123 lines
4.4 KiB
Diff
123 lines
4.4 KiB
Diff
From 57e6b86b53010dd2612b0a6a4e04917673062ecf Mon Sep 17 00:00:00 2001
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From: Jan Friesse <jfriesse@redhat.com>
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Date: Mon, 3 May 2021 15:29:04 +0200
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Subject: [PATCH 3/7] main: Add support for cgroup v2
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Support for cgroup v2 is very similar to cgroup v1 just checking (and
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writing) different file.
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Testing this feature is a bit harder than with cgroup v1 so it's
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probably worh noting in this commit message.
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1. Copy some service file (I've used httpd service) and set
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CPUQuota=30% in the [service] section.
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2. Check /sys/fs/cgroup/cgroup.subtree_control - there should be no
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"cpu"
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3. Start modified service
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4. Check /sys/fs/cgroup/cgroup.subtree_control - there should be "cpu"
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5. Start corosync - It should be able to get rt priority
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When move_to_root_cgroup is disabled, behavior differs:
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- If corosync is started before modified service, so
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there is no "cpu" in /sys/fs/cgroup/cgroup.subtree_control
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corosync starts without problem and gets rt priority.
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Starting modified service later will never add "cpu" into
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/sys/fs/cgroup/cgroup.subtree_control (because corosync is holding
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rt priority and it is placed in the non-root cgroup by systemd).
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- When corosync is started after modified service, so "cpu"
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is in /sys/fs/cgroup/cgroup.subtree_control, corosync is not
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able to get RT priority.
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Signed-off-by: Jan Friesse <jfriesse@redhat.com>
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Reviewed-by: Christine Caulfield <ccaulfie@redhat.com>
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---
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exec/main.c | 21 ++++++++++++++++-----
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man/corosync.conf.5 | 14 ++++++++++----
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2 files changed, 26 insertions(+), 9 deletions(-)
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diff --git a/exec/main.c b/exec/main.c
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index aa6d9fbf..65ae5e4f 100644
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--- a/exec/main.c
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+++ b/exec/main.c
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@@ -1173,6 +1173,7 @@ error_close:
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static int corosync_move_to_root_cgroup(void) {
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FILE *f;
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int res = -1;
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+ const char *cgroup_task_fname = NULL;
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/*
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* /sys/fs/cgroup is hardcoded, because most of Linux distributions are now
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@@ -1183,15 +1184,25 @@ static int corosync_move_to_root_cgroup(void) {
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*/
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f = fopen("/sys/fs/cgroup/cpu/cpu.rt_runtime_us", "rt");
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if (f == NULL) {
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- log_printf(LOGSYS_LEVEL_DEBUG, "cpu.rt_runtime_us doesn't exists -> "
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- "system without cgroup or with disabled CONFIG_RT_GROUP_SCHED");
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+ /*
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+ * Try cgroup v2
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+ */
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+ f = fopen("/sys/fs/cgroup/cgroup.procs", "rt");
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+ if (f == NULL) {
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+ log_printf(LOG_DEBUG, "cpu.rt_runtime_us or cgroup.procs doesn't exist -> "
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+ "system without cgroup or with disabled CONFIG_RT_GROUP_SCHED");
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- res = 0;
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- goto exit_res;
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+ res = 0;
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+ goto exit_res;
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+ } else {
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+ cgroup_task_fname = "/sys/fs/cgroup/cgroup.procs";
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+ }
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+ } else {
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+ cgroup_task_fname = "/sys/fs/cgroup/cpu/tasks";
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}
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(void)fclose(f);
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- f = fopen("/sys/fs/cgroup/cpu/tasks", "w");
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+ f = fopen(cgroup_task_fname, "w");
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if (f == NULL) {
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log_printf(LOGSYS_LEVEL_WARNING, "Can't open cgroups tasks file for writing");
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diff --git a/man/corosync.conf.5 b/man/corosync.conf.5
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index 25289ba4..1c9d2ad7 100644
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--- a/man/corosync.conf.5
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+++ b/man/corosync.conf.5
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@@ -1,6 +1,6 @@
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.\"/*
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.\" * Copyright (c) 2005 MontaVista Software, Inc.
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-.\" * Copyright (c) 2006-2020 Red Hat, Inc.
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+.\" * Copyright (c) 2006-2021 Red Hat, Inc.
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.\" *
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.\" * All rights reserved.
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.\" *
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@@ -32,7 +32,7 @@
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.\" * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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.\" * THE POSSIBILITY OF SUCH DAMAGE.
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.\" */
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-.TH COROSYNC_CONF 5 2021-04-09 "corosync Man Page" "Corosync Cluster Engine Programmer's Manual"
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+.TH COROSYNC_CONF 5 2021-05-03 "corosync Man Page" "Corosync Cluster Engine Programmer's Manual"
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.SH NAME
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corosync.conf - corosync executive configuration file
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@@ -800,8 +800,14 @@ meaning maximal / minimal priority (so minimal / maximal nice value).
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.TP
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move_to_root_cgroup
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Should be set to yes (default) if corosync should try to move itself to root
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-cgroup. This feature is available only for systems with cgroups with RT
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-sched enabled (Linux with CONFIG_RT_GROUP_SCHED kernel option).
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+cgroup. This feature is available only for systems with cgroups v1 with RT
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+sched enabled (Linux with CONFIG_RT_GROUP_SCHED kernel option) and cgroups v2.
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+
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+It's worth noting that currently (May 3 2021) cgroup2 doesn’t yet
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+support control of realtime processes and the cpu controller can only be
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+enabled when all RT processes are in the root cgroup. So when move_to_root_cgroup
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+is disabled and systemd is used, it may be impossible to make systemd options
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+like CPUQuota working correctly until corosync is stopped.
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.TP
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allow_knet_handle_fallback
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--
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2.27.0
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