[libvirt] [REPOST PATCH v2 05/12] lib: Introduce virDomainSetIOThreadParams

[Michal Privoznik]

On 11/05/2018 01:58 PM, John Ferlan wrote:
> Create a new API that will allow an adjustment of IOThread
> polling parameters for the specified IOThread. These parameters
> will not be saved in the guest XML. Currently the only parameters
> supported will allow the hypervisor to adjust the parameters used
> to limit and alter the scope of the polling interval. The polling
> interval allows the IOThread to spend more or less time processing
> in the guest.
> 
> Based on code originally posted by Pavel Hrdina <phrdina at redhat.com>
> to add virDomainAddIOThreadParams and virDomainModIOThreadParams.
> Modification of those changes to use virDomainSetIOThreadParams
> instead and remove concepts related to saving the data in guest
> XML as well as the way to specifically enable the polling parameters.
> 
> Signed-off-by: John Ferlan <jferlan at redhat.com>
> ACKed-by: Michal Privoznik <mprivozn at redhat.com>
> ---
>  include/libvirt/libvirt-domain.h | 44 ++++++++++++++++++++
>  src/driver-hypervisor.h          |  8 ++++
>  src/libvirt-domain.c             | 70 ++++++++++++++++++++++++++++++++
>  src/libvirt_public.syms          |  5 +++
>  src/remote/remote_driver.c       |  1 +
>  src/remote/remote_protocol.x     | 21 +++++++++-
>  src/remote_protocol-structs      | 10 +++++
>  7 files changed, 158 insertions(+), 1 deletion(-)
> 
> diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h
> index 58fd4bc10c..bf89d0149f 100644
> --- a/include/libvirt/libvirt-domain.h
> +++ b/include/libvirt/libvirt-domain.h
> @@ -1911,6 +1911,50 @@ int                  virDomainDelIOThread(virDomainPtr domain,
>                                            unsigned int iothread_id,
>                                            unsigned int flags);
>  
> +/* IOThread set parameters */
> +
> +/**
> + * VIR_DOMAIN_IOTHREAD_POLL_MAX_NS:
> + *
> + * The maximum polling time that can be used by polling algorithm in ns.
> + * The polling time starts at 0 (zero) and is the time spent by the guest
> + * to process IOThread data before returning the CPU to the host. The
> + * polling time will be dynamically modified over time based on the
> + * poll_grow and poll_shrink parameters provided. A value set too large
> + * will cause more CPU time to be allocated the guest. A value set too
> + * small will not provide enough cycles for the guest to process data.
> + * The polling interval is not available for statistical purposes.
> + */
> +# define VIR_DOMAIN_IOTHREAD_POLL_MAX_NS "poll_max_ns"
> +
> +/**
> + * VIR_DOMAIN_IOTHREAD_POLL_GROW:
> + *
> + * This provides a value for the dynamic polling adjustment algorithm to
> + * use to grow its polling interval up to the poll_max_ns value. A value
> + * of 0 (zero) allows the hypervisor to choose its own value. The algorithm
> + * to use for adjustment is hypervisor specific.
> + */
> +# define VIR_DOMAIN_IOTHREAD_POLL_GROW "poll_grow"
> +
> +/**
> + * VIR_DOMAIN_IOTHREAD_POLL_SHRINK:
> + *
> + * This provides a value for the dynamic polling adjustment algorithm to
> + * use to shrink its polling interval when the polling interval exceeds
> + * the poll_max_ns value. A value of 0 (zero) allows the hypervisor to
> + * choose its own value. The algorithm to use for adjustment is hypervisor
> + * specific.
> + */
> +# define VIR_DOMAIN_IOTHREAD_POLL_SHRINK "poll_shrink"
> +
> +int                  virDomainSetIOThreadParams(virDomainPtr domain,

On a completely unrelated note, this is stupid. I mean the amount of
spaces after 'int'. I wonder if a patch that reformats all the header
files would be accepted.

The ACK still holds.

> +                                                unsigned int iothread_id,
> +                                                virTypedParameterPtr params,
> +                                                int nparams,
> +                                                unsigned int flags);

Michal