Merge branch 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 cache quality monitoring update from Thomas Gleixner:
 "This update provides a complete rewrite of the Cache Quality
  Monitoring (CQM) facility.

  The existing CQM support was duct taped into perf with a lot of issues
  and the attempts to fix those turned out to be incomplete and
  horrible.

  After lengthy discussions it was decided to integrate the CQM support
  into the Resource Director Technology (RDT) facility, which is the
  obvious choise as in hardware CQM is part of RDT. This allowed to add
  Memory Bandwidth Monitoring support on top.

  As a result the mechanisms for allocating cache/memory bandwidth and
  the corresponding monitoring mechanisms are integrated into a single
  management facility with a consistent user interface"

* 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (37 commits)
  x86/intel_rdt: Turn off most RDT features on Skylake
  x86/intel_rdt: Add command line options for resource director technology
  x86/intel_rdt: Move special case code for Haswell to a quirk function
  x86/intel_rdt: Remove redundant ternary operator on return
  x86/intel_rdt/cqm: Improve limbo list processing
  x86/intel_rdt/mbm: Fix MBM overflow handler during CPU hotplug
  x86/intel_rdt: Modify the intel_pqr_state for better performance
  x86/intel_rdt/cqm: Clear the default RMID during hotcpu
  x86/intel_rdt: Show bitmask of shareable resource with other executing units
  x86/intel_rdt/mbm: Handle counter overflow
  x86/intel_rdt/mbm: Add mbm counter initialization
  x86/intel_rdt/mbm: Basic counting of MBM events (total and local)
  x86/intel_rdt/cqm: Add CPU hotplug support
  x86/intel_rdt/cqm: Add sched_in support
  x86/intel_rdt: Introduce rdt_enable_key for scheduling
  x86/intel_rdt/cqm: Add mount,umount support
  x86/intel_rdt/cqm: Add rmdir support
  x86/intel_rdt: Separate the ctrl bits from rmdir
  x86/intel_rdt/cqm: Add mon_data
  x86/intel_rdt: Prepare for RDT monitor data support
  ...

1 files changed, 285 insertions, 38 deletions

diff --git a/Documentation/x86/intel_rdt_ui.txt b/Documentation/x86/intel_rdt_ui.txt
index c491a1b82de2..4d8848e4e224 100644
--- a/Documentation/x86/intel_rdt_ui.txt
+++ b/Documentation/x86/intel_rdt_ui.txt
@@ -6,8 +6,8 @@ Fenghua Yu <fenghua.yu@intel.com>
 Tony Luck <tony.luck@intel.com>
 Vikas Shivappa <vikas.shivappa@intel.com>
 
-This feature is enabled by the CONFIG_INTEL_RDT_A Kconfig and the
-X86 /proc/cpuinfo flag bits "rdt", "cat_l3" and "cdp_l3".
+This feature is enabled by the CONFIG_INTEL_RDT Kconfig and the
+X86 /proc/cpuinfo flag bits "rdt", "cqm", "cat_l3" and "cdp_l3".
 
 To use the feature mount the file system:
 
@@ -17,6 +17,13 @@ mount options are:
 
 "cdp": Enable code/data prioritization in L3 cache allocations.
 
+RDT features are orthogonal. A particular system may support only
+monitoring, only control, or both monitoring and control.
+
+The mount succeeds if either of allocation or monitoring is present, but
+only those files and directories supported by the system will be created.
+For more details on the behavior of the interface during monitoring
+and allocation, see the "Resource alloc and monitor groups" section.
 
 Info directory
 --------------
@@ -24,7 +31,12 @@ Info directory
 The 'info' directory contains information about the enabled
 resources. Each resource has its own subdirectory. The subdirectory
 names reflect the resource names.
-Cache resource(L3/L2)  subdirectory contains the following files:
+
+Each subdirectory contains the following files with respect to
+allocation:
+
+Cache resource(L3/L2)  subdirectory contains the following files
+related to allocation:
 
 "num_closids":  	The number of CLOSIDs which are valid for this
 			resource. The kernel uses the smallest number of
@@ -36,7 +48,15 @@ Cache resource(L3/L2)  subdirectory contains the following files:
 "min_cbm_bits": 	The minimum number of consecutive bits which
 			must be set when writing a mask.
 
-Memory bandwitdh(MB) subdirectory contains the following files:
+"shareable_bits":	Bitmask of shareable resource with other executing
+			entities (e.g. I/O). User can use this when
+			setting up exclusive cache partitions. Note that
+			some platforms support devices that have their
+			own settings for cache use which can over-ride
+			these bits.
+
+Memory bandwitdh(MB) subdirectory contains the following files
+with respect to allocation:
 
 "min_bandwidth":	The minimum memory bandwidth percentage which
 			user can request.
@@ -52,48 +72,152 @@ Memory bandwitdh(MB) subdirectory contains the following files:
 			non-linear. This field is purely informational
 			only.
 
-Resource groups
----------------
+If RDT monitoring is available there will be an "L3_MON" directory
+with the following files:
+
+"num_rmids":		The number of RMIDs available. This is the
+			upper bound for how many "CTRL_MON" + "MON"
+			groups can be created.
+
+"mon_features":	Lists the monitoring events if
+			monitoring is enabled for the resource.
+
+"max_threshold_occupancy":
+			Read/write file provides the largest value (in
+			bytes) at which a previously used LLC_occupancy
+			counter can be considered for re-use.
+
+
+Resource alloc and monitor 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)".
+system.  The default group is the root directory which, immediately
+after mounting, owns all the tasks and cpus in the system and can make
+full use of all resources.
+
+On a system with RDT control features additional directories can be
+created in the root directory that specify different amounts of each
+resource (see "schemata" below). The root and these additional top level
+directories are referred to as "CTRL_MON" groups below.
+
+On a system with RDT monitoring the root directory and other top level
+directories contain a directory named "mon_groups" in which additional
+directories can be created to monitor subsets of tasks in the CTRL_MON
+group that is their ancestor. These are called "MON" groups in the rest
+of this document.
+
+Removing a directory will move all tasks and cpus owned by the group it
+represents to the parent. Removing one of the created CTRL_MON groups
+will automatically remove all MON groups below it.
+
+All groups contain the following files:
+
+"tasks":
+	Reading this file shows the list of all tasks that belong to
+	this group. Writing a task id to the file will add a task to the
+	group. If the group is a CTRL_MON group the task is removed from
+	whichever previous CTRL_MON group owned the task and also from
+	any MON group that owned the task. If the group is a MON group,
+	then the task must already belong to the CTRL_MON parent of this
+	group. The task is removed from any previous MON group.
+
+
+"cpus":
+	Reading this file shows a bitmask of the logical CPUs owned by
+	this group. Writing a mask to this file will add and remove
+	CPUs to/from this group. As with the tasks file a hierarchy is
+	maintained where MON groups may only include CPUs owned by the
+	parent CTRL_MON group.
+
 
-There are three files associated with each group:
+"cpus_list":
+	Just like "cpus", only using ranges of CPUs instead of bitmasks.
 
-"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).
 
-"cpus": A bitmask of logical CPUs assigned to this group. Writing
-	a new mask can add/remove CPUs from this group. Added CPUs
-	are removed from their previous group. Removed ones are
-	given to the default (root) group. You cannot remove CPUs
-	from the default group.
+When control is enabled all CTRL_MON groups will also contain:
 
-"cpus_list": One or more CPU ranges of logical CPUs assigned to this
-	     group. Same rules apply like for the "cpus" file.
+"schemata":
+	A list of all the resources available to this group.
+	Each resource has its own line and format - see below for details.
 
-"schemata": A list of all the resources available to this group.
-	Each resource has its own line and format - see below for
-	details.
+When monitoring is enabled all MON groups will also contain:
 
-When a task is running the following rules define which resources
-are available to it:
+"mon_data":
+	This contains a set of files organized by L3 domain and by
+	RDT event. E.g. on a system with two L3 domains there will
+	be subdirectories "mon_L3_00" and "mon_L3_01".	Each of these
+	directories have one file per event (e.g. "llc_occupancy",
+	"mbm_total_bytes", and "mbm_local_bytes"). In a MON group these
+	files provide a read out of the current value of the event for
+	all tasks in the group. In CTRL_MON groups these files provide
+	the sum for all tasks in the CTRL_MON group and all tasks in
+	MON groups. Please see example section for more details on usage.
+
+Resource allocation rules
+-------------------------
+When a task is running the following rules define which resources are
+available to it:
 
 1) If the task is a member of a non-default group, then the schemata
-for that group is used.
+   for that group is used.
 
 2) Else if the task belongs to the default group, but is running on a
-CPU that is assigned to some specific group, then the schemata for
-the CPU's group is used.
+   CPU that is assigned to some specific group, then the schemata for the
+   CPU's group is used.
 
 3) Otherwise the schemata for the default group is used.
 
+Resource monitoring rules
+-------------------------
+1) If a task is a member of a MON group, or non-default CTRL_MON group
+   then RDT events for the task will be reported in that group.
+
+2) If a task is a member of the default CTRL_MON group, but is running
+   on a CPU that is assigned to some specific group, then the RDT events
+   for the task will be reported in that group.
+
+3) Otherwise RDT events for the task will be reported in the root level
+   "mon_data" group.
+
+
+Notes on cache occupancy monitoring and control
+-----------------------------------------------
+When moving a task from one group to another you should remember that
+this only affects *new* cache allocations by the task. E.g. you may have
+a task in a monitor group showing 3 MB of cache occupancy. If you move
+to a new group and immediately check the occupancy of the old and new
+groups you will likely see that the old group is still showing 3 MB and
+the new group zero. When the task accesses locations still in cache from
+before the move, the h/w does not update any counters. On a busy system
+you will likely see the occupancy in the old group go down as cache lines
+are evicted and re-used while the occupancy in the new group rises as
+the task accesses memory and loads into the cache are counted based on
+membership in the new group.
+
+The same applies to cache allocation control. Moving a task to a group
+with a smaller cache partition will not evict any cache lines. The
+process may continue to use them from the old partition.
+
+Hardware uses CLOSid(Class of service ID) and an RMID(Resource monitoring ID)
+to identify a control group and a monitoring group respectively. Each of
+the resource groups are mapped to these IDs based on the kind of group. The
+number of CLOSid and RMID are limited by the hardware and hence the creation of
+a "CTRL_MON" directory may fail if we run out of either CLOSID or RMID
+and creation of "MON" group may fail if we run out of RMIDs.
+
+max_threshold_occupancy - generic concepts
+------------------------------------------
+
+Note that an RMID once freed may not be immediately available for use as
+the RMID is still tagged the cache lines of the previous user of RMID.
+Hence such RMIDs are placed on limbo list and checked back if the cache
+occupancy has gone down. If there is a time when system has a lot of
+limbo RMIDs but which are not ready to be used, user may see an -EBUSY
+during mkdir.
+
+max_threshold_occupancy is a user configurable value to determine the
+occupancy at which an RMID can be freed.
 
 Schemata files - general concepts
 ---------------------------------
@@ -143,22 +267,22 @@ SKUs. Using a high bandwidth and a low bandwidth setting on two threads
 sharing a core will result in both threads being throttled to use the
 low bandwidth.
 
-L3 details (code and data prioritization disabled)
---------------------------------------------------
+L3 schemata file details (code and data prioritization disabled)
+----------------------------------------------------------------
 With CDP disabled the L3 schemata format is:
 
 	L3:<cache_id0>=<cbm>;<cache_id1>=<cbm>;...
 
-L3 details (CDP enabled via mount option to resctrl)
-----------------------------------------------------
+L3 schemata file details (CDP enabled via mount option to resctrl)
+------------------------------------------------------------------
 When CDP is enabled L3 control is split into two separate resources
 so you can specify independent masks for code and data like this:
 
 	L3data:<cache_id0>=<cbm>;<cache_id1>=<cbm>;...
 	L3code:<cache_id0>=<cbm>;<cache_id1>=<cbm>;...
 
-L2 details
-----------
+L2 schemata file details
+------------------------
 L2 cache does not support code and data prioritization, so the
 schemata format is always:
 
@@ -185,6 +309,8 @@ L3CODE:0=fffff;1=fffff;2=fffff;3=fffff
 L3DATA:0=fffff;1=fffff;2=3c0;3=fffff
 L3CODE:0=fffff;1=fffff;2=fffff;3=fffff
 
+Examples for RDT allocation usage:
+
 Example 1
 ---------
 On a two socket machine (one L3 cache per socket) with just four bits
@@ -410,3 +536,124 @@ void main(void)
 	/* code to read and write directory contents */
 	resctrl_release_lock(fd);
 }
+
+Examples for RDT Monitoring along with allocation usage:
+
+Reading monitored data
+----------------------
+Reading an event file (for ex: mon_data/mon_L3_00/llc_occupancy) would
+show the current snapshot of LLC occupancy of the corresponding MON
+group or CTRL_MON group.
+
+
+Example 1 (Monitor CTRL_MON group and subset of tasks in CTRL_MON group)
+---------
+On a two socket machine (one L3 cache per socket) with just four bits
+for cache bit masks
+
+# mount -t resctrl resctrl /sys/fs/resctrl
+# cd /sys/fs/resctrl
+# mkdir p0 p1
+# echo "L3:0=3;1=c" > /sys/fs/resctrl/p0/schemata
+# echo "L3:0=3;1=3" > /sys/fs/resctrl/p1/schemata
+# echo 5678 > p1/tasks
+# echo 5679 > p1/tasks
+
+The default resource group is unmodified, so we have access to all parts
+of all caches (its schemata file reads "L3:0=f;1=f").
+
+Tasks that are under the control of group "p0" may only allocate from the
+"lower" 50% on cache ID 0, and the "upper" 50% of cache ID 1.
+Tasks in group "p1" use the "lower" 50% of cache on both sockets.
+
+Create monitor groups and assign a subset of tasks to each monitor group.
+
+# cd /sys/fs/resctrl/p1/mon_groups
+# mkdir m11 m12
+# echo 5678 > m11/tasks
+# echo 5679 > m12/tasks
+
+fetch data (data shown in bytes)
+
+# cat m11/mon_data/mon_L3_00/llc_occupancy
+16234000
+# cat m11/mon_data/mon_L3_01/llc_occupancy
+14789000
+# cat m12/mon_data/mon_L3_00/llc_occupancy
+16789000
+
+The parent ctrl_mon group shows the aggregated data.
+
+# cat /sys/fs/resctrl/p1/mon_data/mon_l3_00/llc_occupancy
+31234000
+
+Example 2 (Monitor a task from its creation)
+---------
+On a two socket machine (one L3 cache per socket)
+
+# mount -t resctrl resctrl /sys/fs/resctrl
+# cd /sys/fs/resctrl
+# mkdir p0 p1
+
+An RMID is allocated to the group once its created and hence the <cmd>
+below is monitored from its creation.
+
+# echo $$ > /sys/fs/resctrl/p1/tasks
+# <cmd>
+
+Fetch the data
+
+# cat /sys/fs/resctrl/p1/mon_data/mon_l3_00/llc_occupancy
+31789000
+
+Example 3 (Monitor without CAT support or before creating CAT groups)
+---------
+
+Assume a system like HSW has only CQM and no CAT support. In this case
+the resctrl will still mount but cannot create CTRL_MON directories.
+But user can create different MON groups within the root group thereby
+able to monitor all tasks including kernel threads.
+
+This can also be used to profile jobs cache size footprint before being
+able to allocate them to different allocation groups.
+
+# mount -t resctrl resctrl /sys/fs/resctrl
+# cd /sys/fs/resctrl
+# mkdir mon_groups/m01
+# mkdir mon_groups/m02
+
+# echo 3478 > /sys/fs/resctrl/mon_groups/m01/tasks
+# echo 2467 > /sys/fs/resctrl/mon_groups/m02/tasks
+
+Monitor the groups separately and also get per domain data. From the
+below its apparent that the tasks are mostly doing work on
+domain(socket) 0.
+
+# cat /sys/fs/resctrl/mon_groups/m01/mon_L3_00/llc_occupancy
+31234000
+# cat /sys/fs/resctrl/mon_groups/m01/mon_L3_01/llc_occupancy
+34555
+# cat /sys/fs/resctrl/mon_groups/m02/mon_L3_00/llc_occupancy
+31234000
+# cat /sys/fs/resctrl/mon_groups/m02/mon_L3_01/llc_occupancy
+32789
+
+
+Example 4 (Monitor real time tasks)
+-----------------------------------
+
+A single socket system which has real time tasks running on cores 4-7
+and non real time tasks on other cpus. We want to monitor the cache
+occupancy of the real time threads on these cores.
+
+# mount -t resctrl resctrl /sys/fs/resctrl
+# cd /sys/fs/resctrl
+# mkdir p1
+
+Move the cpus 4-7 over to p1
+# echo f0 > p0/cpus
+
+View the llc occupancy snapshot
+
+# cat /sys/fs/resctrl/p1/mon_data/mon_L3_00/llc_occupancy
+11234000