On 10/10, Peter Zijlstra wrote:
>
> On Thu, Oct 09, 2014 at 09:32:32PM +0200, Oleg Nesterov wrote:
> > @@ -2802,15 +2802,8 @@ need_resched:
> >  		rq->curr = next;
> >  		++*switch_count;
> >
> > -		context_switch(rq, prev, next); /* unlocks the rq */
> > -		/*
> > -		 * The context switch have flipped the stack from under us
> > -		 * and restored the local variables which were saved when
> > -		 * this task called schedule() in the past. prev == current
> > -		 * is still correct, but it can be moved to another cpu/rq.
> > -		 */
> > -		cpu = smp_processor_id();
> > -		rq = cpu_rq(cpu);
> > +		rq = context_switch(rq, prev, next); /* unlocks the rq */
> > +		cpu = rq->cpu;
>
> This won't compile on UP, cpu_of(rq) works though.

Heh ;) and I swear I was going to write cpu_of().

and I agree with BUG_ON() in __trace_sched_switch() if CONFIG_SCHED_DEBUG.

I am travelling till next Wednesday, will resend everything once I return.

Thanks a lot!

Oleg.

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