257 lines
11 KiB
Python
Executable File
257 lines
11 KiB
Python
Executable File
#!/usr/bin/python2
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# -*- coding: utf-8 -*-
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#
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# The Qubes OS Project, http://www.qubes-os.org
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#
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# Copyright (C) 2010 Rafal Wojtczuk <rafal@invisiblethingslab.com>
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# Copyright (C) 2013 Marek Marczykowski <marmarek@invisiblethingslab.com>
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#
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# This program is free software; you can redistribute it and/or
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# modify it under the terms of the GNU General Public License
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# as published by the Free Software Foundation; either version 2
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# of the License, or (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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#
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#
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import string
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# This are only defaults - can be overriden by QMemmanServer with values from
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# config file
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CACHE_FACTOR = 1.3
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MIN_PREFMEM = 200*1024*1024
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DOM0_MEM_BOOST = 350*1024*1024
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#untrusted meminfo size is taken from xenstore key, thus its size is limited
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#so splits do not require excessive memory
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def parse_meminfo(untrusted_meminfo):
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untrusted_dict = {}
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#split meminfo contents into lines
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untrusted_lines = string.split(untrusted_meminfo,"\n")
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for untrusted_lines_iterator in untrusted_lines:
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#split a single meminfo line into words
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untrusted_words = string.split(untrusted_lines_iterator)
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if len(untrusted_words) >= 2:
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untrusted_dict[string.rstrip(untrusted_words[0], ":")] = untrusted_words[1]
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return untrusted_dict
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def is_meminfo_suspicious(domain, untrusted_meminfo):
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ret = False
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#check whether the required keys exist and are not negative
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try:
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for i in ('MemTotal', 'MemFree', 'Buffers', 'Cached', 'SwapTotal', 'SwapFree'):
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val = int(untrusted_meminfo[i])*1024
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if (val < 0):
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ret = True
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untrusted_meminfo[i] = val
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except:
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ret = True
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if not ret and untrusted_meminfo['SwapTotal'] < untrusted_meminfo['SwapFree']:
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ret = True
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if not ret and untrusted_meminfo['MemTotal'] < untrusted_meminfo['MemFree'] + untrusted_meminfo['Cached'] + untrusted_meminfo['Buffers']:
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ret = True
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#we could also impose some limits on all the above values
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#but it has little purpose - all the domain can gain by passing e.g.
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#very large SwapTotal is that it will be assigned all free Xen memory
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#it can be achieved with legal values, too, and it will not allow to
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#starve existing domains, by design
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if ret:
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print 'suspicious meminfo for domain', domain.id, 'mem actual', domain.memory_actual, untrusted_meminfo
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return ret
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#called when a domain updates its 'meminfo' xenstore key
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def refresh_meminfo_for_domain(domain, untrusted_xenstore_key):
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untrusted_meminfo = parse_meminfo(untrusted_xenstore_key)
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if untrusted_meminfo is None:
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domain.meminfo = None
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return
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#sanitize start
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if is_meminfo_suspicious(domain, untrusted_meminfo):
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#sanitize end
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domain.meminfo = None
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domain.mem_used = None
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else:
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#sanitized, can assign
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domain.meminfo = untrusted_meminfo
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domain.mem_used = domain.meminfo['MemTotal'] - domain.meminfo['MemFree'] - domain.meminfo['Cached'] - domain.meminfo['Buffers'] + domain.meminfo['SwapTotal'] - domain.meminfo['SwapFree']
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def prefmem(domain):
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#dom0 is special, as it must have large cache, for vbds. Thus, give it a special boost
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if domain.id == '0':
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return min(domain.mem_used*CACHE_FACTOR + 350*1024*1024, domain.memory_maximum)
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return max(min(domain.mem_used*CACHE_FACTOR, domain.memory_maximum), MIN_PREFMEM)
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def memory_needed(domain):
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#do not change
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#in balance(), "distribute total_available_memory proportionally to mempref" relies on this exact formula
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ret = prefmem(domain) - domain.memory_actual
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return ret
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#prepare list of (domain, memory_target) pairs that need to be passed
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#to "xm memset" equivalent in order to obtain "memsize" of memory
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#return empty list when the request cannot be satisfied
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def balloon(memsize, domain_dictionary):
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REQ_SAFETY_NET_FACTOR = 1.05
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donors = list()
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request = list()
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available = 0
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for i in domain_dictionary.keys():
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if domain_dictionary[i].meminfo is None:
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continue
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if domain_dictionary[i].no_progress:
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continue
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need = memory_needed(domain_dictionary[i])
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if need < 0:
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print 'balloon: dom' , i, 'has actual memory', domain_dictionary[i].memory_actual
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donors.append((i,-need))
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available-=need
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print 'req=', memsize, 'avail=', available, 'donors', donors
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if available<memsize:
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return ()
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scale = 1.0*memsize/available
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for donors_iter in donors:
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id, mem = donors_iter
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memborrowed = mem*scale*REQ_SAFETY_NET_FACTOR
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print 'borrow' , memborrowed, 'from', id
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memtarget = int(domain_dictionary[id].memory_actual - memborrowed)
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request.append((id, memtarget))
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return request
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# REQ_SAFETY_NET_FACTOR is a bit greater that 1. So that if the domain yields a bit less than requested, due
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# to e.g. rounding errors, we will not get stuck. The surplus will return to the VM during "balance" call.
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#redistribute positive "total_available_memory" of memory between domains, proportionally to prefmem
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def balance_when_enough_memory(domain_dictionary, xen_free_memory, total_mem_pref, total_available_memory):
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print 'balance_when_enough_memory(', xen_free_memory, total_mem_pref, total_available_memory, ')'
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target_memory = {}
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# memory not assigned because of static max
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left_memory = 0
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acceptors_count = 0
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for i in domain_dictionary.keys():
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if domain_dictionary[i].meminfo is None:
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continue
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if domain_dictionary[i].no_progress:
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continue
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#distribute total_available_memory proportionally to mempref
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scale = 1.0*prefmem(domain_dictionary[i])/total_mem_pref
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target_nonint = prefmem(domain_dictionary[i]) + scale*total_available_memory
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#prevent rounding errors
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target = int(0.999*target_nonint)
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#do not try to give more memory than static max
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if target > domain_dictionary[i].memory_maximum:
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left_memory += target-domain_dictionary[i].memory_maximum
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target = domain_dictionary[i].memory_maximum
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else:
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# count domains which can accept more memory
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acceptors_count += 1
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target_memory[i] = target
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# distribute left memory across all acceptors
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while left_memory > 0 and acceptors_count > 0:
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print ' left_memory:', left_memory, 'acceptors_count:', acceptors_count
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new_left_memory = 0
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new_acceptors_count = acceptors_count
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for i in target_memory.keys():
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target = target_memory[i]
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if target < domain_dictionary[i].memory_maximum:
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memory_bonus = int(0.999*(left_memory/acceptors_count))
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if target+memory_bonus >= domain_dictionary[i].memory_maximum:
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new_left_memory += target+memory_bonus - domain_dictionary[i].memory_maximum
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target = domain_dictionary[i].memory_maximum
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new_acceptors_count -= 1
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else:
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target += memory_bonus
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target_memory[i] = target
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left_memory = new_left_memory
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acceptors_count = new_acceptors_count
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# split target_memory dictionary to donors and acceptors
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# this is needed to first get memory from donors and only then give it to acceptors
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donors_rq = list()
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acceptors_rq = list()
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for i in target_memory.keys():
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target = target_memory[i]
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if (target < domain_dictionary[i].memory_actual):
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donors_rq.append((i, target))
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else:
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acceptors_rq.append((i, target))
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# print 'balance(enough): xen_free_memory=', xen_free_memory, 'requests:', donors_rq + acceptors_rq
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return donors_rq + acceptors_rq
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#when not enough mem to make everyone be above prefmem, make donors be at prefmem, and
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#redistribute anything left between acceptors
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def balance_when_low_on_memory(domain_dictionary, xen_free_memory, total_mem_pref_acceptors, donors, acceptors):
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donors_rq = list()
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acceptors_rq = list()
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squeezed_mem = xen_free_memory
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for i in donors:
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avail = -memory_needed(domain_dictionary[i])
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if avail < 10*1024*1024:
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#probably we have already tried making it exactly at prefmem, give up
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continue
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squeezed_mem -= avail
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donors_rq.append((i, prefmem(domain_dictionary[i])))
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#the below can happen if initially xen free memory is below 50M
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if squeezed_mem < 0:
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return donors_rq
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for i in acceptors:
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scale = 1.0*prefmem(domain_dictionary[i])/total_mem_pref_acceptors
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target_nonint = domain_dictionary[i].memory_actual + scale*squeezed_mem
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#do not try to give more memory than static max
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target = min(int(0.999*target_nonint), domain_dictionary[i].memory_maximum)
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acceptors_rq.append((i, target))
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# print 'balance(low): xen_free_memory=', xen_free_memory, 'requests:', donors_rq + acceptors_rq
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return donors_rq + acceptors_rq
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#redistribute memory across domains
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#called when one of domains update its 'meminfo' xenstore key
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#return the list of (domain, memory_target) pairs to be passed to
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#"xm memset" equivalent
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def balance(xen_free_memory, domain_dictionary):
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#sum of all memory requirements - in other words, the difference between
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#memory required to be added to domains (acceptors) to make them be at their
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#preferred memory, and memory that can be taken from domains (donors) that
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#can provide memory. So, it can be negative when plenty of memory.
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total_memory_needed = 0
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#sum of memory preferences of all domains
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total_mem_pref = 0
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#sum of memory preferences of all domains that require more memory
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total_mem_pref_acceptors = 0
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donors = list() # domains that can yield memory
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acceptors = list() # domains that require more memory
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#pass 1: compute the above "total" values
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for i in domain_dictionary.keys():
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if domain_dictionary[i].meminfo is None:
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continue
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if domain_dictionary[i].no_progress:
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continue
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need = memory_needed(domain_dictionary[i])
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# print 'domain' , i, 'act/pref', domain_dictionary[i].memory_actual, prefmem(domain_dictionary[i]), 'need=', need
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if need < 0 or domain_dictionary[i].memory_actual >= domain_dictionary[i].memory_maximum:
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donors.append(i)
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else:
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acceptors.append(i)
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total_mem_pref_acceptors += prefmem(domain_dictionary[i])
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total_memory_needed += need
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total_mem_pref += prefmem(domain_dictionary[i])
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total_available_memory = xen_free_memory - total_memory_needed
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if total_available_memory > 0:
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return balance_when_enough_memory(domain_dictionary, xen_free_memory, total_mem_pref, total_available_memory)
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else:
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return balance_when_low_on_memory(domain_dictionary, xen_free_memory, total_mem_pref_acceptors, donors, acceptors)
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