[libvirt] [PATCH] set cpu bandwidth for the vm
Daniel Veillard
veillard at redhat.com
Tue Jul 26 03:25:24 UTC 2011
On Mon, Jul 25, 2011 at 01:37:14PM +0800, Wen Congyang wrote:
> The cpu bandwidth is applied at the vcpu group level. We should apply it
> at the vm group level too, because the vm may do heavy I/O, and it will affect
> the other vm.
>
> We apply cpu bandwidth at the vcpu and the vm group level, so we must ensure
> that max(child_quota) <= parent_quota when we modify cpu bandwidth.
>
> ---
> src/qemu/qemu_cgroup.c | 38 ++++++++++-------
> src/qemu/qemu_driver.c | 103 ++++++++++++++++++++++++++++++++++++-----------
> 2 files changed, 101 insertions(+), 40 deletions(-)
>
> diff --git a/src/qemu/qemu_cgroup.c b/src/qemu/qemu_cgroup.c
> index d6e4cbc..2a10bd2 100644
> --- a/src/qemu/qemu_cgroup.c
> +++ b/src/qemu/qemu_cgroup.c
> @@ -435,6 +435,7 @@ int qemuSetupCgroupForVcpu(struct qemud_driver *driver, virDomainObjPtr vm)
> unsigned int i;
> unsigned long long period = vm->def->cputune.period;
> long long quota = vm->def->cputune.quota;
> + long long vm_quota = 0;
>
> if (driver->cgroup == NULL)
> return 0; /* Not supported, so claim success */
> @@ -447,26 +448,31 @@ int qemuSetupCgroupForVcpu(struct qemud_driver *driver, virDomainObjPtr vm)
> goto cleanup;
> }
>
> + /* Set cpu bandwidth for the vm */
> + if (period || quota) {
> + if (qemuCgroupControllerActive(driver, VIR_CGROUP_CONTROLLER_CPU)) {
> + /* Ensure that we can multiply by vcpus without overflowing. */
> + if (quota > LLONG_MAX / vm->def->vcpus) {
> + virReportSystemError(EINVAL,
> + _("%s"),
> + "Unable to set cpu bandwidth quota");
> + goto cleanup;
> + }
> +
> + if (quota > 0)
> + vm_quota = quota * vm->def->vcpus;
> + else
> + vm_quota = quota;
> + if (qemuSetupCgroupVcpuBW(cgroup, period, vm_quota) < 0)
> + goto cleanup;
> + }
> + }
> +
> if (priv->nvcpupids == 0 || priv->vcpupids[0] == vm->pid) {
> /* If we does not know VCPU<->PID mapping or all vcpu runs in the same
> * thread, we cannot control each vcpu.
> */
> - if (period || quota) {
> - if (qemuCgroupControllerActive(driver, VIR_CGROUP_CONTROLLER_CPU)) {
> - /* Ensure that we can multiply by vcpus without overflowing. */
> - if (quota > LLONG_MAX / vm->def->vcpus) {
> - virReportSystemError(EINVAL,
> - _("%s"),
> - "Unable to set cpu bandwidth quota");
> - goto cleanup;
> - }
> -
> - if (quota > 0)
> - quota *= vm->def->vcpus;
> - if (qemuSetupCgroupVcpuBW(cgroup, period, quota) < 0)
> - goto cleanup;
> - }
> - }
> + virCgroupFree(&cgroup);
> return 0;
> }
>
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 5df58b1..52e5d69 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -6051,43 +6051,98 @@ qemuSetVcpusBWLive(virDomainObjPtr vm, virCgroupPtr cgroup,
> qemuDomainObjPrivatePtr priv = vm->privateData;
> virCgroupPtr cgroup_vcpu = NULL;
> int rc;
> + long long vm_quota = 0;
> + long long old_quota = 0;
> + unsigned long long old_period = 0;
>
> if (period == 0 && quota == 0)
> return 0;
>
> - if (priv->nvcpupids == 0 || priv->vcpupids[0] == vm->pid) {
> - /* If we does not know VCPU<->PID mapping or all vcpu runs in the same
> - * thread, we cannot control each vcpu.
> - */
> - /* Ensure that we can multiply by vcpus without overflowing. */
> - if (quota > LLONG_MAX / vm->def->vcpus) {
> - virReportSystemError(EINVAL,
> - _("%s"),
> - "Unable to set cpu bandwidth quota");
> - goto cleanup;
> - }
> + /* Ensure that we can multiply by vcpus without overflowing. */
> + if (quota > LLONG_MAX / vm->def->vcpus) {
> + virReportSystemError(EINVAL,
> + _("%s"),
> + "Unable to set cpu bandwidth quota");
> + goto cleanup;
> + }
> +
> + if (quota > 0)
> + vm_quota = quota * vm->def->vcpus;
> + else
> + vm_quota = quota;
>
> - if (quota > 0)
> - quota *= vm->def->vcpus;
> - return qemuSetupCgroupVcpuBW(cgroup, period, quota);
> + rc = virCgroupGetCpuCfsQuota(cgroup, &old_quota);
> + if (rc < 0) {
> + virReportSystemError(-rc, "%s",
> + _("unable to get cpu bandwidth tunable"));
> + goto cleanup;
> }
>
> - for (i = 0; i < priv->nvcpupids; i++) {
> - rc = virCgroupForVcpu(cgroup, i, &cgroup_vcpu, 0);
> - if (rc < 0) {
> - virReportSystemError(-rc,
> - _("Unable to find vcpu cgroup for %s(vcpu:"
> - " %d)"),
> - vm->def->name, i);
> - goto cleanup;
> + rc = virCgroupGetCpuCfsPeriod(cgroup, &old_period);
> + if (rc < 0) {
> + virReportSystemError(-rc, "%s",
> + _("unable to get cpu bandwidth period tunable"));
> + goto cleanup;
> + }
> +
> + /*
> + * If quota will be changed to a small value, we should modify vcpu's quota
> + * first. Otherwise, we should modify vm's quota first.
> + *
> + * If period will be changed to a small value, we should modify vm's period
> + * first. Otherwise, we should modify vcpu's period first.
> + *
> + * If both quota and period will be changed to a big/small value, we cannot
> + * modify period and quota together.
> + */
> + if ((quota != 0) && (period != 0)) {
> + if (((quota > old_quota) && (period > old_period)) ||
> + ((quota < old_quota) && (period < old_period))) {
> + /* modify period */
> + if (qemuSetVcpusBWLive(vm, cgroup, period, 0) < 0)
> + goto cleanup;
> +
> + /* modify quota */
> + if (qemuSetVcpusBWLive(vm, cgroup, 0, quota) < 0)
> + goto cleanup;
> + return 0;
> }
> + }
>
> - if (qemuSetupCgroupVcpuBW(cgroup_vcpu, period, quota) < 0)
> + if (((vm_quota != 0) && (vm_quota > old_quota)) ||
> + ((period != 0) && (period < old_period)))
> + /* Set cpu bandwidth for the vm */
> + if (qemuSetupCgroupVcpuBW(cgroup, period, vm_quota) < 0)
> goto cleanup;
>
> - virCgroupFree(&cgroup_vcpu);
> + /* If we does not know VCPU<->PID mapping or all vcpu runs in the same
> + * thread, we cannot control each vcpu. So we only modify cpu bandwidth
> + * when each vcpu has a separated thread.
> + */
> + if (priv->nvcpupids != 0 && priv->vcpupids[0] != vm->pid) {
> + for (i = 0; i < priv->nvcpupids; i++) {
> + rc = virCgroupForVcpu(cgroup, i, &cgroup_vcpu, 0);
> + if (rc < 0) {
> + virReportSystemError(-rc,
> + _("Unable to find vcpu cgroup for %s(vcpu:"
> + " %d)"),
> + vm->def->name, i);
> + goto cleanup;
> + }
> +
> + if (qemuSetupCgroupVcpuBW(cgroup_vcpu, period, quota) < 0)
> + goto cleanup;
> +
> + virCgroupFree(&cgroup_vcpu);
> + }
> }
>
> + if (((vm_quota != 0) && (vm_quota <= old_quota)) ||
> + ((period != 0) && (period >= old_period)))
> + /* Set cpu bandwidth for the vm */
> + if (qemuSetupCgroupVcpuBW(cgroup, period, vm_quota) < 0)
> + goto cleanup;
> +
> return 0;
>
> cleanup:
I looked at it yesterday but while looking correct I was hoping
someone with more interest on that thread would comment/ACK it.
ACK,
I just tagged libvirt-0.9.4-rc1, so that won't make it but it will be
in rc2 and final which is the important point :-)
Daniel
--
Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/
daniel at veillard.com | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library http://libvirt.org/
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