+# $Id$
+# $URL$
+
+"""Whole core scheduling
+
+"""
+
+import logger
+import os
+
+class CoreSched:
+ """ Whole-core scheduler
+
+ The main entrypoint is adjustCores(self, slivers) which takes a
+ dictionary of sliver records. The cpu_cores field is pulled from the
+ effective rspec (rec["_rspec"]) for each sliver.
+
+ If cpu_cores > 0 for a sliver, then that sliver will reserve one or
+ more of the cpu_cores on the machine.
+
+ One core is always left unreserved for system slices.
+ """
+
+ def __init__(self):
+ self.cpus = []
+
+ def get_cpus(self):
+ """ return a list of available cpu identifiers: [0,1,2,3...]
+ """
+
+ # the cpus never change, so if it's already been computed then don't
+ # worry about it.
+ if self.cpus!=[]:
+ return self.cpus
+
+ cpuset_cpus = open("/dev/cgroup/cpuset.cpus").readline().strip()
+
+ # cpuset.cpus could be something as arbitrary as:
+ # 0,1,2-3,4,5-6
+ # deal with commas and ranges
+ for part in cpuset_cpus.split(","):
+ cpuRange = part.split("-")
+ if len(cpuRange) == 1:
+ cpuRange = (cpuRange[0], cpuRange[0])
+ for i in range(int(cpuRange[0]), int(cpuRange[1])+1):
+ if not i in self.cpus:
+ self.cpus.append(i)
+
+ return self.cpus
+
+ def get_cgroups (self):
+ """ return a list of cgroups
+ this might change as vservers are instantiated, so always compute
+ it dynamically.
+ """
+ cgroups = []
+ filenames = os.listdir("/dev/cgroup")
+ for filename in filenames:
+ if os.path.isdir(os.path.join("/dev/cgroup", filename)):
+ cgroups.append(filename)
+ return cgroups
+
+ def adjustCores (self, slivers):
+ """ slivers is a dict of {sliver_name: rec}
+ rec is a dict of attributes
+ rec['_rspec'] is the effective rspec
+ """
+
+ logger.log("CoreSched: adjusting cores")
+
+ cpus = self.get_cpus()[:]
+
+ reservations = {}
+
+ for name, rec in slivers.iteritems():
+ rspec = rec["_rspec"]
+ cores = rspec.get("cpu_cores", 0)
+ while (cores>0):
+ # one cpu core reserved for best effort and system slices
+ if len(cpus)<=1:
+ logger.log("CoreSched: ran out of cpu cores while scheduling: " + name)
+ else:
+ cpu = cpus.pop()
+ logger.log("CoreSched: allocating cpu " + str(cpu) + " to slice " + name)
+ reservations[name] = reservations.get(name,[]) + [cpu]
+
+ cores = cores-1
+
+ # the leftovers go to everyone else
+ logger.log("CoreSched: allocating cpus " + str(cpus) + " to _default")
+ reservations["_default"] = cpus[:]
+
+ self.reserveCores(reservations)
+
+ def reserveCores (self, reservations):
+ """ give a set of reservations (dictionary of slicename:cpuid_list),
+ write those reservations to the appropriate cgroup files.
+
+ reservations["_default"] is assumed to be the default reservation
+ for slices that do not reserve cores. It's essentially the leftover
+ cpu cores.
+ """
+
+ default = reservations["_default"]
+
+ # set the default vserver cpuset. this will deal with any vservers
+ # that might be created before the nodemanager has had a chance to
+ # update the cpusets.
+ self.reserveDefault(default)
+
+ for cgroup in self.get_cgroups():
+ cpus = reservations.get(cgroup, default)
+
+ logger.log("CoreSched: reserving " + cgroup + " " + str(cpus))
+
+ file("/dev/cgroup/" + cgroup + "/cpuset.cpus", "w").write( self.listToRange(cpus) + "\n" )
+
+ def reserveDefault (self, cpus):
+ if not os.path.exists("/etc/vservers/.defaults/cgroup"):
+ os.makedirs("/etc/vservers/.defaults/cgroup")
+
+ file("/etc/vservers/.defaults/cgroup/cpuset.cpus", "w").write( self.listToRange(cpus) + "\n" )
+
+ def listToRange (self, list):
+ """ take a list of items [1,2,3,5,...] and return it as a range: "1-3,5"
+ for now, just comma-separate
+ """
+ return ",".join( [str(i) for i in list] )
+
+# a little self-test
+if __name__=="__main__":
+ x = CoreSched()
+
+ print "cpus:", x.listToRange(x.get_cpus())
+ print "cgroups:", ",".join(x.get_cgroups())
+
+ # a quick self-test for ScottLab slices sl_test1 and sl_test2
+ # sl_test1 = 1 core
+ # sl_test2 = 1 core
+
+ rspec_sl_test1 = {"cpu_cores": 1}
+ rec_sl_test1 = {"_rspec": rspec_sl_test1}
+
+ rspec_sl_test2 = {"cpu_cores": 1}
+ rec_sl_test2 = {"_rspec": rspec_sl_test2}
+
+ slivers = {"sl_test1": rec_sl_test1, "sl_test2": rec_sl_test2}
+
+ x.adjustCores(slivers)
+