On Tue, 24 Jan 2017 19:57:13 +0400, Ilya Matveychikov <matvejchi...@gmail.com> wrote: > > On Jan 24, 2017, at 4:56 PM, Olivier MATZ <olivier.m...@6wind.com> > > wrote: > > > > Hi, > > > > On Sat, 21 Jan 2017 16:28:29 +0000, "Ananyev, Konstantin" > > <konstantin.anan...@intel.com> wrote: > >>> -----Original Message----- > >>> From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Ilya > >>> Matveychikov Sent: Saturday, January 21, 2017 3:08 PM > >>> To: Yigit, Ferruh <ferruh.yi...@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.yi...@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 <matvejchi...@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.m...@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. > > In my application I need to do IPv4 fragments reassembly. There is no > explicit limit of number of fragments in datagram, so I’m trying to > avoid any limitations and `nb_segs` here is a constraint for me. > Expanding it from 8-bit to 16-bit can solve that issue for me. But I > don’t remember are there any other places in DPDK where we need to > know how many segments are in the packet? I mean that is `nb_segs` > required at all? >
Yes, it is used for instance in some PMDs to know how many tx ring descriptors are needed to send a packet. Thank you for the explanation. As you probably seen, I'm proposing to extend the nb_segs to 16 bits in my latest RFC patchset. Regards, Olivier
