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Performance optimization regarding xenstore access

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Reduce number of xenstore access during checking current domain XID.
This commit is contained in:
Marek Marczykowski-Górecki 2013-11-26 20:16:10 +01:00
parent 59b9e43060
commit 3c99ac1d07
1 changed files with 27 additions and 2 deletions
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29
core-modules/000QubesVm.py
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@ -41,6 +41,8 @@ from qubes.qubes import QubesVmCollection,QubesException,QubesHost,QubesVmLabels
from qubes.qubes import defaults,system_path,vm_files,qubes_max_qid
from qubes.qmemman_client import QMemmanClient
xid_to_name_cache = {}
class QubesVm(object):
"""
A representation of one Qubes VM
@ -496,14 +498,32 @@ class QubesVm(object):
def is_disposablevm(self):
return False
def _xid_to_name(self, xid):
if xid in xid_to_name_cache:
return xid_to_name_cache[xid]
else:
domname = xl_ctx.domid_to_name(xid)
if domname:
xid_to_name_cache[xid] = domname
return domname
def get_xl_dominfo(self):
if dry_run:
return
start_xid = self.xid
domains = xl_ctx.list_domains()
for dominfo in domains:
domname = xl_ctx.domid_to_name(dominfo.domid)
if dominfo.domid == start_xid:
return dominfo
elif dominfo.domid < start_xid:
# the current XID can't lower than one noticed earlier, if VM
# was restarted in the meantime, the next XID will greater
continue
domname = self._xid_to_name(dominfo.domid)
if domname == self.name:
self.xid = dominfo.domid
return dominfo
return None
@ -519,8 +539,13 @@ class QubesVm(object):
except xen.lowlevel.xc.Error:
return None
# If previous XID is still valid, this is the right domain - XID can't
# be reused for another domain until system reboot
if start_xid > 0 and domains[0]['domid'] == start_xid:
return domains[0]
for dominfo in domains:
domname = xl_ctx.domid_to_name(dominfo['domid'])
domname = self._xid_to_name(dominfo['domid'])
if domname == self.name:
return dominfo
return None