|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] x86: make the dom0_max_vcpus option more flexible
>>> On 04.05.12 at 20:18, David Vrabel <david.vrabel@xxxxxxxxxx> wrote:
> On 04/05/12 17:26, David Vrabel wrote:
>> On 04/05/12 17:12, Jan Beulich wrote:
>>>>>> On 04.05.12 at 18:01, David Vrabel <david.vrabel@xxxxxxxxxx> wrote:
>>>> From: David Vrabel <david.vrabel@xxxxxxxxxx>
>>>>
>>>> The dom0_max_vcpus command line option only allows the exact number of
>>>> VCPUs for dom0 to be set. It is not possible to say "up to N VCPUs
>>>> but no more than the number physically present."
>>>>
>>>> Add min: and max: prefixes to the option to set a minimum number of
>>>> VCPUs, and a maximum which does not exceed the number of PCPUs.
>>>>
>>>> For example, with "dom0_max_vcpus=min:4,max:8":
>>>
>>> Both "...max...=min:..." and "...max...=max:" look pretty odd to me;
>>> how about simply allowing a range along with a simple number (since
>>> negative values make no sense, omitting either side of the range would
>>> be supportable if necessary.
>>
>> I was copying the way dom0_mem worked but yeah, it's not very pretty.
>>
>> Is dom0_max_vcpus=<min>-<max> (e.g., dom0_max_vcpus=4-8) what you were
>> thinking of?
>>
>> Using a single value would have to set both <min> and <max> or the
>> behaviour of the option changes (i.e., =N is the same as =N-N).
>
> This is what I ended up with.
>
> 8<------------------------------
> From af1543965db76ab81139de7f072a7c4daf61157f Mon Sep 17 00:00:00 2001
> From: David Vrabel <david.vrabel@xxxxxxxxxx>
> Date: Fri, 4 May 2012 16:09:52 +0100
> Subject: [PATCH] x86: make the dom0_max_vcpus option more flexible
>
> The dom0_max_vcpus command line option only allows the exact number of
> VCPUs for dom0 to be set. It is not possible to say "up to N VCPUs
> but no more than the number physically present."
>
> Allow a range for the option to set a minimum number of VCPUs, and a
> maximum which does not exceed the number of PCPUs.
>
> For example, with "dom0_max_vcpus=4-8":
>
> PCPUs Dom0 VCPUs
> 2 4
> 4 4
> 6 6
> 8 8
> 10 8
>
> Existing command lines with "dom0_max_vcpus=N" still work as before.
>
> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
But I'm not sure whether this qualifies for going in for 4.2...
Jan
> ---
> docs/misc/xen-command-line.markdown | 29 +++++++++++++++++++++--
> xen/arch/x86/domain_build.c | 43 +++++++++++++++++++++++++---------
> 2 files changed, 57 insertions(+), 15 deletions(-)
>
> diff --git a/docs/misc/xen-command-line.markdown
> b/docs/misc/xen-command-line.markdown
> index a6195f2..4e4f713 100644
> --- a/docs/misc/xen-command-line.markdown
> +++ b/docs/misc/xen-command-line.markdown
> @@ -272,10 +272,33 @@ Specify the bit width of the DMA heap.
>
> ### dom0\_ioports\_disable
> ### dom0\_max\_vcpus
> -> `= <integer>`
>
> -Specify the maximum number of vcpus to give to dom0. This defaults
> -to the number of pcpus on the host.
> +Either:
> +
> +> `= <integer>`.
> +
> +The number of VCPUs to give to dom0. This number of VCPUs can be more
> +than the number of PCPUs on the host. The default is the number of
> +PCPUs.
> +
> +Or:
> +
> +> `= <min>-<max>` where `<min>` and `<max>` are integers.
> +
> +Gives dom0 a number of VCPUs equal to the number of PCPUs, but always
> +at least `<min>` and no more than `<max>`. Using `<min>` may give
> +more VCPUs than PCPUs. `<min>` or `<max>` may be omitted and the
> +defaults of 1 and unlimited respectively are used instead.
> +
> +For example, with `dom0_max_vcpus=4-8`:
> +
> + Number of
> + PCPUs | Dom0 VCPUs
> + 2 | 4
> + 4 | 4
> + 6 | 6
> + 8 | 8
> + 10 | 8
>
> ### dom0\_mem (ia64)
> > `= <size>`
> diff --git a/xen/arch/x86/domain_build.c b/xen/arch/x86/domain_build.c
> index b3c5d4c..686b626 100644
> --- a/xen/arch/x86/domain_build.c
> +++ b/xen/arch/x86/domain_build.c
> @@ -82,20 +82,39 @@ static void __init parse_dom0_mem(const char *s)
> }
> custom_param("dom0_mem", parse_dom0_mem);
>
> -static unsigned int __initdata opt_dom0_max_vcpus;
> -integer_param("dom0_max_vcpus", opt_dom0_max_vcpus);
> +static unsigned int __initdata opt_dom0_max_vcpus_min = 1;
> +static unsigned int __initdata opt_dom0_max_vcpus_max = UINT_MAX;
> +
> +static void __init parse_dom0_max_vcpus(const char *s)
> +{
> + if (*s == '-') /* -M */
> + opt_dom0_max_vcpus_max = simple_strtoul(s + 1, &s, 0);
> + else { /* N, N-, or N-M */
> + opt_dom0_max_vcpus_min = simple_strtoul(s, &s, 0);
> + if (*s++ == '\0') /* N */
> + opt_dom0_max_vcpus_max = opt_dom0_max_vcpus_min;
> + else if (*s != '\0') /* N-M */
> + opt_dom0_max_vcpus_max = simple_strtoul(s, &s, 0);
> + }
> +}
> +custom_param("dom0_max_vcpus", parse_dom0_max_vcpus);
>
> struct vcpu *__init alloc_dom0_vcpu0(void)
> {
> - if ( opt_dom0_max_vcpus == 0 )
> - opt_dom0_max_vcpus = num_cpupool_cpus(cpupool0);
> - if ( opt_dom0_max_vcpus > MAX_VIRT_CPUS )
> - opt_dom0_max_vcpus = MAX_VIRT_CPUS;
> + unsigned max_vcpus;
> +
> + max_vcpus = num_cpupool_cpus(cpupool0);
> + if ( opt_dom0_max_vcpus_min > max_vcpus )
> + max_vcpus = opt_dom0_max_vcpus_min;
> + if ( opt_dom0_max_vcpus_max < max_vcpus )
> + max_vcpus = opt_dom0_max_vcpus_max;
> + if ( max_vcpus > MAX_VIRT_CPUS )
> + max_vcpus = MAX_VIRT_CPUS;
>
> - dom0->vcpu = xzalloc_array(struct vcpu *, opt_dom0_max_vcpus);
> + dom0->vcpu = xzalloc_array(struct vcpu *, max_vcpus);
> if ( !dom0->vcpu )
> return NULL;
> - dom0->max_vcpus = opt_dom0_max_vcpus;
> + dom0->max_vcpus = max_vcpus;
>
> return alloc_vcpu(dom0, 0, 0);
> }
> @@ -185,11 +204,11 @@ static unsigned long __init compute_dom0_nr_pages(
> unsigned long max_pages = dom0_max_nrpages;
>
> /* Reserve memory for further dom0 vcpu-struct allocations... */
> - avail -= (opt_dom0_max_vcpus - 1UL)
> + avail -= (d->max_vcpus - 1UL)
> << get_order_from_bytes(sizeof(struct vcpu));
> /* ...and compat_l4's, if needed. */
> if ( is_pv_32on64_domain(d) )
> - avail -= opt_dom0_max_vcpus - 1;
> + avail -= d->max_vcpus - 1;
>
> /* Reserve memory for iommu_dom0_init() (rough estimate). */
> if ( iommu_enabled )
> @@ -883,10 +902,10 @@ int __init construct_dom0(
> for ( i = 0; i < XEN_LEGACY_MAX_VCPUS; i++ )
> shared_info(d, vcpu_info[i].evtchn_upcall_mask) = 1;
>
> - printk("Dom0 has maximum %u VCPUs\n", opt_dom0_max_vcpus);
> + printk("Dom0 has maximum %u VCPUs\n", d->max_vcpus);
>
> cpu = cpumask_first(cpupool0->cpu_valid);
> - for ( i = 1; i < opt_dom0_max_vcpus; i++ )
> + for ( i = 1; i < d->max_vcpus; i++ )
> {
> cpu = cpumask_cycle(cpu, cpupool0->cpu_valid);
> (void)alloc_vcpu(d, i, cpu);
> --
> 1.7.2.5
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |