[dpdk-dev] [PATCH v7 4/8] vhost: rxtx: use queue id instead of constant ring index

[Ananyev, Konstantin]

> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Xie, Huawei
> Sent: Wednesday, October 21, 2015 8:16 AM
> To: Stephen Hemminger; Yuanhan Liu
> Cc: dev at dpdk.org; marcel at redhat.com; Michael S. Tsirkin; Changchun Ouyang
> Subject: Re: [dpdk-dev] [PATCH v7 4/8] vhost: rxtx: use queue id instead of constant ring index
> 
> On 10/21/2015 12:44 PM, Stephen Hemminger wrote:
> > On Wed, 21 Oct 2015 11:48:10 +0800
> > Yuanhan Liu <yuanhan.liu at linux.intel.com> wrote:
> >
> >>
> >> +static inline int __attribute__((always_inline))
> >> +is_valid_virt_queue_idx(uint32_t virtq_idx, int is_tx, uint32_t max_qp_idx)
> >> +{
> >> +	if ((is_tx ^ (virtq_idx & 0x1)) ||
> >> +	    (virtq_idx >= max_qp_idx * VIRTIO_QNUM))
> >> +		return 0;
> >> +
> >> +	return 1;
> >> +}
> > minor nits:
> >  * this doesn't need to be marked as always inline,
> >     that is as they say in English "shooting a fly with a bazooka"
> Stephen:
> always_inline "forces" the compiler to inline this function, like a macro.
> When should it be used or is it not preferred at all?

I also don't understand what's wrong with using 'always_inline' here.
As I understand the author wants compiler to *always inline* that function.
So seems perfectly ok to use it here.
As I remember just 'inline' is sort of recommendation that compiler is free to ignore.
Konstantin 

> 
> >  * prefer to just return logical result rather than have conditional:
> >  * for booleans prefer the <stdbool.h> type boolean.
> >
> > static bool
> > is_valid_virt_queue_idx(uint32_t virtq_idx, bool is_tx, uint32_t max_qp_idx)
> > {
> > 	return (is_tx ^ (virtq_idx & 1)) ||
> > 		virtq_idx >= max_qp_idx * VIRTIO_QNUM;
> > }
> >