| Message ID | 1530200511-77186-6-git-send-email-tiago.lam@intel.com |
|---|---|
| State | Superseded |
| Delegated to: | Ian Stokes |
| Headers | show |
| Series | Support multi-segment mbufs | expand |
On 28 Jun 2018, at 17:41, Tiago Lam wrote: > When a dp_packet is from a DPDK source, and it contains multi-segment > mbufs, the data_len is not equal to the packet size, pkt_len. Instead, > the data_len of each mbuf in the chain should be considered while > distributing the new (provided) size. > > To account for the above dp_packet_set_size() has been changed so > that, > in the multi-segment mbufs case, only the data_len on the last mbuf of > the chain and the total size of the packet, pkt_len, are changed. The > data_len on the intermediate mbufs preceeding the last mbuf is not > changed by dp_packet_set_size(). Furthermore, in some cases > dp_packet_set_size() may be used to set a smaller size than the > current > packet size, thus effectively trimming the end of the packet. In the > multi-segment mbufs case this may lead to lingering mbufs that may > need > freeing. > > __dp_packet_set_data() now also updates an mbufs' data_len after > setting > the data offset. This is so that both fields are always in sync for > each > mbuf in a chain. > > Co-authored-by: Michael Qiu <qiudayu@chinac.com> > Co-authored-by: Mark Kavanagh <mark.b.kavanagh@intel.com> > Co-authored-by: Przemyslaw Lal <przemyslawx.lal@intel.com> > Co-authored-by: Marcin Ksiadz <mksiadz@gmail.com> > Co-authored-by: Yuanhan Liu <yliu@fridaylinux.org> > > Signed-off-by: Michael Qiu <qiudayu@chinac.com> > Signed-off-by: Mark Kavanagh <mark.b.kavanagh@intel.com> > Signed-off-by: Przemyslaw Lal <przemyslawx.lal@intel.com> > Signed-off-by: Marcin Ksiadz <mksiadz@gmail.com> > Signed-off-by: Yuanhan Liu <yliu@fridaylinux.org> > Signed-off-by: Tiago Lam <tiago.lam@intel.com> > --- > lib/dp-packet.h | 67 > ++++++++++++++++++++++++++++++++++++++++++++++----------- > 1 file changed, 55 insertions(+), 12 deletions(-) > > diff --git a/lib/dp-packet.h b/lib/dp-packet.h > index c612ad4..d8cd35c 100644 > --- a/lib/dp-packet.h > +++ b/lib/dp-packet.h > @@ -429,17 +429,44 @@ dp_packet_size(const struct dp_packet *b) > static inline void > dp_packet_set_size(struct dp_packet *b, uint32_t v) > { > - /* netdev-dpdk does not currently support segmentation; > consequently, for > - * all intents and purposes, 'data_len' (16 bit) and 'pkt_len' > (32 bit) may > - * be used interchangably. > - * > - * On the datapath, it is expected that the size of packets > - * (and thus 'v') will always be <= UINT16_MAX; this means that > there is no > - * loss of accuracy in assigning 'v' to 'data_len'. > - */ > - b->mbuf.data_len = (uint16_t)v; /* Current seg length. */ > - b->mbuf.pkt_len = v; /* Total length of all segments > linked to > - * this segment. */ > + if (b->source == DPBUF_DPDK) { > + struct rte_mbuf *mbuf = &b->mbuf; > + struct rte_mbuf *fmbuf = mbuf; > + uint16_t new_len = v; > + uint16_t data_len; > + uint16_t nb_segs = 0; > + uint16_t pkt_len = 0; > + > + /* Trim 'v' length bytes from the end of the chained buffers, > freeing > + any buffers that may be left floating */ > + while (mbuf) { > + data_len = MIN(new_len, mbuf->data_len); > + mbuf->data_len = data_len; > + > + if (new_len - data_len <= 0) { > + /* Free the rest of chained mbufs */ > + free_dpdk_buf(CONTAINER_OF(mbuf->next, struct > dp_packet, > + mbuf)); > + mbuf->next = NULL; > + } else if (!mbuf->next) { > + /* Don't assign more than what we have available */ > + mbuf->data_len = MIN(new_len, > + mbuf->buf_len - mbuf->data_off); > + } > + > + new_len -= data_len; > + nb_segs += 1; > + pkt_len += mbuf->data_len; > + mbuf = mbuf->next; > + } > + > + fmbuf->nb_segs = nb_segs; > + fmbuf->pkt_len = pkt_len; Guess we do not need the extra variable, we can just do b->mbuf.pkt_len etc as below. Looks like a left over from the previous revision? In the increase packet size case we can end up with an b->mbuf.pkt_len < v, maybe we should assert on this? > + } else { > + b->mbuf.data_len = v; > + /* Total length of all segments linked to this segment. */ > + b->mbuf.pkt_len = v; > + } > } > > static inline uint16_t > @@ -451,7 +478,23 @@ __packet_data(const struct dp_packet *b) > static inline void > __packet_set_data(struct dp_packet *b, uint16_t v) > { > - b->mbuf.data_off = v; > + if (b->source == DPBUF_DPDK) { > + uint16_t prev_ofs = b->mbuf.data_off; > + b->mbuf.data_off = v; > + int16_t ofs_diff = prev_ofs - b->mbuf.data_off; > + > + /* When dealing with DPDK mbufs, keep data_off and data_len > in sync. > + * Thus, update data_len if the length changes with the move > of > + * data_off. However, if data_len is 0, there's no data to > move and > + * data_Len should remain 0. */ > + What if the data offset moves to the second buffer? This would probably never happen as all APIs assume a single address space (and they seem to calculate the offset like this), but an assert might help to avoid problems in the future. > + if (b->mbuf.data_len != 0) { > + b->mbuf.data_len = MIN(b->mbuf.data_len + ofs_diff, > + b->mbuf.buf_len - > b->mbuf.data_off); > + } > + } else { > + b->mbuf.data_off = v; > + } > } > > static inline uint16_t > -- > 2.7.4
On 03/07/2018 11:22, Eelco Chaudron wrote: > > > On 28 Jun 2018, at 17:41, Tiago Lam wrote: > >> When a dp_packet is from a DPDK source, and it contains multi-segment >> mbufs, the data_len is not equal to the packet size, pkt_len. Instead, >> the data_len of each mbuf in the chain should be considered while >> distributing the new (provided) size. >> >> To account for the above dp_packet_set_size() has been changed so >> that, >> in the multi-segment mbufs case, only the data_len on the last mbuf of >> the chain and the total size of the packet, pkt_len, are changed. The >> data_len on the intermediate mbufs preceeding the last mbuf is not >> changed by dp_packet_set_size(). Furthermore, in some cases >> dp_packet_set_size() may be used to set a smaller size than the >> current >> packet size, thus effectively trimming the end of the packet. In the >> multi-segment mbufs case this may lead to lingering mbufs that may >> need >> freeing. >> >> __dp_packet_set_data() now also updates an mbufs' data_len after >> setting >> the data offset. This is so that both fields are always in sync for >> each >> mbuf in a chain. >> >> Co-authored-by: Michael Qiu <qiudayu@chinac.com> >> Co-authored-by: Mark Kavanagh <mark.b.kavanagh@intel.com> >> Co-authored-by: Przemyslaw Lal <przemyslawx.lal@intel.com> >> Co-authored-by: Marcin Ksiadz <mksiadz@gmail.com> >> Co-authored-by: Yuanhan Liu <yliu@fridaylinux.org> >> >> Signed-off-by: Michael Qiu <qiudayu@chinac.com> >> Signed-off-by: Mark Kavanagh <mark.b.kavanagh@intel.com> >> Signed-off-by: Przemyslaw Lal <przemyslawx.lal@intel.com> >> Signed-off-by: Marcin Ksiadz <mksiadz@gmail.com> >> Signed-off-by: Yuanhan Liu <yliu@fridaylinux.org> >> Signed-off-by: Tiago Lam <tiago.lam@intel.com> >> --- >> lib/dp-packet.h | 67 >> ++++++++++++++++++++++++++++++++++++++++++++++----------- >> 1 file changed, 55 insertions(+), 12 deletions(-) >> >> diff --git a/lib/dp-packet.h b/lib/dp-packet.h >> index c612ad4..d8cd35c 100644 >> --- a/lib/dp-packet.h >> +++ b/lib/dp-packet.h >> @@ -429,17 +429,44 @@ dp_packet_size(const struct dp_packet *b) >> static inline void >> dp_packet_set_size(struct dp_packet *b, uint32_t v) >> { >> - /* netdev-dpdk does not currently support segmentation; >> consequently, for >> - * all intents and purposes, 'data_len' (16 bit) and 'pkt_len' >> (32 bit) may >> - * be used interchangably. >> - * >> - * On the datapath, it is expected that the size of packets >> - * (and thus 'v') will always be <= UINT16_MAX; this means that >> there is no >> - * loss of accuracy in assigning 'v' to 'data_len'. >> - */ >> - b->mbuf.data_len = (uint16_t)v; /* Current seg length. */ >> - b->mbuf.pkt_len = v; /* Total length of all segments >> linked to >> - * this segment. */ >> + if (b->source == DPBUF_DPDK) { >> + struct rte_mbuf *mbuf = &b->mbuf; >> + struct rte_mbuf *fmbuf = mbuf; >> + uint16_t new_len = v; >> + uint16_t data_len; >> + uint16_t nb_segs = 0; >> + uint16_t pkt_len = 0; >> + >> + /* Trim 'v' length bytes from the end of the chained buffers, >> freeing >> + any buffers that may be left floating */ >> + while (mbuf) { >> + data_len = MIN(new_len, mbuf->data_len); >> + mbuf->data_len = data_len; >> + >> + if (new_len - data_len <= 0) { >> + /* Free the rest of chained mbufs */ >> + free_dpdk_buf(CONTAINER_OF(mbuf->next, struct >> dp_packet, >> + mbuf)); >> + mbuf->next = NULL; >> + } else if (!mbuf->next) { >> + /* Don't assign more than what we have available */ >> + mbuf->data_len = MIN(new_len, >> + mbuf->buf_len - mbuf->data_off); >> + } >> + >> + new_len -= data_len; >> + nb_segs += 1; >> + pkt_len += mbuf->data_len; >> + mbuf = mbuf->next; >> + } >> + >> + fmbuf->nb_segs = nb_segs; >> + fmbuf->pkt_len = pkt_len; > > Guess we do not need the extra variable, we can just do b->mbuf.pkt_len > etc as below. Looks like a left over from the previous revision? > Good point, I got rid of it for v2. > In the increase packet size case we can end up with an b->mbuf.pkt_len < > v, maybe we should assert on this? > Yeah, it can happen if 'v' is bigger than the available tailroom. An assertion sounds good in this case since dp_packet_set_size() relies on the caller making sure there is enough space for performing the operation (like allocating space themselves if not enough space is available). >> + } else { >> + b->mbuf.data_len = v; >> + /* Total length of all segments linked to this segment. */ >> + b->mbuf.pkt_len = v; >> + } >> } >> >> static inline uint16_t >> @@ -451,7 +478,23 @@ __packet_data(const struct dp_packet *b) >> static inline void >> __packet_set_data(struct dp_packet *b, uint16_t v) >> { >> - b->mbuf.data_off = v; >> + if (b->source == DPBUF_DPDK) { >> + uint16_t prev_ofs = b->mbuf.data_off; >> + b->mbuf.data_off = v; >> + int16_t ofs_diff = prev_ofs - b->mbuf.data_off; >> + >> + /* When dealing with DPDK mbufs, keep data_off and data_len >> in sync. >> + * Thus, update data_len if the length changes with the move >> of >> + * data_off. However, if data_len is 0, there's no data to >> move and >> + * data_Len should remain 0. */ >> + > > What if the data offset moves to the second buffer? This would probably > never happen as all APIs assume a single address space (and they seem to > calculate the offset like this), but an assert might help to avoid > problems in the future. > I'll use one here as well then, for the same reasons pointed out above. Thanks for putting the time for reviewing the series, Eelco. Tiago. >> + if (b->mbuf.data_len != 0) { >> + b->mbuf.data_len = MIN(b->mbuf.data_len + ofs_diff, >> + b->mbuf.buf_len - >> b->mbuf.data_off); >> + } >> + } else { >> + b->mbuf.data_off = v; >> + } >> } >> >> static inline uint16_t >> -- >> 2.7.4
diff --git a/lib/dp-packet.h b/lib/dp-packet.h index c612ad4..d8cd35c 100644 --- a/lib/dp-packet.h +++ b/lib/dp-packet.h @@ -429,17 +429,44 @@ dp_packet_size(const struct dp_packet *b) static inline void dp_packet_set_size(struct dp_packet *b, uint32_t v) { - /* netdev-dpdk does not currently support segmentation; consequently, for - * all intents and purposes, 'data_len' (16 bit) and 'pkt_len' (32 bit) may - * be used interchangably. - * - * On the datapath, it is expected that the size of packets - * (and thus 'v') will always be <= UINT16_MAX; this means that there is no - * loss of accuracy in assigning 'v' to 'data_len'. - */ - b->mbuf.data_len = (uint16_t)v; /* Current seg length. */ - b->mbuf.pkt_len = v; /* Total length of all segments linked to - * this segment. */ + if (b->source == DPBUF_DPDK) { + struct rte_mbuf *mbuf = &b->mbuf; + struct rte_mbuf *fmbuf = mbuf; + uint16_t new_len = v; + uint16_t data_len; + uint16_t nb_segs = 0; + uint16_t pkt_len = 0; + + /* Trim 'v' length bytes from the end of the chained buffers, freeing + any buffers that may be left floating */ + while (mbuf) { + data_len = MIN(new_len, mbuf->data_len); + mbuf->data_len = data_len; + + if (new_len - data_len <= 0) { + /* Free the rest of chained mbufs */ + free_dpdk_buf(CONTAINER_OF(mbuf->next, struct dp_packet, + mbuf)); + mbuf->next = NULL; + } else if (!mbuf->next) { + /* Don't assign more than what we have available */ + mbuf->data_len = MIN(new_len, + mbuf->buf_len - mbuf->data_off); + } + + new_len -= data_len; + nb_segs += 1; + pkt_len += mbuf->data_len; + mbuf = mbuf->next; + } + + fmbuf->nb_segs = nb_segs; + fmbuf->pkt_len = pkt_len; + } else { + b->mbuf.data_len = v; + /* Total length of all segments linked to this segment. */ + b->mbuf.pkt_len = v; + } } static inline uint16_t @@ -451,7 +478,23 @@ __packet_data(const struct dp_packet *b) static inline void __packet_set_data(struct dp_packet *b, uint16_t v) { - b->mbuf.data_off = v; + if (b->source == DPBUF_DPDK) { + uint16_t prev_ofs = b->mbuf.data_off; + b->mbuf.data_off = v; + int16_t ofs_diff = prev_ofs - b->mbuf.data_off; + + /* When dealing with DPDK mbufs, keep data_off and data_len in sync. + * Thus, update data_len if the length changes with the move of + * data_off. However, if data_len is 0, there's no data to move and + * data_Len should remain 0. */ + + if (b->mbuf.data_len != 0) { + b->mbuf.data_len = MIN(b->mbuf.data_len + ofs_diff, + b->mbuf.buf_len - b->mbuf.data_off); + } + } else { + b->mbuf.data_off = v; + } } static inline uint16_t