linux-kernel - RE: [PATCH v4 7/7] x86/resctrl: Add debug files when mounted with debug option

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Message-ID: <MW3PR12MB4553359D41816826AA001A1095609@MW3PR12MB4553.namprd12.prod.outlook.com>
Date:   Fri, 21 Apr 2023 18:47:58 +0000
From:   "Moger, Babu" <Babu.Moger@....com>
To:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
CC:     "corbet@....net" <corbet@....net>,
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Subject: RE: [PATCH v4 7/7] x86/resctrl: Add debug files when mounted with
 debug option

[AMD Official Use Only - General]



> -----Original Message-----
> From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> Sent: Thursday, April 20, 2023 3:59 AM
> To: Moger, Babu <Babu.Moger@....com>
> Cc: corbet@....net; Reinette Chatre <reinette.chatre@...el.com>;
> tglx@...utronix.de; mingo@...hat.com; bp@...en8.de; fenghua.yu@...el.com;
> dave.hansen@...ux.intel.com; x86@...nel.org; hpa@...or.com;
> paulmck@...nel.org; akpm@...ux-foundation.org; quic_neeraju@...cinc.com;
> rdunlap@...radead.org; damien.lemoal@...nsource.wdc.com;
> songmuchun@...edance.com; peterz@...radead.org; jpoimboe@...nel.org;
> pbonzini@...hat.com; chang.seok.bae@...el.com;
> pawan.kumar.gupta@...ux.intel.com; jmattson@...gle.com;
> daniel.sneddon@...ux.intel.com; Das1, Sandipan <Sandipan.Das@....com>;
> tony.luck@...el.com; james.morse@....com; linux-doc@...r.kernel.org;
> LKML <linux-kernel@...r.kernel.org>; bagasdotme@...il.com;
> eranian@...gle.com; christophe.leroy@...roup.eu; jarkko@...nel.org;
> adrian.hunter@...el.com; quic_jiles@...cinc.com; peternewman@...gle.com
> Subject: Re: [PATCH v4 7/7] x86/resctrl: Add debug files when mounted with
> debug option
> 
> 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@....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.
Without if condition?  How?  Let me know.
Thanks
Babu