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...@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...@intel.com> > > > Reviewed-by: Tony Luck <tony.l...@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...@intel.com> > > > +Tony Luck <tony.l...@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? Thanks, Shaohua
