resctrltool: command line tool to manage CAT reservations from userspace

Hello,

Reviews, comments and questions are appreciated on this python script, called resctrltool.py, a utility to manage CAT reservations from the command line.

Why: There are two main reasons for writing this tool, they are:

1) The kernel resctrlfs filesystem format is not functional for being maintained in userspace, since its machine dependant (number of bits in cbm mask changes with L3 size) and dependent on the other allocations registered in resctrlfs.

Users want to specify their reservations in bytes, and not care about position of mask for the reservation.

So the tool performs the translation

kbytes, cbm mask to use for
type, ---> each cacheid
cacheid specification

2) Since each application, such as libvirt, would have to reimplement the translation above, i decided to write a command line interface. Support for systemd being written, which uses this tool.

The tarball can be found at http://people.redhat.com/~mtosatti/resctrltool/

USAGE EXAMPLES

$ ./resctrltool.py 
Command: list
=============

list lists the reservations in place
syntax: resctrltool list [--all-tasks] [--pid-to-name] options:
--all-tasks: by default list truncates the list of the tasks for a given reservation, this option disables the truncation --pid-to-name perform pid to name convertion when listing tasks

Command: create
===============

create creates a new reservation
syntax: resctrltool create --name name --size size --type {both,data,cache} [--cache-id=ID]
options:
--name: name of the reservation to be created, directory name on resctrlfs filesystem
--size size: size of reservation in Kbytes
There are two types of reservations: global ones
(which apply to all cacheid's), and local ones (when --cache-id is specified).
The required order for local ones is as follows:
--type {both,data,code} --size size --cache-id id
That is, --cache-id refers to the size and type options which precede it.
The required order for global ones is as follows:

Automatic filling for --cache-id:
---------------------------------
When --cache-id is not specified for all cacheid's in
the system, the not specified ones are set to the default group mask

Conversion of types
-------------------
When the machine supports CDP, and the user specification has type=both, or when the machine does not support CDP, and the user specification has type=code or type=data the following convertions are performed:
-------------------------------------------------------
USER_SPECIFICATION AVAILABLE HW BEHAVIOUR
-------------------------------------------------------
both code/data code/data regions
using same addresses
-------------------------------------------------------
code/data both code+data region with size
equals to codesize+datasize
-------------------------------------------------------

Command: assign
===============

assign pid to reservation name
syntax: resctrltool assign pid name

Command: delete
===============

delete deletes a reservation (removes resctrlfs directory), and updates the default reservation
syntax: resctrltool delete name

Command: list-cache-ids
=======================

list-cache-ids lists the cache-id -> socket mapping
syntax: resctrltool list-cache-ids

Command: help
=============

help prints help for a particular command
syntax: resctrltool help command

$ ./resctrltool.py  list
=============================
Name: default
Cpus: 000000
Tasks: 1,2,3,5,6,8,9,10,11,12,13,14,15,16,17,18,19,20,21,23,24,25,2 ...
CacheID-0: 6144 KiB (40.000000 %) (ff000) (code and data)
CacheID-1: 6144 KiB (40.000000 %) (ff000) (code and data)
=============================
Name: res1
Cpus: 000000
Tasks: 
CacheID-0: 3072 KiB (20.000000 %) (f) (code and data)
CacheID-1: 3072 KiB (20.000000 %) (f) (code and data)
====== additional info =======
free mask for cache-id 0 is ffff0 (total 12288 KiB)
free mask for cache-id 1 is ffff0 (total 12288 KiB)

$ ./resctrltool.py create --type both --size 1mb --name httpd
$ ./resctrltool.py  list 
=============================
Name: default
Cpus: 000000
Tasks: 1,2,3,5,6,8,9,10,11,12,13,14,15,16,17,18,19,20,21,23,24,25,2 ...
CacheID-0: 10752 KiB (70.000000 %) (fffc0) (code and data)
CacheID-1: 10752 KiB (70.000000 %) (fffc0) (code and data)
=============================
Name: httpd
Cpus: 
Tasks: 
CacheID-0: 1536 KiB (10.000000 %) (30) (code and data)
CacheID-1: 1536 KiB (10.000000 %) (30) (code and data)
=============================
Name: res1
Cpus: 000000
Tasks: 
CacheID-0: 3072 KiB (20.000000 %) (f) (code and data)
CacheID-1: 3072 KiB (20.000000 %) (f) (code and data)
====== additional info =======
free mask for cache-id 0 is fffc0 (total 10752 KiB)
free mask for cache-id 1 is fffc0 (total 10752 KiB)