Re: [PATCH] qemu: bulk stats: implement (cpu) tune group.

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On 02/11/2015 09:22 AM, Francesco Romani wrote:
> Management applications, like oVirt, may need to setup cpu quota
> limits to enforce QoS for VMs.
> 
> For this purpose, management applications also need to check how
> VMs are behaving with respect to CPU quota. This data is avaialble
> using the virDomainGetSchedulerParameters API.
> 
> This patch adds a new group to bulk stats API to obtain the same
> information.
> 
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1191428
> ---
>  include/libvirt/libvirt-domain.h |  1 +
>  src/libvirt-domain.c             | 16 ++++++++
>  src/qemu/qemu_driver.c           | 84 ++++++++++++++++++++++++++++++++++++++++
>  tools/virsh-domain-monitor.c     |  7 ++++
>  4 files changed, 108 insertions(+)
> 

In general looks good... There's a few spelling and spacing nits below
which I could fix up before pushing for you...

You are missing 'virsh.pod' - something easily added as well.

The one question I have is around the switch name (looking for any other
thoughts...)

Should the option be "cpu-tune" instead of "tune-cpu", especially since
the name of the function has "*CpuTune"? Or even 'sched-info' to match
the 'virsh schedinfo $dom' command?  I suppose some day there'd be
'numa-tune' data desired as well, but that's a different issue...

John
> diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h
> index 4dbd7f5..3d8c6af 100644
> --- a/include/libvirt/libvirt-domain.h
> +++ b/include/libvirt/libvirt-domain.h
> @@ -1700,6 +1700,7 @@ typedef enum {
>      VIR_DOMAIN_STATS_VCPU = (1 << 3), /* return domain virtual CPU info */
>      VIR_DOMAIN_STATS_INTERFACE = (1 << 4), /* return domain interfaces info */
>      VIR_DOMAIN_STATS_BLOCK = (1 << 5), /* return domain block info */
> +    VIR_DOMAIN_STATS_TUNE_CPU = (1 << 6), /* return domain CPU tuning info */
>  } virDomainStatsTypes;
>  
>  typedef enum {
> diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
> index 492e90a..a4effa3 100644
> --- a/src/libvirt-domain.c
> +++ b/src/libvirt-domain.c
> @@ -10990,6 +10990,22 @@ virConnectGetDomainCapabilities(virConnectPtr conn,
>   * "block.<num>.physical" - physical size in bytes of the container of the
>   *                          backing image as unsigned long long.
>   *
> + * VIR_DOMAIN_STATS_TUNE_CPU: Return CPU tuning statistics
> + * and usage information.
> + * The typed parameter keys are in this format:
> + * "tune.vcpu.quota" - max allowed bandwith, in microseconds, as

s/bandwith/bandwidth

> + *                     long long integer. -1 means 'infinite'.
> + * "tune.vcpu.period" - timeframe on which the virtual cpu quota is
> + *                      enforced, in microseconds, as unsigned long long.
> + * "tune.emu.quota" - max allowd bandwith for emulator threads,

s/bandwith/bandwidth
s/allowd/allowed

> + *                    in microseconds, as long long integer.
> + *                    -1 means 'infinite'.
> + * "tune.emu.period" - timeframe on which the emulator quota is
> + *                     enforced, in microseconds, as unsigned long long.
> + * "tune.cpu.shares" - weight of this VM. This value is meaningful
> + *                     only if compared with the other values of
> + *                     the running vms. Expressed as unsigned long long.

s/vms/domains

FWIW: I guess I find it hard to read 'vms' without thinking about the
VMS (or OpenVMS) operating system ;-) [guess where I started my career].

> + *
>   * Note that entire stats groups or individual stat fields may be missing from
>   * the output in case they are not supported by the given hypervisor, are not
>   * applicable for the current state of the guest domain, or their retrieval
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 26fc6a2..5548626 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -18797,6 +18797,89 @@ qemuDomainGetStatsBlock(virQEMUDriverPtr driver,
>  
>  #undef QEMU_ADD_COUNT_PARAM
>  
> +
> +#define QEMU_ADD_PARAM_LL(record, maxparams, name, value) \
> +do { \
> +    if (virTypedParamsAddLLong(&(record)->params, \
> +                               &(record)->nparams, \
> +                               maxparams, \
> +                               name, \
> +                               value) < 0) \
> +        goto cleanup; \
> +} while (0)
> +
> +#define QEMU_ADD_PARAM_ULL(record, maxparams, name, value) \
> +do { \
> +    if (virTypedParamsAddULLong(&(record)->params, \
> +                                &(record)->nparams, \
> +                                maxparams, \
> +                                name, \
> +                                value) < 0) \
> +        goto cleanup; \
> +} while (0)
> +
> +static int
> +qemuDomainGetStatsCpuTune(virQEMUDriverPtr driver,
> +                          virDomainObjPtr dom,
> +                          virDomainStatsRecordPtr record,
> +                          int *maxparams,
> +                          unsigned int privflags ATTRIBUTE_UNUSED)
> +{
> +    int ret = -1;
> +    unsigned long long shares = 0;
> +    qemuDomainObjPrivatePtr priv = dom->privateData;
> +    virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
> +
> +    if (!cfg->privileged ||
> +       !virCgroupHasController(priv->cgroup, VIR_CGROUP_CONTROLLER_CPU)) {
          ^
Just a minor nit about spacing - needs one more...

> +        ret = 0;
> +        goto cleanup;
> +    }
> +
> +    if (virCgroupGetCpuShares(priv->cgroup, &shares) < 0) {
> +        ret = 0;
> +        goto cleanup;
> +    }
> +
> +    QEMU_ADD_PARAM_ULL(record, maxparams, "tune.cpu.shares", shares);
> +
> +    if (virCgroupSupportsCpuBW(priv->cgroup)) {
> +        unsigned long long period = 0;
> +        long long quota = 0;
> +        unsigned long long emulator_period = 0;
> +        long long emulator_quota = 0;
> +        int err;
> +
> +        err = qemuGetVcpusBWLive(dom, &period, &quota);
> +        if (!err) {
> +            QEMU_ADD_PARAM_ULL(record, maxparams,
> +                               "tune.vcpu.period", period);
> +            QEMU_ADD_PARAM_LL(record, maxparams,
> +                              "tune.vcpu.quota", quota);
> +        }
> +
> +        err = qemuGetEmulatorBandwidthLive(dom, priv->cgroup,
> +                                           &emulator_period, &emulator_quota);
> +        if (!err) {
> +            QEMU_ADD_PARAM_ULL(record, maxparams,
> +                               "tune.emu.period", emulator_period);
> +            QEMU_ADD_PARAM_LL(record, maxparams,
> +                              "tune.emu.quota", emulator_quota);
> +        }

having 'emulator_' specific variables probably isn't necessary, but not
a big deal..

> +    }
> +
> +    ret = 0;
> +
> + cleanup:
> +    virObjectUnref(cfg);
> +    return ret;
> +}
> +
> +#undef QEMU_ADD_PARAM_LL
> +
> +#undef QEMU_ADD_PARAM_ULL
> +
> +
>  typedef int
>  (*qemuDomainGetStatsFunc)(virQEMUDriverPtr driver,
>                            virDomainObjPtr dom,
> @@ -18817,6 +18900,7 @@ static struct qemuDomainGetStatsWorker qemuDomainGetStatsWorkers[] = {
>      { qemuDomainGetStatsVcpu, VIR_DOMAIN_STATS_VCPU, false },
>      { qemuDomainGetStatsInterface, VIR_DOMAIN_STATS_INTERFACE, false },
>      { qemuDomainGetStatsBlock, VIR_DOMAIN_STATS_BLOCK, true },
> +    { qemuDomainGetStatsCpuTune, VIR_DOMAIN_STATS_TUNE_CPU, false },
>      { NULL, 0, false }
>  };
>  
> diff --git a/tools/virsh-domain-monitor.c b/tools/virsh-domain-monitor.c
> index 925eb1b..e425e43 100644
> --- a/tools/virsh-domain-monitor.c
> +++ b/tools/virsh-domain-monitor.c
> @@ -1997,6 +1997,10 @@ static const vshCmdOptDef opts_domstats[] = {
>       .type = VSH_OT_BOOL,
>       .help = N_("report domain block device statistics"),
>      },
> +    {.name = "tune-cpu",
> +     .type = VSH_OT_BOOL,
> +     .help = N_("report domain cpu scheduler parameters"),
> +    },
>      {.name = "list-active",
>       .type = VSH_OT_BOOL,
>       .help = N_("list only active domains"),
> @@ -2107,6 +2111,9 @@ cmdDomstats(vshControl *ctl, const vshCmd *cmd)
>      if (vshCommandOptBool(cmd, "block"))
>          stats |= VIR_DOMAIN_STATS_BLOCK;
>  
> +    if (vshCommandOptBool(cmd, "tune-cpu"))
> +        stats |= VIR_DOMAIN_STATS_TUNE_CPU;
> +
>      if (vshCommandOptBool(cmd, "list-active"))
>          flags |= VIR_CONNECT_GET_ALL_DOMAINS_STATS_ACTIVE;
>  
> 

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