Re: [dpdk-dev] [PATCH] mbuf: remove redundant line in rte_pktmbuf_attach

[Olivier MATZ <olivier.matz@6wind.com>]

Hi,

On Sat, 21 Jan 2017 16:28:29 +0000, "Ananyev, Konstantin"
<konstantin.ananyev@intel.com> wrote:
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Ilya
> > Matveychikov Sent: Saturday, January 21, 2017 3:08 PM
> > To: Yigit, Ferruh <ferruh.yigit@intel.com>
> > Cc: dev@dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH] mbuf: remove redundant line in
> > rte_pktmbuf_attach
> > 
> >   
> > > On Jan 20, 2017, at 4:08 PM, Ferruh Yigit
> > > <ferruh.yigit@intel.com> wrote:
> > >
> > > On 1/20/2017 12:19 AM, Ilya Matveychikov wrote:  
> > >> mi->next will be assigned to NULL few lines later, trivial patch
> > >>
> > >> Signed-off-by: Ilya V. Matveychikov <matvejchikov@gmail.com>
> > >> ---
> > >> lib/librte_mbuf/rte_mbuf.h | 1 -
> > >> 1 file changed, 1 deletion(-)
> > >>
> > >> diff --git a/lib/librte_mbuf/rte_mbuf.h
> > >> b/lib/librte_mbuf/rte_mbuf.h index ead7c6e..5589d54 100644
> > >> --- a/lib/librte_mbuf/rte_mbuf.h
> > >> +++ b/lib/librte_mbuf/rte_mbuf.h
> > >> @@ -1139,7 +1139,6 @@ static inline void
> > >> rte_pktmbuf_attach(struct rte_mbuf *mi, struct rte_mbuf *m)
> > >> mi->buf_addr = m->buf_addr; mi->buf_len = m->buf_len;
> > >>
> > >> -	mi->next = m->next;  
> > >

Fixes: ea672a8b1655 ("mbuf: remove the rte_pktmbuf structure")

Acked-by: Olivier Matz <olivier.matz@6wind.com>


> > > Do you know why attaching mbuf is not supporting multi-segment?  
> 
> This is supported, but you have to do it segment by segment.
> Actually  rte_pktmbuf_clone() does that.
> Konstantin
> 
> 
> > > Perhaps this can be documented in function comment, as one of the
> > > "not supported" items.  
> > 
> > No, I don’t know. For my application I’ve found that nb_segs with
> > it’s limit in 256 segments is very annoying and I’ve decided not to
> > use DPDK functions that dealt with nb_segs… But it is not about the
> > rte_pktmbuf_attach() function and the patch. 


Out of curiosity, can you explain why your application needs more
than 256 segments? When we were discussing the possibility of extending
this field to 16 bits, Konstantin convinced me that it was not so
useful.


Thanks,
Olivier