Adjust documentation and behaviour of cpuset

1. Detail the caveats and specific situations and ref the documentation
which will provide more details.

2. Always install the configs, but use /etc/default/ceph-osd-cpuset to
control if the script does anything or not (so, the "osd" cset set is
always active just not set in a special way.
This commit is contained in:
Joshua Boniface 2021-09-29 20:48:40 -04:00
parent 81cf341c32
commit 5797535997
4 changed files with 29 additions and 38 deletions

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@ -147,40 +147,30 @@ pvc_sriov_enable: False
# CPU pinning configuration via cset # CPU pinning configuration via cset
# > ADVANCED TUNING: For most users, this is unnecessary and PVC will run fine with the default scheduling. # > ADVANCED TUNING: For most users, this is unnecessary and PVC will run fine with the default scheduling.
# > These options can be set to maximize the CPU performance of the Ceph subsystem. Because Ceph OSD # Uncomment these options only for testing or if you are certain you meet the following conditions.
# performance is heavily limited more by CPU than anything else, for users with a lot of relatively slow CPU # > These options will tune cpuset (installed by default) to limit Ceph OSDs to certain CPU cores, while
# cores, or for those looking to get maximum storage performance, tuning the pinning options here might # simultaneously limiting other system tasks and VMs to the remaining CPU cores. In effect it dedicates the
# provide noticeable benefits. # specified CPU cores to Ceph OSDs only to ensure those processes can have dedicated CPU time.
# > This configuration makes use of the cset command and will dedicate a specific number of CPU cores to the # > Generally speaking, except in cases where extremely high random read throughput is required and in which
# Ceph OSD processes on each node. This is accomplished by using cset's shield mechanism to create a cgroup # the node(s) have a very large number of physical cores, this setting will not improve performance, and
# which will contain only Ceph OSD processes, while putting everything else onto the remaining CPUs. # may in fact hurt performance. For more details please see the documentation.
# > Avoid using this tuning if you have less than 8 total CPU cores (excluding SMT threads). Otherwise, you # > For optimal performance when using this setting, you should dedicate exactly 2 cores, and their
# might not have enough CPU cores to properly run VMs, unless you are very careful with vCPU allocation. # respective SMT threads if applicable, to each OSD. For instance, with 2 OSDs, 4 real cores (and their
# > Like the 'pvc_nodes' dictionary, these options are set per-host, even if all hosts are identical. This # corresponding SMT threads if applicable) should be specified. More cores has been seen to, in some cases
# is required to handle sitations where hosts might have different CPU topologies. Each host can have a # drop performance further. For more details please see the documentation.
# specific set of CPUs that are included in the shield. # > Use the 'virsh capabilities' command to confim the exact CPU IDs (and SMT "siblings") for these lists.
# > Ensure that you know which CPU cores are "real" and which are SMT "threads". This can be obtained using
# the 'virsh capabilities' command and noting the 'siblings' entries for each CPU.
# > Ensure you consider NUMA nodes when setting up this tuning. Generally speaking it is better to keep the
# OSD processes onto one NUMA node for simplicity; more advanced tuning is outside of the scope of this
# playbook.
# > You should set a number of cores in the shield (along with their respective SMT threads) equal to the
# number of OSDs in the system. This can be adjusted later as needed. For instance, if you have 2 OSDs per
# node, and each node has a 10-core SMT-capable CPU, you would want to assign cores 0 and 1 (the first two
# real cores) and 10 and 11 (the SMT siblings of those cores in 'virsh capabilities') in the cset.
# #
# The shield mode is disabled by default and a commented out example configuration is shown.
pvc_shield_osds_enable: False pvc_shield_osds_enable: False
#pvc_shield_osds_cset: #pvc_shield_osds_cset:
# # This example host has 2x 6-core SMT-enabled CPUs; we want to use cores 0 (+SMT 12) and 2 (+SMT 14), which are # # This example host has 2x 6-core SMT-enabled CPUs; we want to use cores 0 (+SMT 12) and 2 (+SMT 14), which are
# # both on physical CPU 0, for 2x OSDs. # # both on physical CPU 0, for 1x OSD.
# - hostname: pvchv1 # - hostname: pvchv1
# osd_cset: # osd_cset:
# - 0 # - 0
# - 2 # - 2
# - 12 # - 12
# - 14 # - 14
# # These example hosts have 1x 8-core SMT-enabled CPUs; we want to use cores 0 (+SMT 8) and 1 (+SMT 9) for 2x OSDs. # # These example hosts have 1x 8-core SMT-enabled CPUs; we want to use cores 0 (+SMT 8) and 1 (+SMT 9) for 1x OSD.
# - hostname: pvchv2 # - hostname: pvchv2
# osd_cset: # osd_cset:
# - 0 # - 0

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@ -117,14 +117,6 @@
- ceph-mon@{{ ansible_hostname }} - ceph-mon@{{ ansible_hostname }}
- ceph-mgr@{{ ansible_hostname }} - ceph-mgr@{{ ansible_hostname }}
# This is separate from the block to allow *disabling* of the config without removing it
- name: install ceph-osd-cpuset controller config
template:
src: ceph/ceph-osd-cpuset-enable.j2
dest: /etc/default/ceph-osd-cpuset
when:
- pvc_shield_osds_enable is defined
# System OSD CPU shielding activation # System OSD CPU shielding activation
- block: - block:
- name: install packages - name: install packages
@ -134,6 +126,11 @@
- numactl - numactl
state: latest state: latest
- name: install ceph-osd-cpuset controller config
template:
src: ceph/ceph-osd-cpuset-enable.j2
dest: /etc/default/ceph-osd-cpuset
- name: install ceph-osd-cpuset script - name: install ceph-osd-cpuset script
template: template:
src: ceph/ceph-osd-cpuset.j2 src: ceph/ceph-osd-cpuset.j2
@ -167,12 +164,9 @@
enabled: yes enabled: yes
- debug: - debug:
msg: "NOTICE: cpuset configs have NOT been applied to the running system. This node must be rebooted to apply these changes." msg: "NOTICE: Any cpuset configs have NOT been applied to the running system. This node must be rebooted to apply these changes."
when: systemd_file_cpuset.changed or systemd_file_osd.changed
tags: pvc-ceph-cpuset tags: pvc-ceph-cpuset
when: when:
- pvc_shield_osds_enable is defined - pvc_shield_osds_enable is defined
- pvc_shield_osds_cset is defined
- pvc_shield_osds_cset | selectattr('hostname', 'equalto', inventory_hostname) | list | count > 0
- meta: flush_handlers - meta: flush_handlers

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@ -4,10 +4,16 @@
# This script is designed to prepare the cpusets for use by Ceph OSDs, VMs, and other system resources. # This script is designed to prepare the cpusets for use by Ceph OSDs, VMs, and other system resources.
# Libvirt does not make this easy with any way to globally set its CPUs, so we must do this trickery. # Libvirt does not make this easy with any way to globally set its CPUs, so we must do this trickery.
{% if pvc_shield_osds_cset is defined %}
{% set cset_host = pvc_shield_osds_cset | selectattr('hostname', 'equalto', inventory_hostname) %} {% set cset_host = pvc_shield_osds_cset | selectattr('hostname', 'equalto', inventory_hostname) %}
A_OSD_CPUS=( {{ cset_host[0]['osd_cset'] | join(' ') }} ) A_OSD_CPUS=( {{ cset_host[0]['osd_cset'] | join(' ') }} )
A_SYS_CPUS=() A_SYS_CPUS=()
{% else %}
A_OSD_CPUS=()
A_SYS_CPUS=()
{% endif %}
CPU_INFO="$( lscpu )" CPU_INFO="$( lscpu )"
@ -41,7 +47,9 @@ for i in $( seq 0 $(( ${CPU_COUNT} - 1 )) ); do
fi fi
done done
if [[ $( cat /etc/default/ceph-osd-cpuset ) == "True" ]]; then {% raw %}
if [[ $( cat /etc/default/ceph-osd-cpuset ) == "True" && ${#A_OSD_CPUS[@]} -gt 0 ]]; then
{% endraw %}
# Convert arrays into CSV # Convert arrays into CSV
OSD_MEMS="$( IFS=, ; echo "${A_OSD_MEMS[*]}" )" OSD_MEMS="$( IFS=, ; echo "${A_OSD_MEMS[*]}" )"
OSD_CPUS="$( IFS=, ; echo "${A_OSD_CPUS[*]}" )" OSD_CPUS="$( IFS=, ; echo "${A_OSD_CPUS[*]}" )"

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@ -1,6 +1,5 @@
# PVC Ceph OSD cpuset service unit # PVC Ceph OSD cpuset service unit
# {{ ansible_managed }} # {{ ansible_managed }}
{% set cset_host = pvc_shield_osds_cset | selectattr('hostname', 'equalto', inventory_hostname) %}
[Unit] [Unit]
Description = Ceph OSD cpuset shield creation Description = Ceph OSD cpuset shield creation
Before = ceph-osd@.service libvirtd.service Before = ceph-osd@.service libvirtd.service