linux-kernel - Re: [PATCH] sched: dynamic config sd

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Message-ID: <20220315092911.GD8939@worktop.programming.kicks-ass.net>
Date:   Tue, 15 Mar 2022 10:29:11 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Qing Wang <wangqing@...o.com>
Cc:     Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Sudeep Holla <sudeep.holla@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org
Subject: Re: [PATCH] sched: dynamic config sd_flags if described in DT

On Tue, Mar 15, 2022 at 12:58:54AM -0700, Qing Wang wrote:
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -1527,6 +1527,7 @@ sd_init(struct sched_domain_topology_level *tl,
>  	struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
>  	int sd_id, sd_weight, sd_flags = 0;
>  	struct cpumask *sd_span;
> +	int ret;
>  
>  #ifdef CONFIG_NUMA
>  	/*
> @@ -1539,6 +1540,15 @@ sd_init(struct sched_domain_topology_level *tl,
>  
>  	if (tl->sd_flags)
>  		sd_flags = (*tl->sd_flags)();
> +
> +#ifdef CONFIG_GENERIC_ARCH_TOPOLOGY
> +	ret = cpus_share_self_cache(cpu_map);
> +	if (ret == 1)
> +		sd_flags |= SD_SHARE_PKG_RESOURCES;
> +	else if (ret == 0)
> +		sd_flags &= ~SD_SHARE_PKG_RESOURCES;
> +#endif
> +
>  	if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
>  			"wrong sd_flags in topology description\n"))
>  		sd_flags &= TOPOLOGY_SD_FLAGS;

Still NAK, you don't have to touch generic code for any of this.