Re: [PATCH 13/34] qemu: Move and rename qemuProcessDetectVcpuPIDs to qemuDomainDetectVcpuPids

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On 01/14/2016 11:27 AM, Peter Krempa wrote:
> Future patches will tweak and reuse the function in different places so
> move it separately first.
> ---
>  src/qemu/qemu_domain.c  | 84 +++++++++++++++++++++++++++++++++++++++++++++++++
>  src/qemu/qemu_domain.h  |  2 ++
>  src/qemu/qemu_process.c | 76 ++------------------------------------------
>  3 files changed, 88 insertions(+), 74 deletions(-)
> 

Although essentially code motion - one nit though in the new part...

> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
> index 0fa2dbe..1ea1cd3 100644
> --- a/src/qemu/qemu_domain.c
> +++ b/src/qemu/qemu_domain.c
> @@ -4257,3 +4257,87 @@ qemuDomainGetVcpuPid(virDomainObjPtr vm,
> 
>      return priv->vcpupids[vcpu];
>  }
> +
> +
> +/**
> + * qemuDomainDetectVcpuPIDs:
> + * @driver: qemu driver data
> + * @vm: domain object
> + * @asyncJob: current asynchronous job type
> + *
> + * Updates vCPU trhead ids in the private data of @vm.

s/trhead/thread

John
> + *
> + * Returns 0 on success -1 on error and reports an appropriate error.
> + */
> +int
> +qemuDomainDetectVcpuPids(virQEMUDriverPtr driver,
> +                         virDomainObjPtr vm,
> +                         int asyncJob)
> +{
> +    pid_t *cpupids = NULL;
> +    int ncpupids;
> +    qemuDomainObjPrivatePtr priv = vm->privateData;
> +
> +    /*
> +     * Current QEMU *can* report info about host threads mapped
> +     * to vCPUs, but it is not in a manner we can correctly
> +     * deal with. The TCG CPU emulation does have a separate vCPU
> +     * thread, but it runs every vCPU in that same thread. So it
> +     * is impossible to setup different affinity per thread.
> +     *
> +     * What's more the 'query-cpus' command returns bizarre
> +     * data for the threads. It gives the TCG thread for the
> +     * vCPU 0, but for vCPUs 1-> N, it actually replies with
> +     * the main process thread ID.
> +     *
> +     * The result is that when we try to set affinity for
> +     * vCPU 1, it will actually change the affinity of the
> +     * emulator thread :-( When you try to set affinity for
> +     * vCPUs 2, 3.... it will fail if the affinity was
> +     * different from vCPU 1.
> +     *
> +     * We *could* allow vcpu pinning with TCG, if we made the
> +     * restriction that all vCPUs had the same mask. This would
> +     * at least let us separate emulator from vCPUs threads, as
> +     * we do for KVM. It would need some changes to our cgroups
> +     * CPU layout though, and error reporting for the config
> +     * restrictions.
> +     *
> +     * Just disable CPU pinning with TCG until someone wants
> +     * to try to do this hard work.
> +     */
> +    if (vm->def->virtType == VIR_DOMAIN_VIRT_QEMU) {
> +        priv->nvcpupids = 0;
> +        priv->vcpupids = NULL;
> +        return 0;
> +    }
> +
> +    if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) < 0)
> +        return -1;
> +    ncpupids = qemuMonitorGetCPUInfo(priv->mon, &cpupids);
> +    if (qemuDomainObjExitMonitor(driver, vm) < 0)
> +        return -1;
> +    /* failure to get the VCPU<-> PID mapping or to execute the query
> +     * command will not be treated fatal as some versions of qemu don't
> +     * support this command */
> +    if (ncpupids <= 0) {
> +        virResetLastError();
> +
> +        priv->nvcpupids = 0;
> +        priv->vcpupids = NULL;
> +        return 0;
> +    }
> +
> +    if (ncpupids != virDomainDefGetVcpus(vm->def)) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR,
> +                       _("got wrong number of vCPU pids from QEMU monitor. "
> +                         "got %d, wanted %d"),
> +                       ncpupids, virDomainDefGetVcpus(vm->def));
> +        VIR_FREE(cpupids);
> +        return -1;
> +    }
> +
> +    priv->nvcpupids = ncpupids;
> +    priv->vcpupids = cpupids;
> +    return 0;
> +}
> diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
> index 7fc4fff..6a8cf70 100644
> --- a/src/qemu/qemu_domain.h
> +++ b/src/qemu/qemu_domain.h
> @@ -508,5 +508,7 @@ int qemuDomainDefValidateMemoryHotplug(const virDomainDef *def,
> 
>  bool qemuDomainHasVcpuPids(virDomainObjPtr vm);
>  pid_t qemuDomainGetVcpuPid(virDomainObjPtr vm, unsigned int vcpu);
> +int qemuDomainDetectVcpuPids(virQEMUDriverPtr driver, virDomainObjPtr vm,
> +                             int asyncJob);
> 
>  #endif /* __QEMU_DOMAIN_H__ */
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index dec4572..a7c3094 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -1962,78 +1962,6 @@ qemuProcessWaitForMonitor(virQEMUDriverPtr driver,
>      return ret;
>  }
> 
> -static int
> -qemuProcessDetectVcpuPIDs(virQEMUDriverPtr driver,
> -                          virDomainObjPtr vm, int asyncJob)
> -{
> -    pid_t *cpupids = NULL;
> -    int ncpupids;
> -    qemuDomainObjPrivatePtr priv = vm->privateData;
> -
> -    /*
> -     * Current QEMU *can* report info about host threads mapped
> -     * to vCPUs, but it is not in a manner we can correctly
> -     * deal with. The TCG CPU emulation does have a separate vCPU
> -     * thread, but it runs every vCPU in that same thread. So it
> -     * is impossible to setup different affinity per thread.
> -     *
> -     * What's more the 'query-cpus' command returns bizarre
> -     * data for the threads. It gives the TCG thread for the
> -     * vCPU 0, but for vCPUs 1-> N, it actually replies with
> -     * the main process thread ID.
> -     *
> -     * The result is that when we try to set affinity for
> -     * vCPU 1, it will actually change the affinity of the
> -     * emulator thread :-( When you try to set affinity for
> -     * vCPUs 2, 3.... it will fail if the affinity was
> -     * different from vCPU 1.
> -     *
> -     * We *could* allow vcpu pinning with TCG, if we made the
> -     * restriction that all vCPUs had the same mask. This would
> -     * at least let us separate emulator from vCPUs threads, as
> -     * we do for KVM. It would need some changes to our cgroups
> -     * CPU layout though, and error reporting for the config
> -     * restrictions.
> -     *
> -     * Just disable CPU pinning with TCG until someone wants
> -     * to try to do this hard work.
> -     */
> -    if (vm->def->virtType == VIR_DOMAIN_VIRT_QEMU) {
> -        priv->nvcpupids = 0;
> -        priv->vcpupids = NULL;
> -        return 0;
> -    }
> -
> -    if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) < 0)
> -        return -1;
> -    ncpupids = qemuMonitorGetCPUInfo(priv->mon, &cpupids);
> -    if (qemuDomainObjExitMonitor(driver, vm) < 0)
> -        return -1;
> -    /* failure to get the VCPU<-> PID mapping or to execute the query
> -     * command will not be treated fatal as some versions of qemu don't
> -     * support this command */
> -    if (ncpupids <= 0) {
> -        virResetLastError();
> -
> -        priv->nvcpupids = 0;
> -        priv->vcpupids = NULL;
> -        return 0;
> -    }
> -
> -    if (ncpupids != virDomainDefGetVcpus(vm->def)) {
> -        virReportError(VIR_ERR_INTERNAL_ERROR,
> -                       _("got wrong number of vCPU pids from QEMU monitor. "
> -                         "got %d, wanted %d"),
> -                       ncpupids, virDomainDefGetVcpus(vm->def));
> -        VIR_FREE(cpupids);
> -        return -1;
> -    }
> -
> -    priv->nvcpupids = ncpupids;
> -    priv->vcpupids = cpupids;
> -    return 0;
> -}
> -
> 
>  static int
>  qemuProcessDetectIOThreadPIDs(virQEMUDriverPtr driver,
> @@ -4982,7 +4910,7 @@ qemuProcessLaunch(virConnectPtr conn,
>          goto cleanup;
> 
>      VIR_DEBUG("Detecting VCPU PIDs");
> -    if (qemuProcessDetectVcpuPIDs(driver, vm, asyncJob) < 0)
> +    if (qemuDomainDetectVcpuPids(driver, vm, asyncJob) < 0)
>          goto cleanup;
> 
>      VIR_DEBUG("Detecting IOThread PIDs");
> @@ -5689,7 +5617,7 @@ int qemuProcessAttach(virConnectPtr conn ATTRIBUTE_UNUSED,
>      }
> 
>      VIR_DEBUG("Detecting VCPU PIDs");
> -    if (qemuProcessDetectVcpuPIDs(driver, vm, QEMU_ASYNC_JOB_NONE) < 0)
> +    if (qemuDomainDetectVcpuPids(driver, vm, QEMU_ASYNC_JOB_NONE) < 0)
>          goto error;
> 
>      VIR_DEBUG("Detecting IOThread PIDs");
> 

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