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qmemman: when low on memory, do not make a VM go below prefmem

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Now the balance() has two different cases: enough memory and low_on_memory.
In the former, distribute memory proportianally; in the former, dont do this, as this
makes a VM go below prefmem.
This commit is contained in:
Rafal Wojtczuk 2010-09-01 12:40:02 +02:00
parent 80771763cf
commit 10408d61db
1 changed files with 55 additions and 22 deletions
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77
dom0/qmemman/qmemman_algo.py
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@ -64,25 +64,12 @@ def balloon(memsize, domdict):
return request
# REQ_SAFETY_NET_FACTOR is a bit greater that 1. So that if the domain yields a bit less than requested, due
# to e.g. rounding errors, we will not get stuck. The surplus will return to the VM during "balance" call.
def balance(xenfree, domdict):
total_memneeded = 0
total_mem_pref = 0
recalc_mem_used(domdict)
#pass 1: compute the above "total" values
for i in domdict.keys():
if domdict[i].meminfo is None:
continue
need = memneeded(domdict[i])
print 'domain' , i, 'act/pref', domdict[i].memory_actual, prefmem(domdict[i]), 'need=', need
total_memneeded += need
total_mem_pref += prefmem(domdict[i])
totalsum = xenfree - total_memneeded
#pass 2: redistribute "totalsum" of memory between domains, proportionally to prefmem
donors = list()
acceptors = list()
#redistribute positive "totalsum" of memory between domains, proportionally to prefmem
def balance_when_enough_memory(domdict, xenfree, total_mem_pref, totalsum):
donors_rq = list()
acceptors_rq = list()
for i in domdict.keys():
if domdict[i].meminfo is None:
continue
@ -92,10 +79,56 @@ def balance(xenfree, domdict):
#prevent rounding errors
target = int(0.995*target_nonint)
if (target < domdict[i].memory_actual):
donors.append((i, target))
donors_rq.append((i, target))
else:
acceptors.append((i, target))
print 'balance: xenfree=', xenfree, 'requests:', donors + acceptors
return donors + acceptors
acceptors_rq.append((i, target))
print 'balance(enough): xenfree=', xenfree, 'requests:', donors_rq + acceptors_rq
return donors_rq + acceptors_rq
#when not enough mem to make everyone be above prefmem, make donors be at prefmem, and
#redistribute anything left between acceptors
def balance_when_low_on_memory(domdict, xenfree, total_mem_pref_acceptors, donors, acceptors):
donors_rq = list()
acceptors_rq = list()
squeezed_mem = xenfree
for i in donors:
avail = -memneeded(domdict[i])
if avail < 10*1024*1024:
#probably we have already tried making it exactly at prefmem, give up
continue
squeezed_mem -= avail
donors_rq.append((i, prefmem(domdict[i])))
for i in acceptors:
scale = 1.0*prefmem(domdict[i])/total_mem_pref_acceptors
target_nonint = domdict[i].memory_actual + scale*squeezed_mem
acceptors_rq.append((i, int(target_nonint)))
print 'balance(low): xenfree=', xenfree, 'requests:', donors_rq + acceptors_rq
return donors_rq + acceptors_rq
def balance(xenfree, domdict):
total_memneeded = 0
total_mem_pref = 0
total_mem_pref_acceptors = 0
recalc_mem_used(domdict)
donors = list()
acceptors = list()
#pass 1: compute the above "total" values
for i in domdict.keys():
if domdict[i].meminfo is None:
continue
need = memneeded(domdict[i])
print 'domain' , i, 'act/pref', domdict[i].memory_actual, prefmem(domdict[i]), 'need=', need
if need < 0:
donors.append(i)
else:
acceptors.append(i)
total_mem_pref_acceptors += prefmem(domdict[i])
total_memneeded += need
total_mem_pref += prefmem(domdict[i])
totalsum = xenfree - total_memneeded
if totalsum > 0:
return balance_when_enough_memory(domdict, xenfree, total_mem_pref, totalsum)
else:
return balance_when_low_on_memory(domdict, xenfree, total_mem_pref_acceptors, donors, acceptors)