linux-kernel - Re: [PATCH 12/36] sched_ext: Implement BPF extensible scheduler class

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Message-ID: <ZWMKcPXIAuJ22Q+i@gpd>
Date:   Sun, 26 Nov 2023 10:05:52 +0100
From:   Andrea Righi <andrea.righi@...onical.com>
To:     Tejun Heo <tj@...nel.org>
Cc:     torvalds@...ux-foundation.org, mingo@...hat.com,
        peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com, ast@...nel.org,
        daniel@...earbox.net, andrii@...nel.org, martin.lau@...nel.org,
        joshdon@...gle.com, brho@...gle.com, pjt@...gle.com,
        derkling@...gle.com, haoluo@...gle.com, dvernet@...a.com,
        dschatzberg@...a.com, dskarlat@...cmu.edu, riel@...riel.com,
        changwoo@...lia.com, himadrics@...ia.fr, memxor@...il.com,
        linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
        kernel-team@...a.com
Subject: Re: [PATCH 12/36] sched_ext: Implement BPF extensible scheduler class

On Sat, Nov 25, 2023 at 09:59:43AM -1000, Tejun Heo wrote:
> Hello,
> 
> On Thu, Nov 23, 2023 at 09:07:35AM +0100, Andrea Righi wrote:
> > On Fri, Nov 10, 2023 at 04:47:38PM -1000, Tejun Heo wrote:
> ...
> > > +#ifdef CONFIG_SCHED_CLASS_EXT
> > > +	p->scx.dsq		= NULL;
> > > +	INIT_LIST_HEAD(&p->scx.dsq_node);
> > > +	p->scx.flags		= 0;
> > > +	p->scx.weight		= 0;
> > > +	p->scx.sticky_cpu	= -1;
> > > +	p->scx.holding_cpu	= -1;
> > > +	p->scx.kf_mask		= 0;
> > > +	atomic64_set(&p->scx.ops_state, 0);
> > 
> > We probably need atomic_long_set() here or in 32-bit arches (such as
> > armhf) we get this:
> > 
> > kernel/sched/core.c:4564:22: error: passing argument 1 of ‘atomic64_set’ from incompatible pointer type [-Werror=incompatible-pointer-types]
> >  4564 |         atomic64_set(&p->scx.ops_state, 0);
> >       |                      ^~~~~~~~~~~~~~~~~
> >       |                      |
> >       |                      atomic_long_t * {aka atomic_t *}
> > 
> ...
> > > +static void set_next_task_scx(struct rq *rq, struct task_struct *p, bool first)
> > > +{
> > > +	if (p->scx.flags & SCX_TASK_QUEUED) {
> > > +		WARN_ON_ONCE(atomic64_read(&p->scx.ops_state) != SCX_OPSS_NONE);
> > 
> > Ditto. Even if this line is replaced later by
> > "[PATCH 31/36] sched_ext: Implement core-sched support"
> > 
> > > +		dispatch_dequeue(&rq->scx, p);
> > > +	}
> > > +
> > > +	p->se.exec_start = rq_clock_task(rq);
> > > +}
> 
> Sorry about that. I updated them and will include the changes in the next
> iteration. Will test 32bit build too next time.
> 
> Thanks.

No problem, if you don't I'll test it for you. :)

-Andrea