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From: Phil Yang <Phil.Yang@arm.com>
To: Olivier Matz <olivier.matz@6wind.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
	"stephen@networkplumber.org" <stephen@networkplumber.org>,
	"david.marchand@redhat.com" <david.marchand@redhat.com>,
	"drc@linux.vnet.ibm.com" <drc@linux.vnet.ibm.com>,
	Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>,
	Ruifeng Wang <Ruifeng.Wang@arm.com>, nd <nd@arm.com>
Subject: Re: [dpdk-dev] [PATCH v3] mbuf: use C11 atomic built-ins for refcnt operations
Date: Thu, 9 Jul 2020 13:00:31 +0000
Message-ID: <VE1PR08MB46409CA13FA629FA0217F45FE9640@VE1PR08MB4640.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <20200709110345.GR5869@platinum>

Hi Oliver,

> -----Original Message-----
> From: Olivier Matz <olivier.matz@6wind.com>
> Sent: Thursday, July 9, 2020 7:04 PM
> To: Phil Yang <Phil.Yang@arm.com>
> Cc: dev@dpdk.org; stephen@networkplumber.org;
> david.marchand@redhat.com; drc@linux.vnet.ibm.com; Honnappa
> Nagarahalli <Honnappa.Nagarahalli@arm.com>; Ruifeng Wang
> <Ruifeng.Wang@arm.com>; nd <nd@arm.com>
> Subject: Re: [PATCH v3] mbuf: use C11 atomic built-ins for refcnt operations
> 
> Hi Phil,
> 
> On Thu, Jul 09, 2020 at 06:10:42PM +0800, Phil Yang wrote:
> > Use C11 atomic built-ins with explicit ordering instead of rte_atomic
> > ops which enforce unnecessary barriers on aarch64.
> >
> > Signed-off-by: Phil Yang <phil.yang@arm.com>
> > Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
> > ---
> > v3:
> > 1.Fix ABI breakage.
> > 2.Simplify data type cast.
> >
> > v2:
> > Fix ABI issue: revert the rte_mbuf_ext_shared_info struct refcnt field
> > to refcnt_atomic.
> >
> >  lib/librte_mbuf/rte_mbuf.c      |  1 -
> >  lib/librte_mbuf/rte_mbuf.h      | 19 ++++++++++---------
> >  lib/librte_mbuf/rte_mbuf_core.h |  2 +-
> >  3 files changed, 11 insertions(+), 11 deletions(-)
> >
<snip>
> >
> >  	/* Reinitialize counter before mbuf freeing. */
> > diff --git a/lib/librte_mbuf/rte_mbuf_core.h
> b/lib/librte_mbuf/rte_mbuf_core.h
> > index 16600f1..d65d1c8 100644
> > --- a/lib/librte_mbuf/rte_mbuf_core.h
> > +++ b/lib/librte_mbuf/rte_mbuf_core.h
> > @@ -679,7 +679,7 @@ typedef void
> (*rte_mbuf_extbuf_free_callback_t)(void *addr, void *opaque);
> >  struct rte_mbuf_ext_shared_info {
> >  	rte_mbuf_extbuf_free_callback_t free_cb; /**< Free callback
> function */
> >  	void *fcb_opaque;                        /**< Free callback argument */
> > -	rte_atomic16_t refcnt_atomic;        /**< Atomically accessed refcnt */
> > +	uint16_t refcnt_atomic;              /**< Atomically accessed refcnt */
> >  };
> 
> To avoid an API breakage (i.e. currently, an application that accesses
> to refcnt_atomic expects that its type is rte_atomic16_t), I suggest to
> do the same than in the mbuf struct:
> 
> 	union {
> 		rte_atomic16_t refcnt_atomic;
> 		uint16_t refcnt;
> 	};
> 
> I hope the ABI checker won't complain.
> 
> It will also be better for 20.11 when the deprecated fields will be
> renamed: the remaining one will be called 'refcnt' in both mbuf and
> mbuf_ext_shared_info.

Got it. I agree with you.
It should work. In my local test machine, the ABI checker happy with this approach. 
Once the test is done, I will upstream the new patch.

Appreciate your comments.

Thanks,
Phil

  reply	other threads:[~2020-07-09 13:00 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-11 10:26 [dpdk-dev] [PATCH] mbuf: use c11 atomics " Phil Yang
2020-07-03 15:38 ` David Marchand
2020-07-06  8:03   ` Phil Yang
2020-07-07 10:10 ` [dpdk-dev] [PATCH v2] mbuf: use C11 " Phil Yang
2020-07-07 17:13   ` Stephen Hemminger
2020-07-08  4:48     ` Phil Yang
2020-07-08 11:43       ` Olivier Matz
2020-07-09  9:52         ` Phil Yang
2020-07-08  5:11   ` Phil Yang
2020-07-08 11:44   ` Olivier Matz
2020-07-09 10:00     ` Phil Yang
2020-07-09 10:10   ` [dpdk-dev] [PATCH v3] mbuf: use C11 atomic built-ins " Phil Yang
2020-07-09 11:03     ` Olivier Matz
2020-07-09 13:00       ` Phil Yang [this message]
2020-07-09 13:31         ` Honnappa Nagarahalli
2020-07-09 14:10           ` Phil Yang
2020-07-09 15:58     ` [dpdk-dev] [PATCH v4 1/2] " Phil Yang
2020-07-09 15:58       ` [dpdk-dev] [PATCH v4 2/2] doc: announce deprecation of refcnt atomic member Phil Yang
2020-07-10  2:55         ` Ruifeng Wang
2020-07-13 15:54           ` Phil Yang
2020-07-14 10:41         ` Ananyev, Konstantin
2020-07-15 12:29       ` [dpdk-dev] [PATCH v4 1/2] mbuf: use C11 atomic built-ins for refcnt operations David Marchand
2020-07-15 12:49         ` Aaron Conole
2020-07-15 16:29         ` Phil Yang
2020-07-16  4:16         ` Phil Yang
2020-07-16 11:30           ` David Marchand
2020-07-16 13:20             ` Dodji Seketeli
2020-07-16 19:11               ` David Marchand
2020-07-17  4:41                 ` Phil Yang
2020-07-16 11:32       ` Olivier Matz
2020-07-17  4:36       ` [dpdk-dev] [PATCH v5 1/2] mbuf: use C11 atomic builtins " Phil Yang
2020-07-17  4:36         ` [dpdk-dev] [PATCH v5 2/2] doc: announce deprecation of refcnt atomic member Phil Yang
2020-07-17 11:45           ` Olivier Matz
2020-07-17 14:32           ` David Marchand
2020-07-17 14:35             ` David Marchand
2020-07-17 16:06               ` Ananyev, Konstantin
2020-07-17 16:20               ` Bruce Richardson
2020-07-21  8:35                 ` David Marchand
2020-07-21  8:48                   ` Ananyev, Konstantin
2020-07-21  8:37         ` [dpdk-dev] [PATCH v5 1/2] mbuf: use C11 atomic builtins for refcnt operations David Marchand

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