The 'nx_huge_pages' option, will force any executable page mapping to be
performed at 4KiB granularity and requires any existing overlapping
huge-page mapping to be also split in 4KiB chunks[1]. This is due to a HW
bug that doesn't affect our NFV use-cases.
The way a huge-page mapping is dropped is by simply deleting the EPT
entry and flushing TLB caches on all affected CPUs. Next vCPU access to
that address will trigger an EPT_VIOLATION, which will jump into the
host for it to handle the page-fault. In our specific case, this means
all isolated CPUs running oslat will hit an EPT_VIOLATION almost exactly
at the same time. Which is bad enough already, but, given our systems
might have a huge number of isolated CPUs, will also create a lot of
contention over the KVM MMU lock. This has been observed to trigger
~100us latency spikes while testing with oslat.
So let's disable the 'kvm.nx_huge_pages' module option.
[1] see kernel commit b7e8c8303ff28
Resolves: rhbz#1976825
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
It updates the KVM modprobe file if its content differs from what's
supported on the current system. It may look a bit over-engineered, but
it's done this way to lower the possibility of race condition.
Resolves: rhbz#1649408
Signed-off-by: Jaroslav Škarvada <jskarvad@redhat.com>
Disabling the ksm and ksmtuned services during boot seems to cause
problems, so do it only once when the profile is first applied and
reenable the services only when full rollback is required.
Resolves: rhbz#1622239
Signed-off-by: Ondřej Lysoněk <olysonek@redhat.com>
KSM disable code is reimplementing systemctl mask command.
Note only that, but it seems a race is possible where the ksm
services may be starting at the same time as disable_ksm()
is running. I believe the mask command should fix that.
There's an important difference in this new version: we don't
try to start KSM when switching away from the cpu-partitioning
profile. This means KSM will probably remain disabled until
the next reboot.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Helper state file for cpu-partitioning script was moved to /run/tuned.
Code for flags manipulation has been simplified.
The /run/tuned directory is explicitly cleared upon uninstallation
of Tuned to get rid of all leftovers / helper files before the reboot.
Added STORAGE_PERSISTENT variable pointing to /var/lib/tuned into
functions to be consistent.
Related: rhbz#1497182
Signed-off-by: Jaroslav Škarvada <jskarvad@redhat.com>
KSM is enabled by default when the qemu-kvm-common-rhev package is
installed. We don't want KSM to run in KVM-RT nor cpu-partitioning
hosts, as it can cause spikes or packet drops.
This series disables KSM in those profiles when they are activated.
Likewise, we re-enable KSM when the profile is de-activated in
case it's enabled by default in systemd.
Luiz Capitulino (3):
profiles: functions: add functions to disable/enable KSM
realtime-virtual-host: disable KSM
cpu-partitioning: disable KSM
profiles/cpu-partitioning/script.sh | 2 ++
profiles/functions | 37 ++++++++++++++++++++++++++++++++
profiles/realtime-virtual-host/script.sh | 3 +++
3 files changed, 42 insertions(+)
--
2.9.5
Return-Path: lcapitulino@redhat.com
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From: Luiz Capitulino <lcapitulino@redhat.com>
To: jskarvad@redhat.com
Cc: kvm-rt@redhat.com
Subject: [PATCH 1/3] profiles: functions: add functions to disable/enable KSM
Date: Tue, 3 Oct 2017 15:53:50 -0400
Message-Id: <20171003195352.22910-2-lcapitulino@redhat.com>
In-Reply-To: <20171003195352.22910-1-lcapitulino@redhat.com>
References: <20171003195352.22910-1-lcapitulino@redhat.com>
X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12
They will be used by the next commits.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
This commit introduces functions to create and delete the
kvm modprobe file used by the realtime profiles.
This is needed because the cpu-partitioning profile wants
the same modprobe file for kvm.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Upon stop action the script is called the following way:
script.sh stop [$HINT]
$HINT is not used if the stop is result of tuned
shutdown. $HINT is set to "profile_switch" if the stop is
result of profile switch.
Signed-off-by: Jaroslav Škarvada <jskarvad@redhat.com>
E.g.:
$ cat /sys/block/sda/queue/scheduler
noop [deadline] cfq
The 'save_sys' function needs to save 'deadline', not 'noop [deadline] cfq'.
Resolves: rhbz#1251507
Signed-off-by: Jaroslav Škarvada <jskarvad@redhat.com>
Added 'verify' shell function to the 'functions' API. This
function is optional, if defined in the script, it is called
during the verification. It's return code is checked. Function
return code '0' means verification passed, other value means
failure.
Signed-off-by: Jaroslav Škarvada <jskarvad@redhat.com>
Some filesystems that are mounted multiple times cannot
be remounted with different options. The error may
confuse users, thus it is better to silence it.
Signed-off-by: Jaroslav Škarvada <jskarvad@redhat.com>
utils: powertop2tuned changed cmdline options and several minor fixes
tuned: removed accidentaly pushed tuned-2.0/profiles/functions
tuned: some minor modifications
