Re: [PATCH] KVM: halt_polling: allow tuning of grow/shrink

[Christian Borntraeger <borntraeger@de.ibm.com>]

On 02/09/2016 01:00 PM, Christian Borntraeger wrote:
> Right now halt_poll_ns can be change during runtime. The
> grow and shrink factors can only be set during module load.
> Let's make this consistent and allow changes during runtime.
> To avoid dirty tricky like setting shrink to 0 after the
> check for 0, use READ_ONCE to get a consistent number for
> all cases.
> 
> Cc: Wanpeng Li <wanpeng.li@hotmail.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  virt/kvm/kvm_main.c | 22 ++++++++++++----------
>  1 file changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 726d7c8..eafea6f 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -72,11 +72,11 @@ module_param(halt_poll_ns, uint, S_IRUGO | S_IWUSR);
> 
>  /* Default doubles per-vcpu halt_poll_ns. */
>  static unsigned int halt_poll_ns_grow = 2;
> -module_param(halt_poll_ns_grow, int, S_IRUGO);
> +module_param(halt_poll_ns_grow, int, S_IRUGO | S_IWUSR);

Please let me know if I should respin with a global fixup
regarding signedness:

Right now we have a mix of
uint:
>  static unsigned int halt_poll_ns_grow = 2;
int:
> +module_param(halt_poll_ns_grow, int, S_IRUGO | S_IWUSR);
int:
> -	int old, val;

I think having everything as unsigned int would be
the right thing.

Christian