From 383caddea103eaab7bb495ec446b43748677f749 Mon Sep 17 00:00:00 2001 From: Martin Kletzander Date: Fri, 14 Apr 2023 12:08:59 +0200 Subject: [PATCH] qemu, ch: Move threads to cgroup dir before changing parameters With cgroupv2 this has better effect on the resource allocation. An excerpt from Documentation/admin-guide/cgroup-v2.rst explains is this way: Migrating a process across cgroups is a relatively expensive operation and stateful resources such as memory are not moved together with the process. This is an explicit design decision as there often exist inherent trade-offs between migration and various hot paths in terms of synchronization cost. [...] Setting a non-empty value to "cpuset.mems" causes memory of tasks within the cgroup to be migrated to the designated nodes if they are currently using memory outside of the designated nodes. Signed-off-by: Martin Kletzander Reviewed-by: Michal Privoznik --- src/ch/ch_process.c | 12 ++++++------ src/qemu/qemu_process.c | 10 +++++----- 2 files changed, 11 insertions(+), 11 deletions(-) diff --git a/src/ch/ch_process.c b/src/ch/ch_process.c index c145a78496..44c5b0611e 100644 --- a/src/ch/ch_process.c +++ b/src/ch/ch_process.c @@ -262,6 +262,12 @@ virCHProcessSetupPid(virDomainObj *vm, if (virCgroupNewThread(priv->cgroup, nameval, id, true, &cgroup) < 0) goto cleanup; + /* Move the thread to the sub dir before changing the settings so that + * all take effect even with cgroupv2. */ + VIR_INFO("Adding pid %d to cgroup", pid); + if (virCgroupAddThread(cgroup, pid) < 0) + goto cleanup; + if (virCgroupHasController(priv->cgroup, VIR_CGROUP_CONTROLLER_CPUSET)) { if (use_cpumask && virDomainCgroupSetupCpusetCpus(cgroup, use_cpumask) < 0) @@ -274,12 +280,6 @@ virCHProcessSetupPid(virDomainObj *vm, if (virDomainCgroupSetupVcpuBW(cgroup, period, quota) < 0) goto cleanup; - - /* Move the thread to the sub dir */ - VIR_INFO("Adding pid %d to cgroup", pid); - if (virCgroupAddThread(cgroup, pid) < 0) - goto cleanup; - } if (!affinity_cpumask) diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index b9e9a7d320..8baa882875 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -2630,6 +2630,11 @@ qemuProcessSetupPid(virDomainObj *vm, if (virCgroupNewThread(priv->cgroup, nameval, id, true, &cgroup) < 0) goto cleanup; + /* Move the thread to the sub dir before changing the settings so that + * all take effect even with cgroupv2. */ + if (virCgroupAddThread(cgroup, pid) < 0) + goto cleanup; + if (virCgroupHasController(priv->cgroup, VIR_CGROUP_CONTROLLER_CPUSET)) { if (use_cpumask && virDomainCgroupSetupCpusetCpus(cgroup, use_cpumask) < 0) @@ -2642,11 +2647,6 @@ qemuProcessSetupPid(virDomainObj *vm, if (virDomainCgroupSetupVcpuBW(cgroup, period, quota) < 0) goto cleanup; - - /* Move the thread to the sub dir */ - if (virCgroupAddThread(cgroup, pid) < 0) - goto cleanup; - } if (!affinity_cpumask) -- 2.47.2