Re: [PATCHv1] xen: increase default number of PIRQs for hardware domains

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 03/12/14 16:04, David Vrabel wrote:
> The default limit for the number of PIRQs for hardware domains (dom0)
> is not sufficient for some (x86) systems.
>
> Since the pirq structures are individually and dynamically allocated,
> the limit for hardware domains may be increased to the number of
> possible IRQs.
>
> The extra_guest_irqs command line option now only allows changes to
> the domU value.  Any argument for dom0 is ignored.
>
> Signed-off-by: David Vrabel <david.vrabel@citrix.com>

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

> ---
>  docs/misc/xen-command-line.markdown |   11 ++++-------
>  xen/common/domain.c                 |    7 +------
>  2 files changed, 5 insertions(+), 13 deletions(-)
>
> diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown
> index 0866df2..d352031 100644
> --- a/docs/misc/xen-command-line.markdown
> +++ b/docs/misc/xen-command-line.markdown
> @@ -594,15 +594,12 @@ except for debugging purposes.
>  Force or disable use of EFI runtime services.
>  
>  ### extra\_guest\_irqs
> -> `= [<domU number>][,<dom0 number>]`
> +> `= [<number>]`
>  
> -> Default: `32,256`
> +> Default: `32`
>  
> -Change the number of PIRQs available for guests.  The optional first number is
> -common for all domUs, while the optional second number (preceded by a comma)
> -is for dom0.  Changing the setting for domU has no impact on dom0 and vice
> -versa.  For example to change dom0 without changing domU, use
> -`extra_guest_irqs=,512`
> +Change the number of PIRQs available for guests. This limit does not
> +apply to hardware domains (dom0).
>  
>  ### flask\_enabled
>  > `= <integer>`
> diff --git a/xen/common/domain.c b/xen/common/domain.c
> index 4a62c1d..a88d829 100644
> --- a/xen/common/domain.c
> +++ b/xen/common/domain.c
> @@ -231,14 +231,11 @@ static int late_hwdom_init(struct domain *d)
>  #endif
>  }
>  
> -static unsigned int __read_mostly extra_dom0_irqs = 256;
>  static unsigned int __read_mostly extra_domU_irqs = 32;
>  static void __init parse_extra_guest_irqs(const char *s)
>  {
>      if ( isdigit(*s) )
>          extra_domU_irqs = simple_strtoul(s, &s, 0);
> -    if ( *s == ',' && isdigit(*++s) )
> -        extra_dom0_irqs = simple_strtoul(s, &s, 0);
>  }
>  custom_param("extra_guest_irqs", parse_extra_guest_irqs);
>  
> @@ -324,10 +321,8 @@ struct domain *domain_create(
>          atomic_inc(&d->pause_count);
>  
>          if ( !is_hardware_domain(d) )
> -            d->nr_pirqs = nr_static_irqs + extra_domU_irqs;
> +            d->nr_pirqs = min(nr_static_irqs + extra_domU_irqs, nr_irqs);
>          else
> -            d->nr_pirqs = nr_static_irqs + extra_dom0_irqs;
> -        if ( d->nr_pirqs > nr_irqs )
>              d->nr_pirqs = nr_irqs;
>  
>          radix_tree_init(&d->pirq_tree);