[libvirt] [PATCH 3/3] qemu: Add support for setting vCPU and I/O thread scheduler setting

[John Ferlan]

On 01/13/2015 02:57 AM, Martin Kletzander wrote:
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1178986

Could use a bit more details here.

> 
> Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
> ---
>  src/qemu/qemu_driver.c  |  7 ++++-
>  src/qemu/qemu_process.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++-
>  src/qemu/qemu_process.h |  5 +++-
>  3 files changed, 85 insertions(+), 3 deletions(-)
> 

No change to qemu_hotplug necessary??

> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index cdf4173..fdfd4e9 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -1,7 +1,7 @@
>  /*
>   * qemu_driver.c: core driver methods for managing qemu guests
>   *
> - * Copyright (C) 2006-2014 Red Hat, Inc.
> + * Copyright (C) 2006-2015 Red Hat, Inc.
>   * Copyright (C) 2006 Daniel P. Berrange
>   *
>   * This library is free software; you can redistribute it and/or
> @@ -4491,6 +4491,11 @@ static int qemuDomainHotplugVcpus(virQEMUDriverPtr driver,
>              }
> 
>              virCgroupFree(&cgroup_vcpu);
> +
> +            if (qemuProcessSetSchedParams(i, cpupids[i],
> +                                          vm->def->cputune.nvcpusched,
> +                                          vm->def->cputune.vcpusched) < 0)
> +                goto cleanup;
>          }
>      } else {
>          for (i = oldvcpus - 1; i >= nvcpus; i--) {
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index c18204b..0d69c43 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -1,7 +1,7 @@
>  /*
>   * qemu_process.c: QEMU process management
>   *
> - * Copyright (C) 2006-2014 Red Hat, Inc.
> + * Copyright (C) 2006-2015 Red Hat, Inc.
>   *
>   * This library is free software; you can redistribute it and/or
>   * modify it under the terms of the GNU Lesser General Public
> @@ -2574,6 +2574,76 @@ qemuProcessSetIOThreadsAffinity(virDomainObjPtr vm)
>      return ret;
>  }
> 
> +/* Set Scheduler parameters for vCPU or I/O threads. */
> +int
> +qemuProcessSetSchedParams(int id,
> +                          pid_t pid,
> +                          size_t nsp,
> +                          virDomainThreadSchedParamPtr sp)
> +{
> +    int sched = 0;
> +    size_t i = 0;
> +    virDomainThreadSchedParamPtr s = NULL;
> +
> +    for (i = 0; i < nsp; i++) {
> +        if (id != sp[i].id)
> +            continue;
> +
> +        s = sp + i;
> +        break;
> +    }

Ug. I think this would be easier with the bitmap like cpuset.  I'll wait
for your feedback on 2/3...

Do you plan to add a new command 'vcpusched' (like vcpupin).  It's
something that's desired for IOThreads, so perhaps one of us gets to
reuse code :-)

John
> +
> +    if (!s)
> +        return 0;
> +
> +    switch (s->scheduler) {
> +    case VIR_DOMAIN_THREAD_SCHED_BATCH:
> +        sched = SCHED_BATCH;
> +        break;
> +
> +    case VIR_DOMAIN_THREAD_SCHED_IDLE:
> +        sched = SCHED_IDLE;
> +        break;
> +
> +    case VIR_DOMAIN_THREAD_SCHED_FIFO:
> +        sched = SCHED_FIFO;
> +        break;
> +
> +    case VIR_DOMAIN_THREAD_SCHED_RR:
> +        sched = SCHED_RR;
> +        break;
> +
> +    case VIR_DOMAIN_THREAD_SCHED_OTHER:
> +    case VIR_DOMAIN_THREAD_SCHED_LAST:
> +        return 0;
> +    }
> +
> +    return virProcessSetScheduler(pid, sched, s->priority);
> +}
> +
> +static int
> +qemuProcessSetSchedulers(virDomainObjPtr vm)
> +{
> +    qemuDomainObjPrivatePtr priv = vm->privateData;
> +    size_t i = 0;
> +
> +    for (i = 0; i < vm->def->vcpus; i++) {
> +        if (qemuProcessSetSchedParams(i, priv->vcpupids[i],
> +                                      vm->def->cputune.nvcpusched,
> +                                      vm->def->cputune.vcpusched) < 0)
> +            return -1;
> +    }
> +
> +    for (i = 0; i < vm->def->iothreads; i++) {
> +        if (qemuProcessSetSchedParams(i, priv->iothreadpids[i],
> +                                      vm->def->cputune.niothreadsched,
> +                                      vm->def->cputune.iothreadsched) < 0)
> +            return -1;
> +    }
> +
> +    return 0;
> +}
> +
>  static int
>  qemuProcessInitPasswords(virConnectPtr conn,
>                           virQEMUDriverPtr driver,
> @@ -4750,6 +4820,10 @@ int qemuProcessStart(virConnectPtr conn,
>      if (qemuProcessSetIOThreadsAffinity(vm) < 0)
>          goto cleanup;
> 
> +    VIR_DEBUG("Setting scheduler parameters");
> +    if (qemuProcessSetSchedulers(vm) < 0)
> +        goto cleanup;
> +
>      VIR_DEBUG("Setting any required VM passwords");
>      if (qemuProcessInitPasswords(conn, driver, vm, asyncJob) < 0)
>          goto cleanup;
> diff --git a/src/qemu/qemu_process.h b/src/qemu/qemu_process.h
> index 5948ea4..2e1d393 100644
> --- a/src/qemu/qemu_process.h
> +++ b/src/qemu/qemu_process.h
> @@ -1,7 +1,7 @@
>  /*
>   * qemu_process.h: QEMU process management
>   *
> - * Copyright (C) 2006-2012 Red Hat, Inc.
> + * Copyright (C) 2006-2012, 2015 Red Hat, Inc.
>   *
>   * This library is free software; you can redistribute it and/or
>   * modify it under the terms of the GNU Lesser General Public
> @@ -104,4 +104,7 @@ virBitmapPtr qemuPrepareCpumap(virQEMUDriverPtr driver,
> 
>  int qemuProcessReadLog(int fd, char *buf, int buflen, int off, bool skipchar);
> 
> +int qemuProcessSetSchedParams(int id, pid_t pid, size_t nsp,
> +                              virDomainThreadSchedParamPtr sp);
> +
>  #endif /* __QEMU_PROCESS_H__ */
>