Re: [PATCH v2 06/33] Documentation, x86: Documentation for Intel resource allocation user interface

From	Fenghua Yu <fenghua.yu@intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 06/33] Documentation, x86: Documentation for Intel resource allocation user interface
Date	2016-09-09 06:30 +0200
Message-ID	<sflBU-6IG-17@gated-at.bofh.it> (permalink)
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On Thu, Sep 08, 2016 at 03:45:14PM -0700, Shaohua Li wrote:
> On Thu, Sep 08, 2016 at 06:17:47PM -0700, Fenghua Yu wrote:
> > On Thu, Sep 08, 2016 at 03:01:20PM -0700, Shaohua Li wrote:
> > > On Thu, Sep 08, 2016 at 02:57:00AM -0700, Fenghua Yu wrote:
> > > > From: Fenghua Yu <fenghua.yu@intel.com>
> > > > 
> > > > The documentation describes user interface of how to allocate resource
> > > > in Intel RDT.
> > > > 
> > > > Please note that the documentation covers generic user interface. Current
> > > > patch set code only implemente CAT L3. CAT L2 code will be sent later.
> > > > 
> > > > Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
> > > > Reviewed-by: Tony Luck <tony.luck@intel.com>
> > > > ---
> > > >  Documentation/x86/intel_rdt_ui.txt | 164 +++++++++++++++++++++++++++++++++++++
> > > >  1 file changed, 164 insertions(+)
> > > >  create mode 100644 Documentation/x86/intel_rdt_ui.txt
> > > > 
> > > > diff --git a/Documentation/x86/intel_rdt_ui.txt b/Documentation/x86/intel_rdt_ui.txt
> > > > new file mode 100644
> > > > index 0000000..27de386
> > > > --- /dev/null
> > > > +++ b/Documentation/x86/intel_rdt_ui.txt
> > > > @@ -0,0 +1,164 @@
> > > > +User Interface for Resource Allocation in Intel Resource Director Technology
> > > > +
> > > > +Copyright (C) 2016 Intel Corporation
> > > > +
> > > > +Fenghua Yu <fenghua.yu@intel.com>
> > > > +Tony Luck <tony.luck@intel.com>
> > > > +
> > > > +This feature is enabled by the CONFIG_INTEL_RDT Kconfig and the
> > > > +X86 /proc/cpuinfo flag bits "rdt", "cat_l3" and "cdp_l3".
> > > > +
> > > > +To use the feature mount the file system:
> > > > +
> > > > + # mount -t resctrl resctrl [-o cdp,verbose] /sys/fs/resctrl
> > > > +
> > > > +mount options are:
> > > > +
> > > > +"cdp": Enable code/data prioritization in L3 cache allocations.
> > > > +
> > > > +"verbose": Output more info in the "info" file under info directory
> > > > +	and in dmesg. This is mainly for debug.
> > > > +
> > > > +
> > > > +Resource groups
> > > > +---------------
> > > > +Resource groups are represented as directories in the resctrl file
> > > > +system. The default group is the root directory. Other groups may be
> > > > +created as desired by the system administrator using the "mkdir(1)"
> > > > +command, and removed using "rmdir(1)".
> > > > +
> > > > +There are three files associated with each group:
> > > > +
> > > > +"tasks": A list of tasks that belongs to this group. Tasks can be
> > > > +	added to a group by writing the task ID to the "tasks" file
> > > > +	(which will automatically remove them from the previous
> > > > +	group to which they belonged). New tasks created by fork(2)
> > > > +	and clone(2) are added to the same group as their parent.
> > > > +	If a pid is not in any sub partition, it is in root partition
> > > > +	(i.e. default partition).
> > > Hi Fenghua,
> > > 
> > > Will you add a 'procs' interface to allow move a process into a group? Using
> > > the 'tasks' interface to move process is inconvenient and has race conditions
> > > (eg, some new threads could be escaped).
> > 
> > We don't plan to add a 'procs' interface for rdtgroup. We only use resctrl
> > interface to allocate resources.
> > 
> > Why the "tasks" is inconvenient? If sysadmin wants to allocte a portion of L3
> > for a pid, the operation in resctl is to write the pid to a "tasks". While
> > in 'procs', the operation is to write a partition to a pid. If considering
> > convenience, they are same, right?
> > 
> > A thread uses either default partition (in root dir) or a sub partition (in
> > sub-directory). Sysadmin can control that. Kernel handles race condition.
> > Any issue with that?
> 
> I don't mean writing the 'tasks' file is inconvenient. So to move a process to
> a group, we do:
> 1. get all thread pid of the process
> 2. write every pid to 'tasks'
> 
> this is inconvenient. And if a new thread is created between 1 and 2, we don't
> put the thread to the group. Am I missing anything?

As said in this doc, "New tasks created by fork(2) and clone(2) are added
to the same group as their parent.". So the new thread created b/w 1 and 2
will automatically go to the "tasks" as the process. Later sysadming can
still move any pid to any group.

Is this convenient?

Thanks.

-Fenghua

Thread

[PATCH v2 00/33] Enable Intel Resource Allocation in Resource Director Technology  "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:00 +0200
  [PATCH v2 32/33] MAINTAINERS: Add maintainer for Intel RDT resource allocation "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:00 +0200
  [PATCH v2 30/33] x86/intel_rdt_rdtgroup.c: Process schemata input from resctrl interface "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:00 +0200
    Re: [PATCH v2 30/33] x86/intel_rdt_rdtgroup.c: Process schemata  input from resctrl interface Thomas Gleixner <tglx@linutronix.de> - 2016-09-09 00:30 +0200
  [PATCH v2 31/33] Documentation/kernel-parameters: Add kernel parameter "resctrl" for CAT "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:00 +0200
    Re: [PATCH v2 31/33] Documentation/kernel-parameters: Add kernel  parameter "resctrl" for CAT Thomas Gleixner <tglx@linutronix.de> - 2016-09-09 00:30 +0200
  [PATCH v2 28/33] x86/intel_rdt_rdtgroup.c: Read and write cpus "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 28/33] x86/intel_rdt_rdtgroup.c: Read and write cpus Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 22:30 +0200
  [PATCH v2 24/33] x86/intel_rdt_rdtgroup.c: Create info directory "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 24/33] x86/intel_rdt_rdtgroup.c: Create info  directory Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 18:10 +0200
  [PATCH v2 11/33] x86/intel_rdt: Hot cpu support for Cache Allocation "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 11/33] x86/intel_rdt: Hot cpu support for Cache  Allocation Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 12:10 +0200
    Re: [PATCH v2 11/33] x86/intel_rdt: Hot cpu support for Cache Allocation Nilay Vaish <nilayvaish@gmail.com> - 2016-09-13 20:20 +0200
      RE: [PATCH v2 11/33] x86/intel_rdt: Hot cpu support for Cache  Allocation "Luck, Tony" <tony.luck@intel.com> - 2016-09-13 21:20 +0200
  [PATCH v2 13/33] Define CONFIG_INTEL_RDT "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 13/33] Define CONFIG_INTEL_RDT Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 12:20 +0200
  [PATCH v2 08/33] x86/intel_rdt: Add Class of service management "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 08/33] x86/intel_rdt: Add Class of service  management Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 11:00 +0200
    Re: [PATCH v2 08/33] x86/intel_rdt: Add Class of service management Nilay Vaish <nilayvaish@gmail.com> - 2016-09-12 18:10 +0200
  [PATCH v2 22/33] x86/intel_rdt.c: Extend RDT to per cache and per resources "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 22/33] x86/intel_rdt.c: Extend RDT to per cache and  per resources Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 17:10 +0200
    Re: [PATCH v2 22/33] x86/intel_rdt.c: Extend RDT to per cache and per  resources Dave Hansen <dave.hansen@intel.com> - 2016-09-14 01:00 +0200
  [PATCH v2 20/33] x86/intel_rdt.h: Header for inter_rdt.c "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 20/33] x86/intel_rdt.h: Header for inter_rdt.c Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 14:40 +0200
  [PATCH v2 10/33] x86/intel_rdt: Implement scheduling support for Intel RDT "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 10/33] x86/intel_rdt: Implement scheduling support  for Intel RDT Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 12:00 +0200
      RE: [PATCH v2 10/33] x86/intel_rdt: Implement scheduling support  for Intel RDT "Yu, Fenghua" <fenghua.yu@intel.com> - 2016-09-15 23:40 +0200
        RE: [PATCH v2 10/33] x86/intel_rdt: Implement scheduling support  for Intel RDT "Luck, Tony" <tony.luck@intel.com> - 2016-09-15 23:50 +0200
    Re: [PATCH v2 10/33] x86/intel_rdt: Implement scheduling support for  Intel RDT Nilay Vaish <nilayvaish@gmail.com> - 2016-09-13 20:00 +0200
  [PATCH v2 16/33] x86/intel_rdt: Class of service and capacity bitmask management for CDP "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 16/33] x86/intel_rdt: Class of service and capacity  bitmask management for CDP Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 12:40 +0200
  [PATCH v2 04/33] drivers/base/cacheinfo.c: Export some cacheinfo functions for others to use "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 04/33] drivers/base/cacheinfo.c: Export some cacheinfo  functions for others to use Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 10:30 +0200
  [PATCH v2 25/33] include/linux/resctrl.h: Define fork and exit functions in a new header file "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 25/33] include/linux/resctrl.h: Define fork and exit  functions in a new header file Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 18:20 +0200
  [PATCH v2 27/33] x86/intel_rdt_rdtgroup.c: Implement resctrl file system commands "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 27/33] x86/intel_rdt_rdtgroup.c: Implement resctrl  file system commands Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 22:20 +0200
    Re: [PATCH v2 27/33] x86/intel_rdt_rdtgroup.c: Implement resctrl  file system commands Fenghua Yu <fenghua.yu@intel.com> - 2016-09-09 00:30 +0200
  [PATCH v2 29/33] x86/intel_rdt_rdtgroup.c: Tasks iterator and write "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 29/33] x86/intel_rdt_rdtgroup.c: Tasks iterator and  write Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 23:00 +0200
  [PATCH v2 17/33] x86/intel_rdt: Hot cpu update for code data prioritization "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 17/33] x86/intel_rdt: Hot cpu update for code data  prioritization Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 12:40 +0200
  [PATCH v2 06/33] Documentation, x86: Documentation for Intel resource allocation user interface "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 06/33] Documentation, x86: Documentation for Intel  resource allocation user interface Borislav Petkov <bp@suse.de> - 2016-09-08 13:30 +0200
    Re: [PATCH v2 06/33] Documentation, x86: Documentation for Intel  resource allocation user interface Fenghua Yu <fenghua.yu@intel.com> - 2016-09-09 00:20 +0200
      Re: [PATCH v2 06/33] Documentation, x86: Documentation for Intel  resource allocation user interface Fenghua Yu <fenghua.yu@intel.com> - 2016-09-09 06:30 +0200
        RE: [PATCH v2 06/33] Documentation, x86: Documentation for Intel  resource allocation user interface "Luck, Tony" <tony.luck@intel.com> - 2016-09-09 20:10 +0200
          RE: [PATCH v2 06/33] Documentation, x86: Documentation for Intel  resource allocation user interface "Luck, Tony" <tony.luck@intel.com> - 2016-09-10 00:10 +0200
            RE: [PATCH v2 06/33] Documentation, x86: Documentation for Intel  resource allocation user interface "Yu, Fenghua" <fenghua.yu@intel.com> - 2016-09-10 02:40 +0200
              Re: [PATCH v2 06/33] Documentation, x86: Documentation for Intel  resource allocation user interface Thomas Gleixner <tglx@linutronix.de> - 2016-09-13 15:40 +0200
  [PATCH v2 03/33] x86, intel_cacheinfo: Enable cache id in x86 "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
  [PATCH v2 09/33] x86/intel_rdt: Add L3 cache capacity bitmask management "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 09/33] x86/intel_rdt: Add L3 cache capacity bitmask  management Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 11:50 +0200
    Re: [PATCH v2 09/33] x86/intel_rdt: Add L3 cache capacity bitmask management Nilay Vaish <nilayvaish@gmail.com> - 2016-09-12 18:20 +0200
  [PATCH v2 07/33] x86/intel_rdt: Add support for Cache Allocation detection "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 07/33] x86/intel_rdt: Add support for Cache Allocation  detection Borislav Petkov <bp@suse.de> - 2016-09-08 14:00 +0200
      RE: [PATCH v2 07/33] x86/intel_rdt: Add support for Cache  Allocation detection "Yu, Fenghua" <fenghua.yu@intel.com> - 2016-09-08 19:00 +0200
        Re: [PATCH v2 07/33] x86/intel_rdt: Add support for Cache Allocation  detection Borislav Petkov <bp@suse.de> - 2016-09-08 19:20 +0200
    Re: [PATCH v2 07/33] x86/intel_rdt: Add support for Cache Allocation  detection Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 15:20 +0200
      RE: [PATCH v2 07/33] x86/intel_rdt: Add support for Cache  Allocation detection "Yu, Fenghua" <fenghua.yu@intel.com> - 2016-09-08 16:00 +0200
    Re: [PATCH v2 07/33] x86/intel_rdt: Add support for Cache Allocation  detection Dave Hansen <dave.hansen@intel.com> - 2016-09-14 00:50 +0200
      Re: [PATCH v2 07/33] x86/intel_rdt: Add support for Cache Allocation  detection "Luck, Tony" <tony.luck@intel.com> - 2016-09-14 01:00 +0200
        Re: [PATCH v2 07/33] x86/intel_rdt: Add support for Cache Allocation  detection Dave Hansen <dave.hansen@intel.com> - 2016-09-14 01:10 +0200
  [PATCH v2 01/33] cacheinfo: Introduce cache id "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 01/33] cacheinfo: Introduce cache id Nilay Vaish <nilayvaish@gmail.com> - 2016-09-09 17:10 +0200
  [PATCH v2 05/33] x86/intel_rdt: Cache Allocation documentation "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
  [PATCH v2 19/33] magic number for resctrl file system "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 19/33] magic number for resctrl file system Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 12:50 +0200
      Re: [PATCH v2 19/33] magic number for resctrl file system Borislav Petkov <bp@alien8.de> - 2016-09-08 12:50 +0200
  [PATCH v2 21/33] x86/intel_rdt_rdtgroup.h: Header for user interface "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 21/33] x86/intel_rdt_rdtgroup.h: Header for user  interface Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 14:50 +0200
  [PATCH v2 26/33] Task fork and exit for rdtgroup "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 26/33] Task fork and exit for rdtgroup Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 21:50 +0200
    Re: [PATCH v2 26/33] Task fork and exit for rdtgroup Dave Hansen <dave.hansen@intel.com> - 2016-09-14 01:20 +0200
      Re: [PATCH v2 26/33] Task fork and exit for rdtgroup "Luck, Tony" <tony.luck@intel.com> - 2016-09-14 01:40 +0200
        Re: [PATCH v2 26/33] Task fork and exit for rdtgroup Dave Hansen <dave.hansen@intel.com> - 2016-09-14 16:30 +0200
  [PATCH v2 18/33] sched.h: Add rg_list and rdtgroup in task_struct "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 18/33] sched.h: Add rg_list and rdtgroup in  task_struct Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 12:40 +0200
  [PATCH v2 02/33] Documentation, ABI: Add a document entry for cache id "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 02/33] Documentation, ABI: Add a document entry for  cache id Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 21:40 +0200
      Re: [PATCH v2 02/33] Documentation, ABI: Add a document entry for  cache id Nilay Vaish <nilayvaish@gmail.com> - 2016-09-09 17:20 +0200
  [PATCH v2 12/33] x86/intel_rdt: Intel haswell Cache Allocation enumeration "Fenghua Yu" <fenghua.yu@intel.com> - 2016-09-08 09:10 +0200
    Re: [PATCH v2 12/33] x86/intel_rdt: Intel haswell Cache Allocation  enumeration Thomas Gleixner <tglx@linutronix.de> - 2016-09-08 12:20 +0200

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