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From: Yongseok Koh <yskoh@mellanox.com>
To: Andrew Rybchenko <arybchenko@solarflare.com>
Cc: wenzhuo.lu@intel.com, jingjing.wu@intel.com,
	olivier.matz@6wind.com, dev@dpdk.org,
	konstantin.ananyev@intel.com, adrien.mazarguil@6wind.com,
	nelio.laranjeiro@6wind.com
Subject: Re: [dpdk-dev] [PATCH v4 1/2] mbuf: support attaching external buffer to mbuf
Date: Tue, 24 Apr 2018 15:30:49 -0700	[thread overview]
Message-ID: <20180424223048.GB88208@yongseok-MBP.local> (raw)
In-Reply-To: <934e714e-3cba-7f5d-9fcf-4f96611d758f@solarflare.com>

On Tue, Apr 24, 2018 at 03:28:33PM +0300, Andrew Rybchenko wrote:
> On 04/24/2018 04:38 AM, Yongseok Koh wrote:
[...]
> > diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> > index 06eceba37..7f6507a66 100644
> > --- a/lib/librte_mbuf/rte_mbuf.h
> > +++ b/lib/librte_mbuf/rte_mbuf.h
> > @@ -326,7 +326,7 @@ extern "C" {
> >   		PKT_TX_MACSEC |		 \
> >   		PKT_TX_SEC_OFFLOAD)
> > -#define __RESERVED           (1ULL << 61) /**< reserved for future mbuf use */
> > +#define EXT_ATTACHED_MBUF    (1ULL << 61) /**< Mbuf having external buffer */
> 
> May be it should mention that shinfo is filled in.

Okay.

> >   #define IND_ATTACHED_MBUF    (1ULL << 62) /**< Indirect attached mbuf */
> > @@ -566,8 +566,24 @@ struct rte_mbuf {
> >   	/** Sequence number. See also rte_reorder_insert(). */
> >   	uint32_t seqn;
> > +	struct rte_mbuf_ext_shared_info *shinfo;
> 
> I think it would be useful to add comment that it is used in the case of
> RTE_MBUF_HAS_EXTBUF() only.

Oops, I missed that. Thanks.

[...]
> > +static inline char * __rte_experimental
> > +rte_pktmbuf_attach_extbuf(struct rte_mbuf *m, void *buf_addr,
> > +	rte_iova_t buf_iova, uint16_t buf_len,
> > +	struct rte_mbuf_ext_shared_info *shinfo,
> > +	rte_mbuf_extbuf_free_callback_t free_cb, void *fcb_opaque)
> > +{
> > +	void *buf_end = RTE_PTR_ADD(buf_addr, buf_len);
> 
> May I suggest to move it inside if (shinfo == NULL) to make it clear that it
> is not used if shinfo pointer is provided.

Done.

[...]
> >   static inline void rte_pktmbuf_attach(struct rte_mbuf *mi, struct rte_mbuf *m)
> >   {
> > -	struct rte_mbuf *md;
> > -
> >   	RTE_ASSERT(RTE_MBUF_DIRECT(mi) &&
> >   	    rte_mbuf_refcnt_read(mi) == 1);
> > -	/* if m is not direct, get the mbuf that embeds the data */
> > -	if (RTE_MBUF_DIRECT(m))
> > -		md = m;
> > -	else
> > -		md = rte_mbuf_from_indirect(m);
> > +	if (RTE_MBUF_HAS_EXTBUF(m)) {
> > +		rte_mbuf_ext_refcnt_update(m->shinfo, 1);
> > +		mi->ol_flags = m->ol_flags;
> > +	} else {
> > +		rte_mbuf_refcnt_update(rte_mbuf_from_indirect(m), 1);
> 
> It looks like handling of the direct mbuf is lost here. May be it is
> intentional
> to avoid branching since result will be the same for direct mbuf as well,
> but looks confusing. Deserves at least a comment which explains why.
> Ideally it should be proven by measurements.

Right, that was intentional to avoid the branch. Sometimes branch is more
expensive than arithmetic ops in core's pipeline. Will add a comment.

[...]
> > +static inline void
> > +__rte_pktmbuf_free_direct(struct rte_mbuf *m)
> > +{
> > +	struct rte_mbuf *md = rte_mbuf_from_indirect(m);
> 
> Shouldn't it be done after below assertion? Just to be less confusing.

Right. Done.

> > +
> > +	RTE_ASSERT(RTE_MBUF_INDIRECT(m));
> > +
> > +	if (rte_mbuf_refcnt_update(md, -1) == 0) {
> 
> It is not directly related to the changeset, but rte_pktmbuf_prefree_seg()
> has many optimizations which could be useful here:
>  - do not update if refcnt is 1
>  - do not set next/nb_seq if next is already NULL

Would be better to have a separate patch later.

Thanks,
Yongseok

> > +		md->next = NULL;
> > +		md->nb_segs = 1;
> > +		rte_mbuf_refcnt_set(md, 1);
> > +		rte_mbuf_raw_free(md);
> > +	}
> > +}
> 
> [...]

  parent reply	other threads:[~2018-04-24 22:31 UTC|newest]

Thread overview: 86+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-10  1:25 [dpdk-dev] [PATCH v1 0/6] net/mlx5: add Multi-Packet Rx support Yongseok Koh
2018-03-10  1:25 ` [dpdk-dev] [PATCH v1 1/6] mbuf: add buffer offset field for flexible indirection Yongseok Koh
2018-03-10  1:25 ` [dpdk-dev] [PATCH v1 2/6] net/mlx5: separate filling Rx flags Yongseok Koh
2018-03-10  1:25 ` [dpdk-dev] [PATCH v1 3/6] net/mlx5: add a function to rdma-core glue Yongseok Koh
2018-03-12  9:13   ` Nélio Laranjeiro
2018-03-10  1:25 ` [dpdk-dev] [PATCH v1 4/6] net/mlx5: add Multi-Packet Rx support Yongseok Koh
2018-03-12  9:20   ` Nélio Laranjeiro
2018-03-10  1:25 ` [dpdk-dev] [PATCH v1 5/6] net/mlx5: release Tx queue resource earlier than Rx Yongseok Koh
2018-03-10  1:25 ` [dpdk-dev] [PATCH v1 6/6] app/testpmd: conserve mbuf indirection flag Yongseok Koh
2018-04-02 18:50 ` [dpdk-dev] [PATCH v2 0/6] net/mlx5: add Multi-Packet Rx support Yongseok Koh
2018-04-02 18:50   ` [dpdk-dev] [PATCH v2 1/6] mbuf: add buffer offset field for flexible indirection Yongseok Koh
2018-04-03  8:26     ` Olivier Matz
2018-04-04  0:12       ` Yongseok Koh
2018-04-09 16:04         ` Olivier Matz
2018-04-10  1:59           ` Yongseok Koh
2018-04-11  0:25             ` Ananyev, Konstantin
2018-04-11  5:33               ` Yongseok Koh
2018-04-11 11:39                 ` Ananyev, Konstantin
2018-04-11 14:02                   ` Andrew Rybchenko
2018-04-11 17:18                     ` Yongseok Koh
2018-04-11 17:08                   ` Yongseok Koh
2018-04-12 16:34                     ` Ananyev, Konstantin
2018-04-12 18:58                       ` Yongseok Koh
2018-04-02 18:50   ` [dpdk-dev] [PATCH v2 2/6] net/mlx5: separate filling Rx flags Yongseok Koh
2018-04-02 18:50   ` [dpdk-dev] [PATCH v2 3/6] net/mlx5: add a function to rdma-core glue Yongseok Koh
2018-04-02 18:50   ` [dpdk-dev] [PATCH v2 4/6] net/mlx5: add Multi-Packet Rx support Yongseok Koh
2018-04-02 18:50   ` [dpdk-dev] [PATCH v2 5/6] net/mlx5: release Tx queue resource earlier than Rx Yongseok Koh
2018-04-02 18:50   ` [dpdk-dev] [PATCH v2 6/6] app/testpmd: conserve mbuf indirection flag Yongseok Koh
2018-04-19  1:11 ` [dpdk-dev] [PATCH v3 1/2] mbuf: support attaching external buffer to mbuf Yongseok Koh
2018-04-19  1:11   ` [dpdk-dev] [PATCH v3 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-23 11:53   ` [dpdk-dev] [PATCH v3 1/2] mbuf: support attaching external buffer to mbuf Ananyev, Konstantin
2018-04-24  2:04     ` Yongseok Koh
2018-04-25 13:16       ` Ananyev, Konstantin
2018-04-25 16:44         ` Yongseok Koh
2018-04-25 18:05           ` Ananyev, Konstantin
2018-04-23 16:18   ` Olivier Matz
2018-04-24  1:29     ` Yongseok Koh
2018-04-24 15:36       ` Olivier Matz
2018-04-24  1:38 ` [dpdk-dev] [PATCH v4 " Yongseok Koh
2018-04-24  1:38   ` [dpdk-dev] [PATCH v4 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-24  5:01   ` [dpdk-dev] [PATCH v4 1/2] mbuf: support attaching external buffer to mbuf Stephen Hemminger
2018-04-24 11:47     ` Yongseok Koh
2018-04-24 12:28   ` Andrew Rybchenko
2018-04-24 16:02     ` Olivier Matz
2018-04-24 18:21       ` [dpdk-dev] ***Spam*** " Andrew Rybchenko
2018-04-24 19:15         ` [dpdk-dev] " Olivier Matz
2018-04-24 20:22           ` Thomas Monjalon
2018-04-24 21:53             ` Yongseok Koh
2018-04-24 22:15               ` Thomas Monjalon
2018-04-25  8:21               ` Olivier Matz
2018-04-25 15:06             ` Stephen Hemminger
2018-04-24 23:34           ` Yongseok Koh
2018-04-25 14:45             ` Andrew Rybchenko
2018-04-25 17:40               ` Yongseok Koh
2018-04-25  8:28       ` Olivier Matz
2018-04-25  9:08         ` Yongseok Koh
2018-04-25  9:19           ` Yongseok Koh
2018-04-25 20:00             ` Olivier Matz
2018-04-25 22:54               ` Yongseok Koh
2018-04-24 22:30     ` Yongseok Koh [this message]
2018-04-25  2:53 ` [dpdk-dev] [PATCH v5 " Yongseok Koh
2018-04-25  2:53   ` [dpdk-dev] [PATCH v5 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-25 13:31   ` [dpdk-dev] [PATCH v5 1/2] mbuf: support attaching external buffer to mbuf Ananyev, Konstantin
2018-04-25 17:06     ` Yongseok Koh
2018-04-25 17:23       ` Ananyev, Konstantin
2018-04-25 18:02         ` Yongseok Koh
2018-04-25 18:22           ` Yongseok Koh
2018-04-25 18:30             ` Yongseok Koh
2018-04-26  1:10 ` [dpdk-dev] [PATCH v6 " Yongseok Koh
2018-04-26  1:10   ` [dpdk-dev] [PATCH v6 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-26 11:39   ` [dpdk-dev] [PATCH v6 1/2] mbuf: support attaching external buffer to mbuf Ananyev, Konstantin
2018-04-26 16:05   ` Andrew Rybchenko
2018-04-26 16:10     ` Thomas Monjalon
2018-04-26 19:42       ` Olivier Matz
2018-04-26 19:58         ` Thomas Monjalon
2018-04-26 20:07           ` Olivier Matz
2018-04-26 20:24             ` Thomas Monjalon
2018-04-26 17:18     ` Yongseok Koh
2018-04-26 19:45       ` Olivier Matz
2018-04-27  0:01 ` [dpdk-dev] [PATCH v7 " Yongseok Koh
2018-04-27  0:01   ` [dpdk-dev] [PATCH v7 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-27  8:00     ` Andrew Rybchenko
2018-04-27  7:22   ` [dpdk-dev] [PATCH v7 1/2] mbuf: support attaching external buffer to mbuf Andrew Rybchenko
2018-04-27 17:22 ` [dpdk-dev] [PATCH v8 " Yongseok Koh
2018-04-27 17:22   ` [dpdk-dev] [PATCH v8 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-27 18:09   ` [dpdk-dev] [PATCH v8 1/2] mbuf: support attaching external buffer to mbuf Thomas Monjalon

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