Re: [PATCH v4 7/7] x86/resctrl: Add debug files when mounted with debug option

Ilpo Järvinen
2023-04-20T09:05:55Z

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On Wed, 19 Apr 2023, Moger, Babu wrote:

>
>
> On 4/19/23 08:20, Ilpo Järvinen wrote:
> > On Mon, 17 Apr 2023, Babu Moger wrote:
> >
> >> Add the debug files to the resctrl hierarchy.
> >>
> >> Signed-off-by: Babu Moger <babu.moger@amd.com>
> >> ---
> >> arch/x86/kernel/cpu/resctrl/internal.h | 1 +
> >> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 54 +++++++++++++++++++++++++++++++-
> >> 2 files changed, 54 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> >> index 1eac07ebc31b..855109abb480 100644
> >> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> >> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> >> @@ -288,6 +288,7 @@ struct rdtgroup {
> >> #define RFTYPE_TOP BIT(4)
> >> #define RFTYPE_RES_CACHE BIT(5)
> >> #define RFTYPE_RES_MB BIT(6)
> >> +#define RFTYPE_DEBUG BIT(7)
> >> #define RFTYPE_CTRL_INFO (RFTYPE_INFO | RFTYPE_CTRL)
> >> #define RFTYPE_MON_INFO (RFTYPE_INFO | RFTYPE_MON)
> >> #define RFTYPE_TOP_INFO (RFTYPE_INFO | RFTYPE_TOP)
> >> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> >> index 15ded0dd5b09..1ec4359348c2 100644
> >> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> >> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> >> @@ -1880,6 +1880,7 @@ static struct rftype res_common_files[] = {
> >> .mode = 0444,
> >> .kf_ops = &rdtgroup_kf_single_ops,
> >> .seq_show = rdtgroup_rmid_show,
> >> + .fflags = RFTYPE_BASE | RFTYPE_DEBUG,
> >> },
> >> {
> >> .name = "schemata",
> >> @@ -1909,6 +1910,7 @@ static struct rftype res_common_files[] = {
> >> .mode = 0444,
> >> .kf_ops = &rdtgroup_kf_single_ops,
> >> .seq_show = rdtgroup_closid_show,
> >> + .fflags = RFTYPE_CTRL_BASE | RFTYPE_DEBUG,
> >> },
> >>
> >> };
> >> @@ -2420,6 +2422,49 @@ static int mkdir_mondata_all(struct kernfs_node *parent_kn,
> >> struct rdtgroup *prgrp,
> >> struct kernfs_node **mon_data_kn);
> >>
> >> +static void resctrl_add_debug_files(void)
> >> +{
> >> + struct rftype *rfts, *rft;
> >> + int len;
> >> +
> >> + rfts = res_common_files;
> >> + len = ARRAY_SIZE(res_common_files);
> >> +
> >> + lockdep_assert_held(&rdtgroup_mutex);
> >> +
> >> + for (rft = rfts; rft < rfts + len; rft++) {
> >> + if (rft->fflags & RFTYPE_DEBUG) {
> >> + rft->fflags &= ~RFTYPE_DEBUG;
> >
> > I don't fully follow why you need to play with ->fflags like this.
> >
> > Is it for the ->fflags test in rdtgroup_add_files()? Can't you just do
> > some extra masking there for RFTYPE_DEBUG based on resctrl_debug which
> > you already keep?
>
> Actually with this change, I can remove all these tricks here.
> I don't have to change the check "if (rft->fflags && ((fflags &
> rft->fflags) == rft->fflags)) {"
>
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 1ec4359348c2..b560c44817bb 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -1925,6 +1925,9 @@ static int rdtgroup_add_files(struct kernfs_node
> *kn, unsigned long fflags)
>
> lockdep_assert_held(&rdtgroup_mutex);
>
> + if (resctrl_debug)
> + fflags |= RFTYPE_DEBUG;

Yes, looks good.

It matches to the idea I had in my mind but doesn't require putting it
into the if condition itself.

> +
> for (rft = rfts; rft < rfts + len; rft++) {
> if (rft->fflags && ((fflags & rft->fflags) == rft->fflags)) {
> ret = rdtgroup_add_file(kn, rft);
>
>
> >
> >> + rdtgroup_add_file(rdtgroup_default.kn, rft);
> >> + }
> >> + }

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i.