> -----Original Message-----
> From: Vlad Zolotarov [mailto:vladz at cloudius-systems.com]
> Sent: Tuesday, March 10, 2015 9:36 PM
> To: Ananyev, Konstantin; dev at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v6 3/3] ixgbe: Add LRO support
>
>
>
> On 03/10/15 22:09, Ananyev, Konstantin wrote:
> >>> Hi Vlad,
> >>>
> >>>> -----Original Message-----
> >>>> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Vlad Zolotarov
> >>>> Sent: Monday, March 09, 2015 7:07 PM
> >>>> To: dev at dpdk.org
> >>>> Subject: [dpdk-dev] [PATCH v6 3/3] ixgbe: Add LRO support
> >>>>
> >>>> - Only x540 and 82599 devices support LRO.
> >>>> - Add the appropriate HW configuration.
> >>>> - Add RSC aware rx_pkt_burst() handlers:
> >>>> - Implemented bulk allocation and non-bulk allocation versions.
> >>>> - Add LRO-specific fields to rte_eth_rxmode, to rte_eth_dev_data
> >>>> and to igb_rx_queue.
> >>>> - Use the appropriate handler when LRO is requested.
> >>>>
> >>>> Signed-off-by: Vlad Zolotarov <vladz at cloudius-systems.com>
> >>>> ---
> >>>> New in v5:
> >>>> - Put the RTE_ETHDEV_HAS_LRO_SUPPORT definition at the beginning of
> >>>> rte_ethdev.h.
> >>>> - Removed the "TODO: Remove me" comment near
> >>>> RTE_ETHDEV_HAS_LRO_SUPPORT.
> >>>>
> >>>> New in v4:
> >>>> - Define RTE_ETHDEV_HAS_LRO_SUPPORT in rte_ethdev.h instead of
> >>>> RTE_ETHDEV_LRO_SUPPORT defined in config/common_linuxapp.
> >>>>
> >>>> New in v2:
> >>>> - Removed rte_eth_dev_data.lro_bulk_alloc.
> >>>> - Fixed a few styling and spelling issues.
> >>>> ---
> >>>> lib/librte_ether/rte_ethdev.h | 9 +-
> >>>> lib/librte_pmd_ixgbe/ixgbe_ethdev.c | 6 +
> >>>> lib/librte_pmd_ixgbe/ixgbe_ethdev.h | 5 +
> >>>> lib/librte_pmd_ixgbe/ixgbe_rxtx.c | 562
> >>>> +++++++++++++++++++++++++++++++++++-
> >>>> lib/librte_pmd_ixgbe/ixgbe_rxtx.h | 6 +
> >>>> 5 files changed, 581 insertions(+), 7 deletions(-)
> >>>>
> >>>> diff --git a/lib/librte_ether/rte_ethdev.h
> >>>> b/lib/librte_ether/rte_ethdev.h
> >>>> index 8db3127..44f081f 100644
> >>>> --- a/lib/librte_ether/rte_ethdev.h
> >>>> +++ b/lib/librte_ether/rte_ethdev.h
> >>>> @@ -172,6 +172,9 @@ extern "C" {
> >>>>
> >>>> #include <stdint.h>
> >>>>
> >>>> +/* Use this macro to check if LRO API is supported */
> >>>> +#define RTE_ETHDEV_HAS_LRO_SUPPORT
> >>>> +
> >>>> #include <rte_log.h>
> >>>> #include <rte_interrupts.h>
> >>>> #include <rte_pci.h>
> >>>> @@ -320,14 +323,15 @@ struct rte_eth_rxmode {
> >>>> enum rte_eth_rx_mq_mode mq_mode;
> >>>> uint32_t max_rx_pkt_len; /**< Only used if jumbo_frame
> >>>> enabled. */
> >>>> uint16_t split_hdr_size; /**< hdr buf size (header_split
> >>>> enabled).*/
> >>>> - uint8_t header_split : 1, /**< Header Split enable. */
> >>>> + uint16_t header_split : 1, /**< Header Split enable. */
> >>>> hw_ip_checksum : 1, /**< IP/UDP/TCP checksum offload
> >>>> enable. */
> >>>> hw_vlan_filter : 1, /**< VLAN filter enable. */
> >>>> hw_vlan_strip : 1, /**< VLAN strip enable. */
> >>>> hw_vlan_extend : 1, /**< Extended VLAN enable. */
> >>>> jumbo_frame : 1, /**< Jumbo Frame Receipt enable.
> >>>> */
> >>>> hw_strip_crc : 1, /**< Enable CRC stripping by
> >>>> hardware. */
> >>>> - enable_scatter : 1; /**< Enable scatter packets rx
> >>>> handler */
> >>>> + enable_scatter : 1, /**< Enable scatter packets rx
> >>>> handler */
> >>>> + enable_lro : 1; /**< Enable LRO */
> >>>> };
> >>>>
> >>>> /**
> >>>> @@ -1515,6 +1519,7 @@ struct rte_eth_dev_data {
> >>>> uint8_t port_id; /**< Device [external] port
> >>>> identifier. */
> >>>> uint8_t promiscuous : 1, /**< RX promiscuous mode ON(1) /
> >>>> OFF(0). */
> >>>> scattered_rx : 1, /**< RX of scattered packets is
> >>>> ON(1) / OFF(0) */
> >>>> + lro : 1, /**< RX LRO is ON(1) / OFF(0) */
> >>>> all_multicast : 1, /**< RX all multicast mode ON(1) /
> >>>> OFF(0). */
> >>>> dev_started : 1; /**< Device state: STARTED(1) /
> >>>> STOPPED(0). */
> >>>> };
> >>>> diff --git a/lib/librte_pmd_ixgbe/ixgbe_ethdev.c
> >>>> b/lib/librte_pmd_ixgbe/ixgbe_ethdev.c
> >>>> index 9d3de1a..765174d 100644
> >>>> --- a/lib/librte_pmd_ixgbe/ixgbe_ethdev.c
> >>>> +++ b/lib/librte_pmd_ixgbe/ixgbe_ethdev.c
> >>>> @@ -1648,6 +1648,7 @@ ixgbe_dev_stop(struct rte_eth_dev *dev)
> >>>>
> >>>> /* Clear stored conf */
> >>>> dev->data->scattered_rx = 0;
> >>>> + dev->data->lro = 0;
> >>>> hw->rx_bulk_alloc_allowed = false;
> >>>> hw->rx_vec_allowed = false;
> >>>>
> >>>> @@ -2018,6 +2019,11 @@ ixgbe_dev_info_get(struct rte_eth_dev *dev,
> >>>> struct rte_eth_dev_info *dev_info)
> >>>> DEV_RX_OFFLOAD_IPV4_CKSUM |
> >>>> DEV_RX_OFFLOAD_UDP_CKSUM |
> >>>> DEV_RX_OFFLOAD_TCP_CKSUM;
> >>>> +
> >>>> + if (hw->mac.type == ixgbe_mac_82599EB ||
> >>>> + hw->mac.type == ixgbe_mac_X540)
> >>>> + dev_info->rx_offload_capa |= DEV_RX_OFFLOAD_TCP_LRO;
> >>>> +
> >>>> dev_info->tx_offload_capa =
> >>>> DEV_TX_OFFLOAD_VLAN_INSERT |
> >>>> DEV_TX_OFFLOAD_IPV4_CKSUM |
> >>>> diff --git a/lib/librte_pmd_ixgbe/ixgbe_ethdev.h
> >>>> b/lib/librte_pmd_ixgbe/ixgbe_ethdev.h
> >>>> index a549f5c..e206584 100644
> >>>> --- a/lib/librte_pmd_ixgbe/ixgbe_ethdev.h
> >>>> +++ b/lib/librte_pmd_ixgbe/ixgbe_ethdev.h
> >>>> @@ -349,6 +349,11 @@ uint16_t ixgbe_recv_pkts_bulk_alloc(void *rx_queue,
> >>>> struct rte_mbuf **rx_pkts,
> >>>> uint16_t ixgbe_recv_scattered_pkts(void *rx_queue,
> >>>> struct rte_mbuf **rx_pkts, uint16_t nb_pkts);
> >>>>
> >>>> +uint16_t ixgbe_recv_pkts_lro(void *rx_queue,
> >>>> + struct rte_mbuf **rx_pkts, uint16_t nb_pkts);
> >>>> +uint16_t ixgbe_recv_pkts_lro_bulk_alloc(void *rx_queue,
> >>>> + struct rte_mbuf **rx_pkts, uint16_t nb_pkts);
> >>>> +
> >>>> uint16_t ixgbe_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
> >>>> uint16_t nb_pkts);
> >>>>
> >>>> diff --git a/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> >>>> b/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> >>>> index 58e619b..944c662 100644
> >>>> --- a/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> >>>> +++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> >>>> @@ -1366,6 +1366,15 @@ ixgbe_recv_pkts(void *rx_queue, struct rte_mbuf
> >>>> **rx_pkts,
> >>>> }
> >>>>
> >>>> /**
> >>>> + * Detect an RSC descriptor.
> >>>> + */
> >>>> +static inline uint32_t ixgbe_rsc_count(union ixgbe_adv_rx_desc *rx)
> >>>> +{
> >>>> + return (rte_le_to_cpu_32(rx->wb.lower.lo_dword.data) &
> >>>> + IXGBE_RXDADV_RSCCNT_MASK) >> IXGBE_RXDADV_RSCCNT_SHIFT;
> >>>> +}
> >>>> +
> >>>> +/**
> >>>> * Initialize the first mbuf of the returned packet:
> >>>> * - RX port identifier,
> >>>> * - hardware offload data, if any:
> >>>> @@ -1410,6 +1419,291 @@ static inline void ixgbe_fill_cluster_head_buf(
> >>>> }
> >>>> }
> >>>>
> >>>> +/**
> >>>> + * Bulk receive handler for and LRO case.
> >>>> + *
> >>>> + * @rx_queue Rx queue handle
> >>>> + * @rx_pkts table of received packets
> >>>> + * @nb_pkts size of rx_pkts table
> >>>> + * @bulk_alloc if TRUE bulk allocation is used for a HW ring refilling
> >>>> + *
> >>>> + * Handles the Rx HW ring completions when RSC feature is configured.
> >>>> Uses an
> >>>> + * additional ring of igb_rsc_entry's that will hold the relevant RSC
> >>>> info.
> >>>> + *
> >>>> + * We use the same logic as in Lunux and in FreeBSD ixgbe drivers:
> >>>> + * 1) When non-EOP RSC completion arrives:
> >>>> + * a) Update the HEAD of the current RSC aggregation cluster with
> >>>> the new
> >>>> + * segment's data length.
> >>>> + * b) Set the "next" pointer of the current segment to point to the
> >>>> segment
> >>>> + * at the NEXTP index.
> >>>> + * c) Pass the HEAD of RSC aggregation cluster on to the next NEXTP
> >>>> entry
> >>>> + * in the sw_rsc_ring.
> >>>> + * 2) When EOP arrives we just update the cluster's total length and
> >>>> offload
> >>>> + * flags and deliver the cluster up to the upper layers. In our case
> >>>> - put it
> >>>> + * in the rx_pkts table.
> >>>> + *
> >>>> + * Returns the number of received packets/clusters (according to the
> >>>> "bulk
> >>>> + * receive" interface).
> >>>> + */
> >>>> +static inline uint16_t
> >>>> +_recv_pkts_lro(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t
> >>>> nb_pkts,
> >>>> + bool bulk_alloc)
> >>>> +{
> >>>> + struct igb_rx_queue *rxq = rx_queue;
> >>>> + volatile union ixgbe_adv_rx_desc *rx_ring = rxq->rx_ring;
> >>>> + struct igb_rx_entry *sw_ring = rxq->sw_ring;
> >>>> + struct igb_rsc_entry *sw_rsc_ring = rxq->sw_rsc_ring;
> >>>> + uint16_t rx_id = rxq->rx_tail;
> >>>> + uint16_t nb_rx = 0;
> >>>> + uint16_t nb_hold = rxq->nb_rx_hold;
> >>>> + uint16_t prev_id = rxq->rx_tail;
> >>>> +
> >>>> + while (nb_rx < nb_pkts) {
> >>>> + bool eop;
> >>>> + struct igb_rx_entry *rxe;
> >>>> + struct igb_rsc_entry *rsc_entry;
> >>>> + struct igb_rsc_entry *next_rsc_entry;
> >>>> + struct igb_rx_entry *next_rxe;
> >>>> + struct rte_mbuf *first_seg;
> >>>> + struct rte_mbuf *rxm;
> >>>> + struct rte_mbuf *nmb;
> >>>> + union ixgbe_adv_rx_desc rxd;
> >>>> + uint16_t data_len;
> >>>> + uint16_t next_id;
> >>>> + volatile union ixgbe_adv_rx_desc *rxdp;
> >>>> + uint32_t staterr;
> >>>> +
> >>>> +next_desc:
> >>>> + /*
> >>>> + * The code in this whole file uses the volatile
> >>>> pointer to
> >>>> + * ensure the read ordering of the status and the rest
> >>>> of the
> >>>> + * descriptor fields (on the compiler level only!!!).
> >>>> This is so
> >>>> + * UGLY - why not to just use the compiler barrier
> >>>> instead? DPDK
> >>>> + * even has the rte_compiler_barrier() for that.
> >>>> + *
> >>>> + * But most importantly this is just wrong because this
> >>>> doesn't
> >>>> + * ensure memory ordering in a general case at all. For
> >>>> + * instance, DPDK is supposed to work on Power CPUs
> >>>> where
> >>>> + * compiler barrier may just not be enough!
> >>>> + *
> >>>> + * I tried to write only this function properly to have
> >>>> a
> >>>> + * starting point (as a part of an LRO/RSC series) but
> >>>> the
> >>>> + * compiler cursed at me when I tried to cast away the
> >>>> + * "volatile" from rx_ring (yes, it's volatile too!!!).
> >>>> So, I'm
> >>>> + * keeping it the way it is for now.
> >>>> + *
> >>>> + * The code in this file is broken in so many other
> >>>> places and
> >>>> + * will just not work on a big endian CPU anyway
> >>>> therefore the
> >>>> + * lines below will have to be revisited together with
> >>>> the rest
> >>>> + * of the ixgbe PMD.
> >>>> + *
> >>>> + * TODO:
> >>>> + * - Get rid of "volatile" crap and let the compiler
> >>>> do its
> >>>> + * job.
> >>>> + * - Use the proper memory barrier (rte_rmb()) to
> >>>> ensure the
> >>>> + * memory ordering below.
> >>> Ok, so you wanted to put rte_rmb(), straight after:
> >>> staterr = rte_le_to_cpu_32(rxdp->wb.upper.status_error);
> >>> correct?
> >>> I agree that for machines with relaxed memory model (PPC) we do need it
> >>> here.
> >>> So why not just put it there, instead of complaining about in in
> >>> comments? ;)
> >> Because it's not a proper fix and I don't like workarounds.
> > Why not? For machines with relaxed memory model you would need rmb() here
> > no matter does rxdp points to volatile or not.
> >
> >>> About rxdp being pointer to volatile, why it bothers you that much?
> >> Because using of "volatile" prevent the compiler from optimizing every
> >> code piece where the "volatile" variable is participating and that's a
> >> shame.
> >> Read this
> >> https://www.kernel.org/doc/Documentation/volatile-considered-harmful.txt
> >> for a more detailed explanation.
> >>
> >>> You copy the whole RXD to the local variable anyway, and then reference
> >>> it only to setup new addresses.
> >> The fact that we have to copy the whole descriptor while we may not need
> >> all the data from it at the end is one problem.
> > I understand that, but I don't think that the difference would that
> > critical.
> > Though I don't have any data in hand to compare.
> >
> >> The proper solution in Rx ring context should go as follows:
> >>
> >> 1. Remove the "volatile" qualifier from rx_ring (HW Rx descriptors ring).
> >> 2. Remove "volatile" at all places where rx_ring is accessed.
> >> 3. Adjust the code in (2):
> >> 1. Remove the descriptor copy u've mentioned and access the
> >> descriptor data directly.
> >> 2. Ensure the proper ordering by using the proper memory barriers,
> >> which are missing in the DPDK SDK at the moment (see a small
> >> discussion about this with Stephen and Avi on "[dpdk-dev]
> >> [PATCH v1 5/5] ixgbe: Add LRO support" thread).
> > I think you are mixing 2 different issues here:
> >
> > 1. For architectures with relaxed memory model we do need rmb() after that
> > line:
> > staterr = rte_le_to_cpu_32(rxdp->wb.upper.status_error);
> > We do need it *always*, not depending on is rx_ring a volatile or not.
> > If we really plan to support PPC and other architectures that allow read
> > reordering -
> > not having an 'rmb()' or similar sync primitive here is a bug.
> > Same thing applies to 'wmb()' before updating RDT.
> >
> > 2. volatile rx_ring vs non-volatile with explicit memory ordering
> > instrincts.
> > Actually I think that using volatile rx_ring is not a real bug on itself.
> > Code with volatile rx_ring and fix for #1 in place would work correctly on
> > all architectures.
> > It might be slower than non-volatile approach, but nothing would be broken.
> >
> > About the existing RX/TX functions and PPC support:
> > Note that all of them were created before PPC support for DPDK was
> > introduced.
> > At that moment only IA was supported.
> > That's why in some places where you would expect to see 'mb()' there are
> > 'volatile' and/or ' rte_compiler_barrier' instead.
> > Why all that places wasn't updated when PPC support was added - that's
> > another question.
> > From my understanding - with current implementation some of DPDK PMDs
> > RX/TX functions and rte_ring wouldn't work correctly
> on PPC.
> > So, I suppose we need to decide for ourselves - do we really want to
> > support PPC and other architectures with non-IA memory
> model or not?
> > If not, then I think we don't need any mb()s inside recv_pkts_lro() - just
> > rte_compiler_barrier seems enough, and no point to
> complain about
> > it in comments.
> > If yes - then why to introduce a new function with a known potential bug?
>
> In order to introduce a new function with the proper implementation or
> to fix any other places with the similar weakness I would need a proper
> tools like a proper platform-dependent barrier-macros similar to
> smp_Xmb() Linux macros that reduce to a compiler barrier where
> appropriate or to a proper memory fence where needed.
I understand that.
Let's add new macro for that: rte_smp_Xmb() or something,
so it would be just rte_compiler_barrier() for x86 and a proper mb() for PPC.
>
> Unfortunately DPDK doesn't have such at the moment. That's why I put a
> big fat comment at the place that has to be fixed once they are introduced.
>
> U are right though about "volatile" thing not being a bug but it would
> be strange to keep it after barriers are properly placed. That's why I
> think these 2 changes should go together.
Yep, with explicit memory ordering volatile will become redundant and could be
removed.
Though, I don't see why it should be applied separately.
>From my point: first is a bug fix, second is an enhancement.
>
> About the "decision" we have to make - I think it has been decided
> already since PPC is one the official DPDK targets. Therefore the only
> thing to decide here is when and who gets to fix these things. One thing
> is obvious - this patch is not the right place to do it. ;)
My thought was to introduce such macro(s) and start using it with that patch :)
But ok, if you feel like it's too much for that patch, let's leave it as it is
right now.
>
> >
> >> As it sounds this is going to be a VERY sensitive patchset.
> >> That's why it should go separately from this patchwork (or from any
> >> other patchwork).
> > For that patch, I am not suggesting you to change any other functions, just
> > one that you introducing.
>
> I don't think that putting an lfence on x86 there is a good idea. As
> I've just explained above - once DPDK has proper platform-dependent
> rmb() macros I'll gladly revisit these lines.
Sure, plain rte_rmb() would slowdown things a lot here.
Totally agree with you here - it should be platform dependent macro, see above.
> Frankly, the same could be
> told about the rte_wmb() before the RDT update but it is much less
> harmful than lfence so I didn't raise it... ;)
>
> >
> >>>> + */
> >>>> + rxdp = &rx_ring[rx_id];
> >>>> + staterr = rte_le_to_cpu_32(rxdp->wb.upper.status_error);
> >>>> +
> >>>> + if (!(staterr & IXGBE_RXDADV_STAT_DD))
> >>>> + break;
> >>>> +
> >>>> + rxd = *rxdp;
> >>>> +
> >>>> + PMD_RX_LOG(DEBUG, "port_id=%u queue_id=%u rx_id=%u "
> >>>> + "staterr=0x%x data_len=%u",
> >>>> + rxq->port_id, rxq->queue_id, rx_id, staterr,
> >>>> + rte_le_to_cpu_16(rxd.wb.upper.length));
> >>>> +
> >>>> + if (!bulk_alloc) {
> >>>> + nmb = rte_rxmbuf_alloc(rxq->mb_pool);
> >>>> + if (nmb == NULL) {
> >>>> + PMD_RX_LOG(DEBUG, "RX mbuf alloc failed
> >>>> "
> >>>> + "port_id=%u
> >>>> queue_id=%u",
> >>>> + rxq->port_id, rxq->queue_id);
> >>>> +
> >>>> + rte_eth_devices[rxq->port_id].data->
> >>>> +
> >>>> rx_mbuf_alloc_failed++;
> >>>> + break;
> >>>> + }
> >>>> + } else if (nb_hold > rxq->rx_free_thresh) {
> >>>> + uint16_t next_rdt = rxq->rx_free_trigger;
> >>>> +
> >>>> + if (!ixgbe_rx_alloc_bufs(rxq, false)) {
> >>>> + rte_wmb();
> >>>> + IXGBE_PCI_REG_WRITE(rxq->rdt_reg_addr,
> >>>> + next_rdt);
> >>>> + nb_hold -= rxq->rx_free_thresh;
> >>>> + } else {
> >>>> + PMD_RX_LOG(DEBUG, "RX bulk alloc failed
> >>>> "
> >>>> + "port_id=%u
> >>>> queue_id=%u",
> >>>> + rxq->port_id, rxq->queue_id);
> >>>> +
> >>>> + rte_eth_devices[rxq->port_id].data->
> >>>> +
> >>>> rx_mbuf_alloc_failed++;
> >>>> + break;
> >>>> + }
> >>>> + }
> >>>> +
> >>>> + nb_hold++;
> >>>> + rxe = &sw_ring[rx_id];
> >>>> + eop = staterr & IXGBE_RXDADV_STAT_EOP;
> >>>> +
> >>>> + next_id = rx_id + 1;
> >>>> + if (next_id == rxq->nb_rx_desc)
> >>>> + next_id = 0;
> >>>> +
> >>>> + /* Prefetch next mbuf while processing current one. */
> >>>> + rte_ixgbe_prefetch(sw_ring[next_id].mbuf);
> >>>> +
> >>>> + /*
> >>>> + * When next RX descriptor is on a cache-line boundary,
> >>>> + * prefetch the next 4 RX descriptors and the next 4
> >>>> pointers
> >>>> + * to mbufs.
> >>>> + */
> >>>> + if ((next_id & 0x3) == 0) {
> >>>> + rte_ixgbe_prefetch(&rx_ring[next_id]);
> >>>> + rte_ixgbe_prefetch(&sw_ring[next_id]);
> >>>> + }
> >>>> +
> >>>> + rxm = rxe->mbuf;
> >>>> +
> >>>> + if (!bulk_alloc) {
> >>>> + __le64 dma =
> >>>> +
> >>>> rte_cpu_to_le_64(RTE_MBUF_DATA_DMA_ADDR_DEFAULT(nmb));
> >>>> + /*
> >>>> + * Update RX descriptor with the physical
> >>>> address of the
> >>>> + * new data buffer of the new allocated mbuf.
> >>>> + */
> >>>> + rxe->mbuf = nmb;
> >>>> +
> >>>> + rxm->data_off = RTE_PKTMBUF_HEADROOM;
> >>>> + rxdp->read.hdr_addr = dma;
> >>>> + rxdp->read.pkt_addr = dma;
> >>>> + }
> >>>> + /*
> >>>> + * Set data length & data buffer address of mbuf.
> >>>> + */
> >>>> + data_len = rte_le_to_cpu_16(rxd.wb.upper.length);
> >>>> + rxm->data_len = data_len;
> >>>> +
> >>>> + if (!eop) {
> >>>> + uint16_t nextp_id;
> >>>> + /*
> >>>> + * Get next descriptor index:
> >>>> + * - For RSC it's in the NEXTP field.
> >>>> + * - For a scattered packet - it's just a
> >>>> following
> >>>> + * descriptor.
> >>>> + */
> >>>> + if (ixgbe_rsc_count(&rxd))
> >>>> + nextp_id =
> >>>> + (staterr &
> >>>> IXGBE_RXDADV_NEXTP_MASK) >>
> >>>> +
> >>>> IXGBE_RXDADV_NEXTP_SHIFT;
> >>>> + else
> >>>> + nextp_id = next_id;
> >>>> +
> >>>> + next_rsc_entry = &sw_rsc_ring[nextp_id];
> >>>> + next_rxe = &sw_ring[nextp_id];
> >>>> + rte_ixgbe_prefetch(next_rxe);
> >>>> + }
> >>>> +
> >>>> + rsc_entry = &sw_rsc_ring[rx_id];
> >>>> + first_seg = rsc_entry->fbuf;
> >>>> + rsc_entry->fbuf = NULL;
> >>>> +
> >>>> + /*
> >>>> + * If this is the first buffer of the received packet,
> >>>> + * set the pointer to the first mbuf of the packet and
> >>>> + * initialize its context.
> >>>> + * Otherwise, update the total length and the number of
> >>>> segments
> >>>> + * of the current scattered packet, and update the
> >>>> pointer to
> >>>> + * the last mbuf of the current packet.
> >>>> + */
> >>>> + if (first_seg == NULL) {
> >>>> + first_seg = rxm;
> >>>> + first_seg->pkt_len = data_len;
> >>>> + first_seg->nb_segs = 1;
> >>>> + } else {
> >>>> + first_seg->pkt_len += data_len;
> >>>> + first_seg->nb_segs++;
> >>>> + }
> >>>> +
> >>>> + prev_id = rx_id;
> >>>> + rx_id = next_id;
> >>>> +
> >>>> + /*
> >>>> + * If this is not the last buffer of the received
> >>>> packet, update
> >>>> + * the pointer to the first mbuf at the NEXTP entry in
> >>>> the
> >>>> + * sw_rsc_ring and continue to parse the RX ring.
> >>>> + */
> >>>> + if (!eop) {
> >>>> + rxm->next = next_rxe->mbuf;
> >>>> + next_rsc_entry->fbuf = first_seg;
> >>>> + goto next_desc;
> >>> So _recv_pkts_lro() can return with one of rxq->rsc_entry[i] != NULL,
> >>> correct?
> >>> If so, then I think you need at ixgbe_rx_queue_release_mbufs() to add the
> >>> code, that would go through
> >>> all rsc_entry[] to find one whose fbuf is != NULL, call
> >>> rte_pktmbuf_free() for it and reset to NULL.
> >>> To handle the case:
> >>> recv_pkts_lro(rxq, ...);
> >>> rte_eth_dev_stop();
> >>> rte_eth_dev_start();
> >>> recv_pkts_lro(rxq, ...);
> >> Right. I've missed that part.
> >>
> >>> BTW, that also means that you can't do:
> >>> rxm->next = next_rxe->mbuf;
> >>> above, and
> >>> rxm->next = NULL;
> >>> should be done before 'goto next_desc;' too
> >> Your proposal will cost cycles in the fast path on account of saving
> >> cycles in the slow path: we'll have to add another pointer to the
> >> igb_rsc_entry to hold the last mbuf in the current cluster that we'll
> >> have to read and update for every new completed RSC descriptor.
> >>
> >> The easier way would be to just reset the next-pointer of the last
> >> descriptor in the RSC cluster to NULL (according to nb_segs) before
> >> calling for rte_pktmbuf_free() in ixgbe_rx_queue_release_mbufs().
> > Should work too, I think.
>
> The final solution is even nicer - see v7. And it works like a charm
> too... ;)
Good to hear :)
>
> >
> >>>> + }
> >>>> +
> >>>> + /*
> >>>> + * This is the last buffer of the received packet -
> >>>> return
> >>>> + * the current cluster to the user.
> >>>> + */
> >>>> + rxm->next = NULL;
> >>>> +
> >>>> + /* Initialize the first mbuf of the returned packet */
> >>>> + ixgbe_fill_cluster_head_buf(first_seg, &rxd,
> >>>> rxq->port_id,
> >>>> + staterr);
> >>>> +
> >>>> + /* Prefetch data of first segment, if configured to do
> >>>> so. */
> >>>> + rte_packet_prefetch((char *)first_seg->buf_addr +
> >>>> + first_seg->data_off);
> >>>> +
> >>>> + /*
> >>>> + * Store the mbuf address into the next entry of the
> >>>> array
> >>>> + * of returned packets.
> >>>> + */
> >>>> + rx_pkts[nb_rx++] = first_seg;
> >>>> + }
> >>>> +
> >>>> + /*
> >>>> + * Record index of the next RX descriptor to probe.
> >>>> + */
> >>>> + rxq->rx_tail = rx_id;
> >>>> +
> >>>> + /*
> >>>> + * If the number of free RX descriptors is greater than the RX
> >>>> free
> >>>> + * threshold of the queue, advance the Receive Descriptor Tail
> >>>> (RDT)
> >>>> + * register.
> >>>> + * Update the RDT with the value of the last processed RX
> >>>> descriptor
> >>>> + * minus 1, to guarantee that the RDT register is never equal
> >>>> to the
> >>>> + * RDH register, which creates a "full" ring situtation from the
> >>>> + * hardware point of view...
> >>>> + */
> >>>> + if (!bulk_alloc && nb_hold > rxq->rx_free_thresh) {
> >>>> + PMD_RX_LOG(DEBUG, "port_id=%u queue_id=%u rx_tail=%u "
> >>>> + "nb_hold=%u nb_rx=%u",
> >>>> + rxq->port_id, rxq->queue_id, rx_id, nb_hold,
> >>>> nb_rx);
> >>>> +
> >>> I suppose if you do wmb() after rte_rxmbuf_alloc(), you'd better do it
> >>> here too.
> >> Right! Missed that when copied this code from
> >> ixgbe_recv_scattered_pkts()... ;) Note that the barrier is missing there
> >> too...
> >> These are the examples of the code that works on x86 only because of
> >> that "volatile" thing and will break once it's removed. On PPC it is
> >> broken even with "volatile".
> > Yep, as I said above -for IA we don't need mb() here - using 'volatile' or
> > compiler barrier seems enough to me.
> > For PPC - I think we do.
> >
> >>>> + IXGBE_PCI_REG_WRITE(rxq->rdt_reg_addr, prev_id);
> >>>> + nb_hold = 0;
> >>>> + }
> >>>> +
> >>>> + rxq->nb_rx_hold = nb_hold;
> >>>> + return nb_rx;
> >>>> +}
> >>>> +
> >>>> +uint16_t
> >>>> +ixgbe_recv_pkts_lro(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t
> >>>> nb_pkts)
> >>>> +{
> >>>> + return _recv_pkts_lro(rx_queue, rx_pkts, nb_pkts, false);
> >>>> +}
> >>>> +
> >>>> +uint16_t
> >>>> +ixgbe_recv_pkts_lro_bulk_alloc(void *rx_queue, struct rte_mbuf
> >>>> **rx_pkts,
> >>>> + uint16_t nb_pkts)
> >>>> +{
> >>>> + return _recv_pkts_lro(rx_queue, rx_pkts, nb_pkts, true);
> >>>> +}
> >>>> +
> >>>> uint16_t
> >>>> ixgbe_recv_scattered_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
> >>>> uint16_t nb_pkts)
> >>>> @@ -2024,6 +2318,7 @@ ixgbe_rx_queue_release(struct igb_rx_queue *rxq)
> >>>> if (rxq != NULL) {
> >>>> ixgbe_rx_queue_release_mbufs(rxq);
> >>>> rte_free(rxq->sw_ring);
> >>>> + rte_free(rxq->sw_rsc_ring);
> >>>> rte_free(rxq);
> >>>> }
> >>>> }
> >>>> @@ -2146,6 +2441,7 @@ ixgbe_reset_rx_queue(struct ixgbe_hw *hw, struct
> >>>> igb_rx_queue *rxq)
> >>>> rxq->nb_rx_hold = 0;
> >>>> rxq->pkt_first_seg = NULL;
> >>>> rxq->pkt_last_seg = NULL;
> >>>> + rxq->rsc_en = 0;
> >>>> }
> >>>>
> >>>> int
> >>>> @@ -2160,6 +2456,14 @@ ixgbe_dev_rx_queue_setup(struct rte_eth_dev *dev,
> >>>> struct igb_rx_queue *rxq;
> >>>> struct ixgbe_hw *hw;
> >>>> uint16_t len;
> >>>> + struct rte_eth_dev_info dev_info = { 0 };
> >>>> + struct rte_eth_rxmode *dev_rx_mode =
> >>>> &dev->data->dev_conf.rxmode;
> >>>> + bool rsc_requested = false;
> >>>> +
> >>>> + dev->dev_ops->dev_infos_get(dev, &dev_info);
> >>>> + if ((dev_info.rx_offload_capa & DEV_RX_OFFLOAD_TCP_LRO) &&
> >>>> + dev_rx_mode->enable_lro)
> >>>> + rsc_requested = true;
> >>>>
> >>>> PMD_INIT_FUNC_TRACE();
> >>>> hw = IXGBE_DEV_PRIVATE_TO_HW(dev->data->dev_private);
> >>>> @@ -2265,12 +2569,28 @@ ixgbe_dev_rx_queue_setup(struct rte_eth_dev *dev,
> >>>> rxq->sw_ring = rte_zmalloc_socket("rxq->sw_ring",
> >>>> sizeof(struct igb_rx_entry) *
> >>>> len,
> >>>> RTE_CACHE_LINE_SIZE,
> >>>> socket_id);
> >>>> - if (rxq->sw_ring == NULL) {
> >>>> + if (!rxq->sw_ring) {
> >>> Wonder what was wrong with that one? :)
> >> Nothing - just aligned it with the lines I've added below. ;)
> >>
> >>>> ixgbe_rx_queue_release(rxq);
> >>>> return (-ENOMEM);
> >>>> }
> >>>> - PMD_INIT_LOG(DEBUG, "sw_ring=%p hw_ring=%p dma_addr=0x%"PRIx64,
> >>>> - rxq->sw_ring, rxq->rx_ring,
> >>>> rxq->rx_ring_phys_addr);
> >>>> +
> >>>> + if (rsc_requested) {
> >>>> + rxq->sw_rsc_ring =
> >>>> + rte_zmalloc_socket("rxq->sw_rsc_ring",
> >>>> + sizeof(struct igb_rsc_entry)
> >>>> * len,
> >>>> + RTE_CACHE_LINE_SIZE,
> >>>> socket_id);
> >>>> + if (!rxq->sw_rsc_ring) {
> >>>> + ixgbe_rx_queue_release(rxq);
> >>>> + return (-ENOMEM);
> >>>> + }
> >>>> + } else {
> >>>> + rxq->sw_rsc_ring = NULL;
> >>>> + }
> >>>> +
> >>>> + PMD_INIT_LOG(DEBUG, "sw_ring=%p sw_rsc_ring=%p hw_ring=%p "
> >>>> + "dma_addr=0x%"PRIx64,
> >>>> + rxq->sw_ring, rxq->sw_rsc_ring, rxq->rx_ring,
> >>>> + rxq->rx_ring_phys_addr);
> >>>>
> >>>> if (!rte_is_power_of_2(nb_desc)) {
> >>>> PMD_INIT_LOG(DEBUG, "queue[%d] doesn't meet Vector Rx "
> >>>> @@ -3515,6 +3835,84 @@ ixgbe_dev_mq_tx_configure(struct rte_eth_dev *dev)
> >>>> return 0;
> >>>> }
> >>>>
> >>>> +/**
> >>>> + * get_rscctl_maxdesc - Calculate the RSCCTL[n].MAXDESC for PF
> >>>> + *
> >>>> + * Return the RSCCTL[n].MAXDESC for 82599 and x540 PF devices according
> >>>> to the
> >>>> + * spec rev. 3.0 chapter 8.2.3.8.13.
> >>>> + *
> >>>> + * @pool Memory pool of the Rx queue
> >>>> + */
> >>>> +static inline uint32_t get_rscctl_maxdesc(struct rte_mempool *pool)
> >>>> +{
> >>>> + struct rte_pktmbuf_pool_private *mp_priv =
> >>>> rte_mempool_get_priv(pool);
> >>>> +
> >>>> + /* MAXDESC * SRRCTL.BSIZEPKT must not exceed 64 KB minus one */
> >>>> + uint16_t maxdesc =
> >>>> + 65535 / (mp_priv->mbuf_data_room_size -
> >>>> RTE_PKTMBUF_HEADROOM);
> >>> A nit: use some macro (UINt16_MAX?) instead of hardcoded constant if
> >>> possible.
> >> Using UINT16_MAX here would be very confusing. The value here just like
> >> values below (16, 8, 4) are values that are explicitly stated in the
> >> RSCCTL[n].MAXDESC description in the spec and this code piece is
> >> implementing what spec is demanding. Therefore IMHO using the
> >> explicit values from the spec here is the most readable way considering
> >> the reader that will try to compare this code to the spec section
> >> mentioned above and check that the code is correct.
> > Ok, if you think UINT16_MAX is confusing, then just add a new one:
> > IXGBE_RSC_MAX_PACKET_SIZE or something.
> > As I understand, that's sort of upper limit for the RSC packet size
> > supported, right?
>
> Why to define a macro for a value that is not used anywhere else but
> here and that is never going to be changed? How does it make the code
> more readable or robust?
>
> >
> >>
> >>>> +
> >>>> + if (maxdesc >= 16)
> >>>> + return IXGBE_RSCCTL_MAXDESC_16;
> >>>> + else if (maxdesc >= 8)
> >>>> + return IXGBE_RSCCTL_MAXDESC_8;
> >>>> + else if (maxdesc >= 4)
> >>>> + return IXGBE_RSCCTL_MAXDESC_4;
> >>>> + else
> >>>> + return IXGBE_RSCCTL_MAXDESC_1;
> >>>> +}
> >>>> +
> >>>> +/* (Taken from FreeBSD tree)
> >>>> +** Setup the correct IVAR register for a particular MSIX interrupt
> >>>> +** (yes this is all very magic and confusing :)
> >>>> +** - entry is the register array entry
> >>>> +** - vector is the MSIX vector for this queue
> >>>> +** - type is RX/TX/MISC
> >>>> +*/
> >>>> +static void
> >>>> +ixgbe_set_ivar(struct rte_eth_dev *dev, u8 entry, u8 vector, s8 type)
> >>>> +{
> >>>> + struct ixgbe_hw *hw =
> >>>> IXGBE_DEV_PRIVATE_TO_HW(dev->data->dev_private);
> >>>> + u32 ivar, index;
> >>>> +
> >>>> + vector |= IXGBE_IVAR_ALLOC_VAL;
> >>>> +
> >>>> + switch (hw->mac.type) {
> >>>> +
> >>>> + case ixgbe_mac_82598EB:
> >>>> + if (type == -1)
> >>>> + entry = IXGBE_IVAR_OTHER_CAUSES_INDEX;
> >>>> + else
> >>>> + entry += (type * 64);
> >>>> + index = (entry >> 2) & 0x1F;
> >>>> + ivar = IXGBE_READ_REG(hw, IXGBE_IVAR(index));
> >>>> + ivar &= ~(0xFF << (8 * (entry & 0x3)));
> >>>> + ivar |= (vector << (8 * (entry & 0x3)));
> >>>> + IXGBE_WRITE_REG(hw, IXGBE_IVAR(index), ivar);
> >>>> + break;
> >>>> +
> >>>> + case ixgbe_mac_82599EB:
> >>>> + case ixgbe_mac_X540:
> >>>> + if (type == -1) { /* MISC IVAR */
> >>>> + index = (entry & 1) * 8;
> >>>> + ivar = IXGBE_READ_REG(hw, IXGBE_IVAR_MISC);
> >>>> + ivar &= ~(0xFF << index);
> >>>> + ivar |= (vector << index);
> >>>> + IXGBE_WRITE_REG(hw, IXGBE_IVAR_MISC, ivar);
> >>>> + } else { /* RX/TX IVARS */
> >>>> + index = (16 * (entry & 1)) + (8 * type);
> >>>> + ivar = IXGBE_READ_REG(hw, IXGBE_IVAR(entry >>
> >>>> 1));
> >>>> + ivar &= ~(0xFF << index);
> >>>> + ivar |= (vector << index);
> >>>> + IXGBE_WRITE_REG(hw, IXGBE_IVAR(entry >> 1),
> >>>> ivar);
> >>>> + }
> >>>> +
> >>>> + break;
> >>>> +
> >>>> + default:
> >>>> + break;
> >>>> + }
> >>>> +}
> >>>> +
> >>>> void set_rx_function(struct rte_eth_dev *dev)
> >>>> {
> >>>> struct ixgbe_hw *hw =
> >>>> IXGBE_DEV_PRIVATE_TO_HW(dev->data->dev_private);
> >>>> @@ -3565,6 +3963,25 @@ void set_rx_function(struct rte_eth_dev *dev)
> >>>> dev->rx_pkt_burst = ixgbe_recv_scattered_pkts;
> >>>> }
> >>>> }
> >>>> +
> >>>> + /*
> >>>> + * Initialize the appropriate LRO callback.
> >>>> + *
> >>>> + * If all queues satisfy the bulk allocation preconditions
> >>>> + * (hw->rx_bulk_alloc_allowed is TRUE) then we may use bulk
> >>>> allocation.
> >>>> + * Otherwise use a single allocation version.
> >>>> + */
> >>>> + if (dev->data->lro) {
> >>>> + if (hw->rx_bulk_alloc_allowed) {
> >>>> + PMD_INIT_LOG(INFO, "LRO is requested. Using a
> >>>> bulk "
> >>>> + "allocation version");
> >>>> + dev->rx_pkt_burst =
> >>>> ixgbe_recv_pkts_lro_bulk_alloc;
> >>>> + } else {
> >>>> + PMD_INIT_LOG(INFO, "LRO is requested. Using a
> >>>> single "
> >>>> + "allocation version");
> >>>> + dev->rx_pkt_burst = ixgbe_recv_pkts_lro;
> >>>> + }
> >>>> + }
> >>>> }
> >>> As I understand, ixgbe_recv_pkts_lro() can handle both LRO and normal
> >>> scattered packets?
> >> Not as it is now. It may be easily patched to do so though.
> >>
> >>> If that so, then can we remove ixgbe_recv_scattered_pkts() at all and use
> >>> ixgbe_recv_scattered_pkts() for both cases?
> >> This was explicitly requested from me by Bruce Richardson (see
> >> "[dpdk-dev] : ixgbe: why bulk allocation is not used for a scattered Rx
> >> flow?" thread) to separate the complicated handling from the simple high
> >> performance one. The handling in the RSC routine is more generic and
> >> thus is a bit of overkill for the simple scattered case: e.g. there is
> >> no need to a sw_rsc_ring.
> > I think Bruce meant ixgbe_recv_pkts_bulk_alloc() not
> > ixgbe_recv_scattered_pkts()
> > when he told about simple and high performance RX path.
> >
> >> Therefore I preferred to advance with small steps here. And if there
> >> will be a decision to join these flows - it may be done with a rather
> >> small patch in the future.
> > Ok, that's understandable and I wouldn't insist to do that in the same
> > patch.
> > It just worries me that number of our ixgbe RX functions keeps increasing.
>
> Let's have this series get to the master and I'll send a follow-up
> series that kills non-vector scatter callback. Agreed? ;)
Yes, as I said above, am ok with that.
>
> >
> >
> >>>> /*
> >>>> @@ -3583,10 +4000,26 @@ ixgbe_dev_rx_init(struct rte_eth_dev *dev)
> >>>> uint32_t maxfrs;
> >>>> uint32_t srrctl;
> >>>> uint32_t rdrxctl;
> >>>> + uint32_t rscctl;
> >>>> + uint32_t psrtype;
> >>>> + uint32_t rfctl;
> >>>> uint32_t rxcsum;
> >>>> uint16_t buf_size;
> >>>> uint16_t i;
> >>>> struct rte_eth_rxmode *rx_conf = &dev->data->dev_conf.rxmode;
> >>>> + struct rte_eth_dev_info dev_info = { 0 };
> >>>> + bool rsc_capable = false;
> >>>> +
> >>>> + /* Sanity check */
> >>>> + dev->dev_ops->dev_infos_get(dev, &dev_info);
> >>>> + if (dev_info.rx_offload_capa & DEV_RX_OFFLOAD_TCP_LRO)
> >>>> + rsc_capable = true;
> >>> @ 7.11.1 82599 spec says:
> >>> " Note that in SR-IOV mode the RSC must be disabled globally by setting
> >>> the RFCTL.RSC_DIS bit."
> >>> Add a check?
> >> Good catch! Will add a check. Thanks.
> >>
> >>>> +
> >>>> + if (!rsc_capable && rx_conf->enable_lro) {
> >>>> + PMD_INIT_LOG(CRIT, "LRO is requested on HW that doesn't
> >>>> "
> >>>> + "support it");
> >>>> + return -EINVAL;
> >>>> + }
> >>>>
> >>>> PMD_INIT_FUNC_TRACE();
> >>>> hw = IXGBE_DEV_PRIVATE_TO_HW(dev->data->dev_private);
> >>>> @@ -3606,13 +4039,44 @@ ixgbe_dev_rx_init(struct rte_eth_dev *dev)
> >>>> IXGBE_WRITE_REG(hw, IXGBE_FCTRL, fctrl);
> >>>>
> >>>> /*
> >>>> + * RFCTL configuration
> >>>> + *
> >>>> + * Since NFS packets coalescing is not supported - clear
> >>>> RFCTL.NFSW_DIS
> >>>> + * and RFCTL.NFSR_DIS when RSC is enabled.
> >>>> + */
> >>>> + if (rsc_capable) {
> >>>> + rfctl = IXGBE_READ_REG(hw, IXGBE_RFCTL);
> >>>> + if (rx_conf->enable_lro) {
> >>>> + rfctl &= ~(IXGBE_RFCTL_RSC_DIS |
> >>>> IXGBE_RFCTL_NFSW_DIS |
> >>>> + IXGBE_RFCTL_NFSR_DIS);
> >>>> + } else {
> >>>> + rfctl |= IXGBE_RFCTL_RSC_DIS;
> >>>> + }
> >>>> +
> >>>> + IXGBE_WRITE_REG(hw, IXGBE_RFCTL, rfctl);
> >>>> + }
> >>>> +
> >>>> +
> >>>> + /*
> >>>> * Configure CRC stripping, if any.
> >>>> */
> >>>> hlreg0 = IXGBE_READ_REG(hw, IXGBE_HLREG0);
> >>>> if (rx_conf->hw_strip_crc)
> >>>> hlreg0 |= IXGBE_HLREG0_RXCRCSTRP;
> >>>> - else
> >>>> + else {
> >>>> hlreg0 &= ~IXGBE_HLREG0_RXCRCSTRP;
> >>>> + if (rx_conf->enable_lro) {
> >>>> + /*
> >>>> + * According to chapter of 4.6.7.2.1 of the
> >>>> Spec Rev.
> >>>> + * 3.0 RSC configuration requires HW CRC
> >>>> stripping being
> >>>> + * enabled. If user requested both HW CRC
> >>>> stripping off
> >>>> + * and RSC on - return an error.
> >>>> + */
> >>>> + PMD_INIT_LOG(CRIT, "LRO can't be enabled when
> >>>> HW CRC "
> >>>> + "is disabled");
> >>>> + return -EINVAL;
> >>>> + }
> >>>> + }
> >>>>
> >>>> /*
> >>>> * Configure jumbo frame support, if any.
> >>>> @@ -3664,9 +4128,18 @@ ixgbe_dev_rx_init(struct rte_eth_dev *dev)
> >>>> * Configure Header Split
> >>>> */
> >>>> if (rx_conf->header_split) {
> >>>> + /*
> >>>> + * Print a warning if split_hdr_size is less
> >>>> + * than 128 bytes when RSC is requested.
> >>>> + */
> >>>> + if (rx_conf->enable_lro &&
> >>>> + rx_conf->split_hdr_size < 128)
> >>>> + PMD_INIT_LOG(INFO, "split_hdr_size less
> >>>> than "
> >>>> + "128 bytes (%d)!",
> >>>> + rx_conf->split_hdr_size);
> >>>> +
> >>>> if (hw->mac.type == ixgbe_mac_82599EB) {
> >>>> /* Must setup the PSRTYPE register */
> >>>> - uint32_t psrtype;
> >>>> psrtype = IXGBE_PSRTYPE_TCPHDR |
> >>>> IXGBE_PSRTYPE_UDPHDR |
> >>>> IXGBE_PSRTYPE_IPV4HDR |
> >>>> @@ -3679,7 +4152,20 @@ ixgbe_dev_rx_init(struct rte_eth_dev *dev)
> >>>> srrctl |=
> >>>> IXGBE_SRRCTL_DESCTYPE_HDR_SPLIT_ALWAYS;
> >>>> } else
> >>>> #endif
> >>>> + {
> >>>> srrctl = IXGBE_SRRCTL_DESCTYPE_ADV_ONEBUF;
> >>>> + /*
> >>>> + * Following the 4.6.7.2.1 chapter of the
> >>>> 82599/x540
> >>>> + * Spec if RSC is enabled the
> >>>> SRRCTL[n].BSIZEHEADER
> >>>> + * should be configured even if header split is
> >>>> not
> >>>> + * enabled. In the later case we will configure
> >>>> it 128
> >>>> + * bytes following the recommendation in the
> >>>> spec.
> >>>> + */
> >>>> + if (rx_conf->enable_lro)
> >>>> + srrctl |=
> >>>> + ((128 <<
> >>>> IXGBE_SRRCTL_BSIZEHDRSIZE_SHIFT) &
> >>>> +
> >>>> IXGBE_SRRCTL_BSIZEHDR_MASK);
> >>>> + }
> >>>>
> >>>> /* Set if packets are dropped when no descriptors
> >>>> available */
> >>>> if (rxq->drop_en)
> >>>> @@ -3696,6 +4182,13 @@ ixgbe_dev_rx_init(struct rte_eth_dev *dev)
> >>>> RTE_PKTMBUF_HEADROOM);
> >>>> srrctl |= ((buf_size >> IXGBE_SRRCTL_BSIZEPKT_SHIFT) &
> >>>> IXGBE_SRRCTL_BSIZEPKT_MASK);
> >>>> +
> >>>> + /*
> >>>> + * TODO: Consider setting the Receive Descriptor Minimum
> >>>> + * Threshold Size for and RSC case. This is not an
> >>>> obviously
> >>>> + * beneficiary option but the one worth considering...
> >>>> + */
> >>>> +
> >>>> IXGBE_WRITE_REG(hw, IXGBE_SRRCTL(rxq->reg_idx), srrctl);
> >>>>
> >>>> buf_size = (uint16_t) ((srrctl &
> >>>> IXGBE_SRRCTL_BSIZEPKT_MASK) <<
> >>>> @@ -3705,11 +4198,57 @@ ixgbe_dev_rx_init(struct rte_eth_dev *dev)
> >>>> if (dev->data->dev_conf.rxmode.max_rx_pkt_len +
> >>>> 2 * IXGBE_VLAN_TAG_SIZE >
> >>>> buf_size)
> >>>> dev->data->scattered_rx = 1;
> >>>> +
> >>>> + /* RSC per-queue configuration */
> >>>> + if (rx_conf->enable_lro) {
> >>>> + uint32_t eitr;
> >>>> +
> >>>> + rscctl =
> >>>> + IXGBE_READ_REG(hw,
> >>>> IXGBE_RSCCTL(rxq->reg_idx));
> >>>> + psrtype =
> >>>> + IXGBE_READ_REG(hw,
> >>>> IXGBE_PSRTYPE(rxq->reg_idx));
> >>>> + eitr = IXGBE_READ_REG(hw,
> >>>> IXGBE_EITR(rxq->reg_idx));
> >>>> +
> >>>> + rscctl |= IXGBE_RSCCTL_RSCEN;
> >>>> + rscctl |= get_rscctl_maxdesc(rxq->mb_pool);
> >>>> + psrtype |= IXGBE_PSRTYPE_TCPHDR;
> >>>> +
> >>>> + /*
> >>>> + * RSC: Set ITR interval corresponding to 2K
> >>>> ints/s.
> >>>> + *
> >>>> + * Full-sized RSC aggregations for a 10Gb/s
> >>>> link will
> >>>> + * arrive at about 20K aggregation/s rate.
> >>>> + *
> >>>> + * 2K inst/s rate will make only 10% of the
> >>>> + * aggregations to be closed due to the
> >>>> interrupt timer
> >>>> + * expiration for a streaming at wire-speed
> >>>> case.
> >>>> + *
> >>>> + * For a sparse streaming case this setting
> >>>> will yield
> >>>> + * at most 500us latency for a single RSC
> >>>> aggregation.
> >>>> + */
> >>>> + eitr |= (2000 | IXGBE_EITR_CNT_WDIS);
> >>> Again probably create some macro for ITR Interval default value here.
> >> Well, again - it's the only place where it's used and I've extensively
> >> explained it in the comments in the code. Therefore I think it's the
> >> most readable way to write this.
> >> If it would be used in at least two places - then I would have put it in
> >> a macro...
> > I think it is a good practise to use macros instead of raw numbers in such
> > places.
> > You probably can make these macros self-explanatory:
> > /* EITR Inteval in 2us uinits for 1G and 10G. */
> > #define IXGBE_EITR_INTERVAL_US 2
> >
> > #define IXGBE_EITR_INTERVAL_SHIFT 3
> >
> > #define IXGBE_EITR_INTERVAL(us) ((us) / IXGBE_EITR_INTERVAL_US <<
> > IXGBE_EITR_INTERVAL_SHIFT)
> >
> > /* at most 500us latency for a single RSC aggregation */
> > #define IXGHE_EITR_INTERVAL_DEFAULT IXGBE_EITR_INTERVAL(500)
>
> If this value would have a potential be changed one day or if it would
> going to be used somewhere else in the code I would immediately agree
> but here u've added 9 long lines of something that nobody would ever
> care about. The only thing that everybody would care what are the actual
> implication of this value on the RSC functionality. To understand that
> having macros like u propose instead of a proper comment like I propose
> doesn't help much. This is because the thing is not just about the EITR
> interval and the maximum latency. But if we keep my comment then we
> don't need any additional self-explanatory macros because everything has
> been explained in the comment already.
>
> If one day this parameter is going to be configured from the outside -
> then I agree that there would be a place for macros like above. For the
> current API state I think it would just pump up the code with useless
> code lines.
It is a good approach to do things in a proper way from the start.
Here you define macro and use them inside your code.
Then, when someone else will need to manipulate EITR interval - he can use the
macros
you defined and he wouldn't need to touch your code.
Same applies to the MAXDESC calculation above.
BTW:
eitr = IXGBE_READ_REG(hw, IXGBE_EITR(rxq->reg_idx));
...
eitr |= (2000 | IXGBE_EITR_CNT_WDIS);
Could EITR already contain some previous interval value?
If yes, then we probably either need to clear previous interval value first,
or just write new value of EITR without reading.
>
> >
> >>>> +
> >>>> + IXGBE_WRITE_REG(hw, IXGBE_RSCCTL(rxq->reg_idx),
> >>>> rscctl);
> >>>> + IXGBE_WRITE_REG(hw, IXGBE_PSRTYPE(rxq->reg_idx),
> >>>> +
> >>>> psrtype);
> >>>> + IXGBE_WRITE_REG(hw, IXGBE_EITR(rxq->reg_idx),
> >>>> eitr);
> >>>> +
> >>>> + /*
> >>>> + * RSC requires the mapping of the queue to the
> >>>> + * interrupt vector.
> >>>> + */
> >>>> + ixgbe_set_ivar(dev, rxq->reg_idx, i, 0);
> >>> Hm, wonder why do we need to setup IVAR for RSC?
> >>> Wouldn't just setting EITR be enough?
> >> Nope. See 82599 spec chapter 4.6.7.2.2.
> > I read it, though it doesn't say 'IVAR must be setup' like it does for
> > EITR.Inerval.
>
> 82599 Spec, Chapter 4.6.7.2.2 ("RSC Enablement" -> "Per Queue Setting"),
> the last bullet:
>
> "- Map the relevant Rx queues to an interrupt by setting the relevant IVAR
> registers."
>
> > That made me thought that it might be optional.
> >
> >> I think I even tried not to map
> >> the queues to IVAR and it didn't work... ;)
> > Pity, but not much we can in that case, I suppose.
> >
> >>>> +
> >>>> + rxq->rsc_en = 1;
> >>>> + }
> >>>> }
> >>>>
> >>>> if (rx_conf->enable_scatter)
> >>>> dev->data->scattered_rx = 1;
> >>>>
> >>>> + if (rx_conf->enable_lro)
> >>>> + dev->data->lro = 1;
> >>>> +
> >>>> set_rx_function(dev);
> >>>>
> >>>> /*
> >>>> @@ -3742,6 +4281,19 @@ ixgbe_dev_rx_init(struct rte_eth_dev *dev)
> >>>> IXGBE_WRITE_REG(hw, IXGBE_RDRXCTL, rdrxctl);
> >>>> }
> >>>>
> >>>> + /* Finalize RSC configuration */
> >>>> + if (rx_conf->enable_lro) {
> >>>> + /*
> >>>> + * Follow the instructions in the 4.6.7.2.1 of the Spec
> >>>> Rev. 3.0
> >>>> + */
> >>>> + rdrxctl = IXGBE_READ_REG(hw, IXGBE_RDRXCTL);
> >>>> + rdrxctl |= IXGBE_RDRXCTL_RSCACKC;
> >>>> + IXGBE_WRITE_REG(hw, IXGBE_RDRXCTL, rdrxctl);
> >>>> +
> >>>> + PMD_INIT_LOG(INFO, "enabling LRO mode");
> >>>> + }
> >>>> +
> >>>> +
> >>>> return 0;
> >>>> }
> >>>>
> >>>> diff --git a/lib/librte_pmd_ixgbe/ixgbe_rxtx.h
> >>>> b/lib/librte_pmd_ixgbe/ixgbe_rxtx.h
> >>>> index bbe5ff3..389173f 100644
> >>>> --- a/lib/librte_pmd_ixgbe/ixgbe_rxtx.h
> >>>> +++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx.h
> >>>> @@ -79,6 +79,10 @@ struct igb_rx_entry {
> >>>> struct rte_mbuf *mbuf; /**< mbuf associated with RX descriptor.
> >>>> */
> >>>> };
> >>>>
> >>>> +struct igb_rsc_entry {
> >>>> + struct rte_mbuf *fbuf; /**< First segment of the fragmented
> >>>> packet. */
> >>>> +};
> >>>> +
> >>>> /**
> >>>> * Structure associated with each descriptor of the TX ring of a TX
> >>>> queue.
> >>>> */
> >>>> @@ -105,6 +109,7 @@ struct igb_rx_queue {
> >>>> volatile uint32_t *rdt_reg_addr; /**< RDT register address. */
> >>>> volatile uint32_t *rdh_reg_addr; /**< RDH register address. */
> >>>> struct igb_rx_entry *sw_ring; /**< address of RX software ring.
> >>>> */
> >>>> + struct igb_rsc_entry *sw_rsc_ring; /**< address of RSC software
> >>>> ring. */
> >>>> struct rte_mbuf *pkt_first_seg; /**< First segment of current
> >>>> packet. */
> >>>> struct rte_mbuf *pkt_last_seg; /**< Last segment of current
> >>>> packet. */
> >>>> uint64_t mbuf_initializer; /**< value to init mbufs
> >>>> */
> >>>> @@ -126,6 +131,7 @@ struct igb_rx_queue {
> >>>> uint8_t port_id; /**< Device port identifier. */
> >>>> uint8_t crc_len; /**< 0 if CRC stripped, 4
> >>>> otherwise. */
> >>>> uint8_t drop_en; /**< If not 0, set
> >>>> SRRCTL.Drop_En. */
> >>>> + uint8_t rsc_en; /**< If not 0, RSC is enabled. */
> >>>> uint8_t rx_deferred_start; /**< not in global dev
> >>>> start. */
> >>>> #ifdef RTE_LIBRTE_IXGBE_RX_ALLOW_BULK_ALLOC
> >>>> /** need to alloc dummy mbuf, for wraparound when scanning hw
> >>>> ring */
> >>>> --
> >>>> 2.1.0
