Message ID | 1528734090-220990-6-git-send-email-tiago.lam@intel.com |
---|---|
State | Superseded |
Headers | show |
Series | Support multi-segment mbufs | expand |
On 11 Jun 2018, at 18:21, 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 | 56 > +++++++++++++++++++++++++++++++++++++++++++++----------- > 1 file changed, 45 insertions(+), 11 deletions(-) > > diff --git a/lib/dp-packet.h b/lib/dp-packet.h > index 4c104b6..c301ed5 100644 > --- a/lib/dp-packet.h > +++ b/lib/dp-packet.h > @@ -429,17 +429,39 @@ 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) { This function does not have any check to guarantee that the size set is valid? i.e. is this not a trim only function? If we increase the size, no additional mbufs get allocated (see below) > + struct rte_mbuf *seg = &b->mbuf; > + struct rte_mbuf *fmbuf = seg; > + uint16_t pkt_len = v; > + uint16_t seg_len; > + uint16_t nb_segs = 0; > + > + /* Trim 'v' length bytes from the end of the chained buffers, > freeing > + any buffers that may be left floating */ > + while (seg) { > + seg_len = MIN(pkt_len, seg->data_len); > + seg->data_len = seg_len; > + > + pkt_len -= seg_len; > + if (pkt_len <= 0) { > + /* Free the rest of chained mbufs */ > + free_dpdk_buf((struct dp_packet *) seg->next); > + seg->next = NULL; > + } else if (!seg->next) { > + seg->data_len = pkt_len; Here we could potentially set the size of the segment larger than the allocated/available buffer. Also if this is fine, we set it to the wrong value... Assume we have a single buffer of 100 bytes and we call with v=400. This will result in data_len being 300, and not 400, should probably be =pkt_len + seg_len > + } > + > + nb_segs += 1; > + seg = seg->next; > + } > + > + fmbuf->nb_segs = nb_segs; > + } 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 +473,19 @@ __packet_data(const struct dp_packet *b) > static inline void > __packet_set_data(struct dp_packet *b, uint16_t v) > { > + 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); > + } > } > > static inline uint16_t > -- > 2.7.4
On 18/06/2018 12:39, Eelco Chaudron wrote: > > > On 11 Jun 2018, at 18:21, 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 | 56 >> +++++++++++++++++++++++++++++++++++++++++++++----------- >> 1 file changed, 45 insertions(+), 11 deletions(-) >> >> diff --git a/lib/dp-packet.h b/lib/dp-packet.h >> index 4c104b6..c301ed5 100644 >> --- a/lib/dp-packet.h >> +++ b/lib/dp-packet.h >> @@ -429,17 +429,39 @@ 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) { > > This function does not have any check to guarantee that the size set is > valid? i.e. is this not a trim only function? If we increase the size, > no additional mbufs get allocated (see below) Indeed, it should be used as a trim function. If the size is increased then the expectation is that enough space has been allocated. This is the current behavior when using `DPBUF_MALLOC` dp_packets as well, and is kept here for `DPBUF_DPDK` dp_packets. > >> + struct rte_mbuf *seg = &b->mbuf; >> + struct rte_mbuf *fmbuf = seg; >> + uint16_t pkt_len = v; >> + uint16_t seg_len; >> + uint16_t nb_segs = 0; >> + >> + /* Trim 'v' length bytes from the end of the chained buffers, >> freeing >> + any buffers that may be left floating */ >> + while (seg) { >> + seg_len = MIN(pkt_len, seg->data_len); >> + seg->data_len = seg_len; >> + >> + pkt_len -= seg_len; >> + if (pkt_len <= 0) { >> + /* Free the rest of chained mbufs */ >> + free_dpdk_buf((struct dp_packet *) seg->next); >> + seg->next = NULL; >> + } else if (!seg->next) { >> + seg->data_len = pkt_len; > Here we could potentially set the size of the segment larger than the > allocated/available buffer. > > Also if this is fine, we set it to the wrong value... Assume we have a > single buffer of 100 bytes and we call with v=400. This will result in > data_len being 300, and not 400, should probably be =pkt_len + seg_len > Thanks for pointing that out. I've overlooked this, which together with the leftover in patch 07/13 made it work correctly. Tiago.
On 22 Jun 2018, at 21:04, Lam, Tiago wrote: > On 18/06/2018 12:39, Eelco Chaudron wrote: >> >> >> On 11 Jun 2018, at 18:21, 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 | 56 >>> +++++++++++++++++++++++++++++++++++++++++++++----------- >>> 1 file changed, 45 insertions(+), 11 deletions(-) >>> >>> diff --git a/lib/dp-packet.h b/lib/dp-packet.h >>> index 4c104b6..c301ed5 100644 >>> --- a/lib/dp-packet.h >>> +++ b/lib/dp-packet.h >>> @@ -429,17 +429,39 @@ 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) { >> >> This function does not have any check to guarantee that the size set is >> valid? i.e. is this not a trim only function? If we increase the size, >> no additional mbufs get allocated (see below) > > Indeed, it should be used as a trim function. If the size is increased > then the expectation is that enough space has been allocated. This is > the current behavior when using `DPBUF_MALLOC` dp_packets as well, and > is kept here for `DPBUF_DPDK` dp_packets. I think a check is still needed as it’s not only used as a trim function. For example: dp_packet_put_uninit() >> >>> + struct rte_mbuf *seg = &b->mbuf; >>> + struct rte_mbuf *fmbuf = seg; >>> + uint16_t pkt_len = v; >>> + uint16_t seg_len; >>> + uint16_t nb_segs = 0; >>> + >>> + /* Trim 'v' length bytes from the end of the chained buffers, >>> freeing >>> + any buffers that may be left floating */ >>> + while (seg) { >>> + seg_len = MIN(pkt_len, seg->data_len); >>> + seg->data_len = seg_len; >>> + >>> + pkt_len -= seg_len; >>> + if (pkt_len <= 0) { >>> + /* Free the rest of chained mbufs */ >>> + free_dpdk_buf((struct dp_packet *) seg->next); >>> + seg->next = NULL; >>> + } else if (!seg->next) { >>> + seg->data_len = pkt_len; >> Here we could potentially set the size of the segment larger than the >> allocated/available buffer. >> >> Also if this is fine, we set it to the wrong value... Assume we have a >> single buffer of 100 bytes and we call with v=400. This will result in >> data_len being 300, and not 400, should probably be =pkt_len + seg_len >> > > Thanks for pointing that out. I've overlooked this, which together with > the leftover in patch 07/13 made it work correctly.
diff --git a/lib/dp-packet.h b/lib/dp-packet.h index 4c104b6..c301ed5 100644 --- a/lib/dp-packet.h +++ b/lib/dp-packet.h @@ -429,17 +429,39 @@ 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 *seg = &b->mbuf; + struct rte_mbuf *fmbuf = seg; + uint16_t pkt_len = v; + uint16_t seg_len; + uint16_t nb_segs = 0; + + /* Trim 'v' length bytes from the end of the chained buffers, freeing + any buffers that may be left floating */ + while (seg) { + seg_len = MIN(pkt_len, seg->data_len); + seg->data_len = seg_len; + + pkt_len -= seg_len; + if (pkt_len <= 0) { + /* Free the rest of chained mbufs */ + free_dpdk_buf((struct dp_packet *) seg->next); + seg->next = NULL; + } else if (!seg->next) { + seg->data_len = pkt_len; + } + + nb_segs += 1; + seg = seg->next; + } + + fmbuf->nb_segs = nb_segs; + } 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 +473,19 @@ __packet_data(const struct dp_packet *b) static inline void __packet_set_data(struct dp_packet *b, uint16_t v) { + 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); + } } static inline uint16_t