Re: [dpdk-dev] [PATCH v7 1/2] ring: add reset API to flush the ring when not in use

["Gavin Hu (Arm Technology China)" <Gavin.Hu@arm.com>]

> -----Original Message-----
> From: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
> Sent: Friday, July 12, 2019 11:41 PM
> To: Gavin Hu (Arm Technology China) <Gavin.Hu@arm.com>; Olivier Matz
> <olivier.matz@6wind.com>
> Cc: thomas@monjalon.net; dev@dpdk.org; nd <nd@arm.com>;
> jerinj@marvell.com; hemant.agrawal@nxp.com; Nipun.gupta@nxp.com;
> i.maximets@samsung.com; stable@dpdk.org; Ruifeng Wang (Arm
> Technology China) <Ruifeng.Wang@arm.com>; nd <nd@arm.com>
> Subject: RE: [dpdk-dev] [PATCH v7 1/2] ring: add reset API to flush the ring
> when not in use
> 
> <snip>
> 
> > > > > > >
> > > > > > > 29/03/2019 15:17, Olivier Matz:
> > > > > > > > Hi,
> > > > > > > >
> > > > > > > > On Fri, Mar 15, 2019 at 11:31:25AM +0800, Gavin Hu wrote:
> > > > > > > > > Currently, the flush is done by dequeuing the ring in a while
> loop.
> > > It is
> > > > > > > > > much simpler to flush the queue by resetting the head and
> > > > > > > > > tail
> > > indices.
> > > > > > > > >
> > > > > > > > > Fixes: af75078fece3 ("first public release")
> > > > > > > > > Cc: stable@dpdk.org
> > > > > > > > >
> > > > > > > > > Signed-off-by: Gavin Hu <gavin.hu@arm.com>
> > > > > > > > > Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
> > > > > > > > > Reviewed-by: Honnappa Nagarahalli
> > > <honnappa.nagarahalli@arm.com>
> > > > > > > > > ---
> > > > > > > > > --- a/lib/librte_ring/rte_ring_version.map
> > > > > > > > > +++ b/lib/librte_ring/rte_ring_version.map
> > > > > > > > > @@ -17,3 +17,10 @@ DPDK_2.2 {
> > > > > > > > >  	rte_ring_free;
> > > > > > > > >
> > > > > > > > >  } DPDK_2.0;
> > > > > > > > > +
> > > > > > > > > +EXPERIMENTAL {
> > > > > > > > > +    global:
> > > > > > > > > +
> > > > > > > > > +	rte_ring_reset;
> > > > > > > > > +
> > > > > > > > > +};
> > > > > > > >
> > > > > > > > To me, a static inline function does not need to be added in
> > > > > > > > rte_ring_version.map (or is it due to a check script
> > > > > > > > checking the __rte_experimental tag ?). I found at least one
> > > > > > > > commit where it is not the case:
> > > > > > > > c277b34c1b3b ("mbuf: add function returning buffer address")
> > > > > > > >
> > > > > > > > There are 2 options:
> > > > > > > > 1- remove the rte_ring_version.map part of the patch.
> > > > > > > > 2- change the static inline function into a standard function.
> > > > > > > >
> > > > > > > > I would prefer 2-, because it allows to keep an api/abi
> > > > > > > > compat layer in the future.
> > > > > > >
> > > > > > > There are no news about this patch.
> > > > > > > I classify it as changes requested.
> > > > > > >
> > > > > > Sorry for missed your comments for long time, I just submitted v8.
> > > > > > I took the first option as it is in the data path and to keep
> > > > > > consistent to
> > > its
> > > > > neighboring functions.
> > > > >
> > > > > Could you give a little more context about why you need to reset
> > > > > the ring in the data path? I see that it is used in
> > > > > rte_hash_reset(), but in my thinking, this was more used at init/exit.
> > > > Sorry，literally it is in the control path, but I was impressed it
> > > > will impact
> > > the
> > > > Data path performance when discussing this patch with Honnappa.
> > >
> > > I'm asking this because given the recent discussions about ABI
> > > stability, I'd like to avoid defining a new static inline if it is not required.
> >
> > Ok, will take 2nd option in V9, and squash the two patches into one,
> otherwise
> > it reports the following error:
> > "error: ‘rte_ring_reset’ defined but not used [-Werror=unused-function]"
> Agree, it is a control path function, does not impact any data path
> performance. It should not be inline.
Thanks for your clarification, I submitted v9 for this.