linux-kernel - RE: [PATCH v11 13/13] Documentation/x86: Update resctrl.rst for new features

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <MW3PR12MB45538E045D655C1D6B3BD02C95FC9@MW3PR12MB4553.namprd12.prod.outlook.com>
Date:   Wed, 11 Jan 2023 22:39:04 +0000
From:   "Moger, Babu" <Babu.Moger@....com>
To:     Reinette Chatre <reinette.chatre@...el.com>,
        "corbet@....net" <corbet@....net>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>
CC:     "fenghua.yu@...el.com" <fenghua.yu@...el.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
        "paulmck@...nel.org" <paulmck@...nel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "quic_neeraju@...cinc.com" <quic_neeraju@...cinc.com>,
        "rdunlap@...radead.org" <rdunlap@...radead.org>,
        "damien.lemoal@...nsource.wdc.com" <damien.lemoal@...nsource.wdc.com>,
        "songmuchun@...edance.com" <songmuchun@...edance.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "jpoimboe@...nel.org" <jpoimboe@...nel.org>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "chang.seok.bae@...el.com" <chang.seok.bae@...el.com>,
        "pawan.kumar.gupta@...ux.intel.com" 
        <pawan.kumar.gupta@...ux.intel.com>,
        "jmattson@...gle.com" <jmattson@...gle.com>,
        "daniel.sneddon@...ux.intel.com" <daniel.sneddon@...ux.intel.com>,
        "Das1, Sandipan" <Sandipan.Das@....com>,
        "tony.luck@...el.com" <tony.luck@...el.com>,
        "james.morse@....com" <james.morse@....com>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "bagasdotme@...il.com" <bagasdotme@...il.com>,
        "eranian@...gle.com" <eranian@...gle.com>,
        "christophe.leroy@...roup.eu" <christophe.leroy@...roup.eu>,
        "jarkko@...nel.org" <jarkko@...nel.org>,
        "adrian.hunter@...el.com" <adrian.hunter@...el.com>,
        "quic_jiles@...cinc.com" <quic_jiles@...cinc.com>,
        "peternewman@...gle.com" <peternewman@...gle.com>
Subject: RE: [PATCH v11 13/13] Documentation/x86: Update resctrl.rst for new
 features

[AMD Official Use Only - General]

Hi Reinette,

> -----Original Message-----
> From: Reinette Chatre <reinette.chatre@...el.com>
> Sent: Wednesday, January 11, 2023 4:07 PM
> To: Moger, Babu <Babu.Moger@....com>; corbet@....net;
> tglx@...utronix.de; mingo@...hat.com; bp@...en8.de
> Cc: 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; 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 v11 13/13] Documentation/x86: Update resctrl.rst for new
> features
> 
> Hi Babu,
> 
> On 1/9/2023 8:44 AM, Babu Moger wrote:
> > Update the documentation for the new features:
> > 1. Slow Memory Bandwidth allocation (SMBA).
> >    With this feature, the QOS  enforcement policies can be applied
> >    to the external slow memory connected to the host. QOS enforcement
> >    is accomplished by assigning a Class Of Service (COS) to a processor
> >    and specifying allocations or limits for that COS for each resource
> >    to be allocated.
> >
> > 2. Bandwidth Monitoring Event Configuration (BMEC).
> >    The bandwidth monitoring events mbm_total_bytes and mbm_local_bytes
> >    are set to count all the total and local reads/writes respectively.
> >    With the introduction of slow memory, the two counters are not
> >    enough to count all the different types of memory events. With the
> >    feature BMEC, the users have the option to configure mbm_total_bytes
> >    and mbm_local_bytes to count the specific type of events.
> >
> > Also add configuration instructions with examples.
> >
> > Signed-off-by: Babu Moger <babu.moger@....com>
> > ---
> >  Documentation/x86/resctrl.rst | 142
> > +++++++++++++++++++++++++++++++++-
> >  1 file changed, 140 insertions(+), 2 deletions(-)
> >
> > diff --git a/Documentation/x86/resctrl.rst
> > b/Documentation/x86/resctrl.rst index 71a531061e4e..2860856f4463
> > 100644
> > --- a/Documentation/x86/resctrl.rst
> > +++ b/Documentation/x86/resctrl.rst
> > @@ -17,14 +17,16 @@ AMD refers to this feature as AMD Platform Quality
> of Service(AMD QoS).
> >  This feature is enabled by the CONFIG_X86_CPU_RESCTRL and the x86
> > /proc/cpuinfo  flag bits:
> >
> > -=============================================
> 	================================
> > +===============================================
> 	================================
> >  RDT (Resource Director Technology) Allocation	"rdt_a"
> >  CAT (Cache Allocation Technology)		"cat_l3", "cat_l2"
> >  CDP (Code and Data Prioritization)		"cdp_l3", "cdp_l2"
> >  CQM (Cache QoS Monitoring)			"cqm_llc",
> "cqm_occup_llc"
> >  MBM (Memory Bandwidth Monitoring)		"cqm_mbm_total",
> "cqm_mbm_local"
> >  MBA (Memory Bandwidth Allocation)		"mba"
> > -=============================================
> 	================================
> > +SMBA (Slow Memory Bandwidth Allocation)         "smba"
> > +BMEC (Bandwidth Monitoring Event Configuration) "bmec"
> > +===============================================
> 	================================
> >
> 
> I expect that you will follow Boris's guidance here and not make these flags
> visible in /proc/cpuinfo. That would imply that this addition will have no entries
> in the second column. Perhaps this could be made easier to parse by using
> empty quotes ("") in the second column to match syntax used in the existing
> flags as well as the cpufeatures.h change?

Hmm.. I thought we dropped that idea for now. Did I miss understand that?
Thanks
Babu 

> 
> If/when making this change, could you please also add a note that documents
> this new guidance for other resctrl developers? Something like below but I am
> looking forward to
> improvements:
> "Historically new features were made visible by default in /proc/cpuinfo. This
> resulted in the flags field becoming hard to parse by humans. Adding a new
> flag to /proc/cpuinfo should be avoided if user space can obtain information
> about the feature from resctrl's info directory."
> 
> The rest of the document looks good to me.
> 
> Thank you
> 
> Reinette