2020-01-08 14:34:30

by Peter Zijlstra

Subject: Re: [PATCH] sched/psi: create /proc/pressure and /proc/pressure/{io|memory|cpu} only when psi enabled

On Wed, Dec 18, 2019 at 08:38:18PM +0800, Wang Long wrote:
> when CONFIG_PSI_DEFAULT_DISABLED set to N or the command line set psi=0,
> I think we should not create /proc/pressure and
> /proc/pressure/{io|memory|cpu}.
>
> In the future, user maybe determine whether the psi feature is enabled by
> checking the existence of the /proc/pressure dir or
> /proc/pressure/{io|memory|cpu} files.

Works for me; Johannes?

> Signed-off-by: Wang Long <[email protected]>
> ---
> kernel/sched/psi.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
> index 517e371..f12ade2 100644
> --- a/kernel/sched/psi.c
> +++ b/kernel/sched/psi.c
> @@ -1279,10 +1279,12 @@ static int psi_fop_release(struct inode *inode, struct file *file)
>
> static int __init psi_proc_init(void)
> {
> - proc_mkdir("pressure", NULL);
> - proc_create("pressure/io", 0, NULL, &psi_io_fops);
> - proc_create("pressure/memory", 0, NULL, &psi_memory_fops);
> - proc_create("pressure/cpu", 0, NULL, &psi_cpu_fops);
> + if (psi_enable) {
> + proc_mkdir("pressure", NULL);
> + proc_create("pressure/io", 0, NULL, &psi_io_fops);
> + proc_create("pressure/memory", 0, NULL, &psi_memory_fops);
> + proc_create("pressure/cpu", 0, NULL, &psi_cpu_fops);
> + }
> return 0;
> }
> module_init(psi_proc_init);
> --
> 1.8.3.1
>
>
>

2020-01-09 20:10:18

by Johannes Weiner

Subject: Re: [PATCH] sched/psi: create /proc/pressure and /proc/pressure/{io|memory|cpu} only when psi enabled

On Wed, Jan 08, 2020 at 02:55:26PM +0100, Peter Zijlstra wrote:
> On Wed, Dec 18, 2019 at 08:38:18PM +0800, Wang Long wrote:
> > when CONFIG_PSI_DEFAULT_DISABLED set to N or the command line set psi=0,
> > I think we should not create /proc/pressure and
> > /proc/pressure/{io|memory|cpu}.
> >
> > In the future, user maybe determine whether the psi feature is enabled by
> > checking the existence of the /proc/pressure dir or
> > /proc/pressure/{io|memory|cpu} files.
>
> Works for me; Johannes?

Seems reasonable, and the patch looks good to me.

Acked-by: Johannes Weiner <[email protected]>

2020-01-10 13:57:35

by Peter Zijlstra

Subject: Re: [PATCH] sched/psi: create /proc/pressure and /proc/pressure/{io|memory|cpu} only when psi enabled

On Thu, Jan 09, 2020 at 10:30:02AM -0500, Johannes Weiner wrote:
> On Wed, Jan 08, 2020 at 02:55:26PM +0100, Peter Zijlstra wrote:
> > On Wed, Dec 18, 2019 at 08:38:18PM +0800, Wang Long wrote:
> > > when CONFIG_PSI_DEFAULT_DISABLED set to N or the command line set psi=0,
> > > I think we should not create /proc/pressure and
> > > /proc/pressure/{io|memory|cpu}.
> > >
> > > In the future, user maybe determine whether the psi feature is enabled by
> > > checking the existence of the /proc/pressure dir or
> > > /proc/pressure/{io|memory|cpu} files.
> >
> > Works for me; Johannes?
>
> Seems reasonable, and the patch looks good to me.
>
> Acked-by: Johannes Weiner <[email protected]>

Thanks!