linux-kernel - Re: [RESEND PATCH] sched/debug: Put sched/domains files under the verbose flag

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Date:   Fri, 20 Jan 2023 15:52:55 +0000
From:   Valentin Schneider <vschneid@...hat.com>
To:     Phil Auld <pauld@...hat.com>, linux-kernel@...r.kernel.org
Cc:     gregkh@...uxfoundation.org, mingo@...hat.com,
        vishalc@...ux.vnet.ibm.com, peterz@...radead.org,
        srikar@...ux.vnet.ibm.com, sshegde@...ux.ibm.com,
        vincent.guittot@...aro.org, ritesh.list@...il.com
Subject: Re: [RESEND PATCH] sched/debug: Put sched/domains files under the
 verbose flag

On 19/01/23 10:07, Phil Auld wrote:
> The debug files under sched/domains can take a long time to regenerate,
> especially when updates are done one at a time. Move these files under
> the sched verbose debug flag. Allow changes to verbose to trigger
> generation of the files. This lets a user batch the updates but still
> have the information available.  The detailed topology printk messages
> are also under verbose.
>
> Discussion that lead to this approach can be found in the link below.
>
> Simplified code to maintain use of debugfs bool routines suggested by
> Michael Ellerman <mpe@...erman.id.au>.
>
> Signed-off-by: Phil Auld <pauld@...hat.com>
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Peter Zijlstra (Intel) <peterz@...radead.org>
> Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
> Cc: Valentin Schneider <vschneid@...hat.com>
> Cc: Vishal Chourasia <vishalc@...ux.vnet.ibm.com>
> Cc: Vincent Guittot <vincent.guittot@...aro.org>
> Link: https://lore.kernel.org/all/Y01UWQL2y2r69sBX@li-05afa54c-330e-11b2-a85c-e3f3aa0db1e9.ibm.com/

Small nits below, other than that:

Reviewed-by: Valentin Schneider <vschneid@...hat.com>

> @@ -402,15 +440,23 @@ void update_sched_domain_debugfs(void)
>       if (!debugfs_sched)
>               return;
>
> +	if (!sched_debug_verbose)
> +		return;
> +
>       if (!cpumask_available(sd_sysctl_cpus)) {
>               if (!alloc_cpumask_var(&sd_sysctl_cpus, GFP_KERNEL))
>                       return;
>               cpumask_copy(sd_sysctl_cpus, cpu_possible_mask);
>       }
>
> -	if (!sd_dentry)
> +	if (!sd_dentry) {
>               sd_dentry = debugfs_create_dir("domains", debugfs_sched);
>
> +		/* rebuild sd_sysclt_cpus if empty since it gets cleared below */
                           ^^^^^^^^^^^^^^
Nit: sd_sysctl_cpus

> +		if (cpumask_first(sd_sysctl_cpus) >=  nr_cpu_ids)

Use cpumask_empty() instead?

> +			cpumask_copy(sd_sysctl_cpus, cpu_online_mask);
> +	}
> +
>       for_each_cpu(cpu, sd_sysctl_cpus) {
>               struct sched_domain *sd;
>               struct dentry *d_cpu;
> --
> 2.31.1