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scheduler: Make IRQ SMP affinity verification respect ignore_missing

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Changing the SMP affinity of some IRQs is not supported. The semantics
of ignore_missing is that unsupported tunings are not treated as
errors during verification. IRQ SMP affinity being unchangeable can be
regarded as an unsupported tuning, so skip verification of these IRQs
when ignore_missing is set.

The code assumes that the IRQ numbers point to the same device/event
throughout the Tuned run time. We might need to break this assumption
in the future (or maybe not; I haven't looked into how IRQ numbers are
allocated). Either way, the assumption is already present in the code
- rollback assumes the same thing.

Resolves: rhbz#1729936

Signed-off-by: Ondřej Lysoněk <olysonek@redhat.com>
This commit is contained in:
Ondřej Lysoněk 2019-11-21 11:19:31 +01:00
parent 4c3d45c259
commit f7ccf6f092
1 changed files with 18 additions and 5 deletions
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23
tuned/plugins/plugin_scheduler.py
View file

@ -45,6 +45,8 @@ class IRQAffinities(object):
def __init__(self):
self.irqs = {}
self.default = None
# IRQs that don't support changing CPU affinity:
self.unchangeable = []
class SchedulerPlugin(base.Plugin):
"""
@ -565,6 +567,8 @@ class SchedulerPlugin(base.Plugin):
log.error("error applying tuning, cannot get information about running processes: %s"
% e)
# Returns 0 on success, -2 if changing the affinity is not
# supported, -1 if some other error occurs.
def _set_irq_affinity(self, irq, affinity, restoring):
try:
affinity_hex = self._cmd.cpulist2hex(affinity)
@ -573,7 +577,7 @@ class SchedulerPlugin(base.Plugin):
filename = "/proc/irq/%s/smp_affinity" % irq
with open(filename, "w") as f:
f.write(affinity_hex)
return True
return 0
except (OSError, IOError) as e:
# EIO is returned by
# kernel/irq/proc.c:write_irq_affinity() if changing
@ -583,10 +587,11 @@ class SchedulerPlugin(base.Plugin):
and not restoring:
log.debug("Setting SMP affinity of IRQ %s is not supported"
% irq)
return -2
else:
log.error("Failed to set SMP affinity of IRQ %s to '%s': %s"
% (irq, affinity_hex, e))
return False
return -1
def _set_default_irq_affinity(self, affinity):
try:
@ -612,8 +617,11 @@ class SchedulerPlugin(base.Plugin):
_affinity = self._get_intersect_affinity(prev_affinity, affinity, affinity)
if set(_affinity) == set(prev_affinity):
continue
if self._set_irq_affinity(irq, _affinity, False):
res = self._set_irq_affinity(irq, _affinity, False)
if res == 0:
irq_original.irqs[irq] = prev_affinity
elif res == -2:
irq_original.unchangeable.append(irq)
# default affinity
prev_affinity_hex = self._cmd.read_file("/proc/irq/default_smp_affinity")
@ -645,10 +653,15 @@ class SchedulerPlugin(base.Plugin):
correct_affinity))
return res
def _verify_all_irq_affinity(self, correct_affinity):
def _verify_all_irq_affinity(self, correct_affinity, ignore_missing):
irq_original = self._storage.get(self._irq_storage_key, None)
irqs = procfs.interrupts()
res = True
for irq in irqs.keys():
if irq in irq_original.unchangeable and ignore_missing:
description = "IRQ %s does not support changing SMP affinity" % irq
log.info(consts.STR_VERIFY_PROFILE_VALUE_MISSING % description)
continue
try:
current_affinity = irqs[irq]["affinity"]
log.debug("Read SMP affinity of IRQ '%s': '%s'"
@ -686,7 +699,7 @@ class SchedulerPlugin(base.Plugin):
return None
# currently only IRQ affinity verification is supported
if verify:
return self._verify_all_irq_affinity(affinity)
return self._verify_all_irq_affinity(affinity, ignore_missing)
elif enabling:
self._set_ps_affinity(affinity)
self._set_all_irq_affinity(affinity)