| Message ID | 20210224111852.11947-4-ciara.loftus@intel.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Ferruh Yigit |
| Headers | show |
| Series | AF_XDP Preferred Busy Polling | expand |
| Context | Check | Description |
|---|---|---|
| ci/iol-mellanox-Functional | success | Functional Testing PASS |
| ci/iol-mellanox-Performance | success | Performance Testing PASS |
| ci/iol-testing | success | Testing PASS |
| ci/iol-abi-testing | success | Testing PASS |
| ci/iol-intel-Performance | success | Performance Testing PASS |
| ci/iol-intel-Functional | success | Functional Testing PASS |
| ci/intel-Testing | success | Testing PASS |
| ci/Intel-compilation | success | Compilation OK |
| ci/checkpatch | success | coding style OK |
On 2/24/2021 11:18 AM, Ciara Loftus wrote: > This commit introduces support for preferred busy polling > to the AF_XDP PMD. This feature aims to improve single-core > performance for AF_XDP sockets under heavy load. > > A new vdev arg is introduced called 'busy_budget' whose default > value is 64. busy_budget is the value supplied to the kernel > with the SO_BUSY_POLL_BUDGET socket option and represents the > busy-polling NAPI budget. To set the budget to a different value > eg. 256: > > --vdev=net_af_xdp0,iface=eth0,busy_budget=256 > > Preferred busy polling is enabled by default provided a kernel with > version >= v5.11 is in use. To disable it, set the budget to zero. > > The following settings are also strongly recommended to be used in > conjunction with this feature: > > echo 2 | sudo tee /sys/class/net/eth0/napi_defer_hard_irqs > echo 200000 | sudo tee /sys/class/net/eth0/gro_flush_timeout > > .. where eth0 is the interface being used by the PMD. > > Signed-off-by: Ciara Loftus <ciara.loftus@intel.com> > --- > doc/guides/nics/af_xdp.rst | 38 ++++++++++++- > drivers/net/af_xdp/compat.h | 13 +++++ > drivers/net/af_xdp/rte_eth_af_xdp.c | 85 ++++++++++++++++++++++++----- > 3 files changed, 121 insertions(+), 15 deletions(-) Can you please update the release notes too to announce the feature? <...> > @@ -39,3 +39,16 @@ create_shared_socket(struct xsk_socket **xsk_ptr __rte_unused, > return -1; > } > #endif > + > +#ifdef XDP_USE_NEED_WAKEUP > +static int > +syscall_needed(struct xsk_ring_prod *q, uint32_t busy_budget) > +{ > + return xsk_ring_prod__needs_wakeup(q) | busy_budget; > +} > +#else > +syscall_needed(struct xsk_ring_prod *q __rte_unused, uint32_t busy_budget) > +{ > + return busy_budget; > +} Is the return type missing in the definition? Also for the case when both 'XDP_USE_NEED_WAKEUP' & 'SO_PREFER_BUSY_POLL' this function will always return '0', but current implementation doesn't know this in the compile time and compiler can't optimize for it, do you think does it make sense to do this optimization? <...> > @@ -1628,8 +1670,22 @@ rte_pmd_af_xdp_probe(struct rte_vdev_device *dev) > return -EINVAL; > } > > +#ifdef SO_PREFER_BUSY_POLL > + busy_budget = busy_budget == -1 ? ETH_AF_XDP_DFLT_BUSY_BUDGET : > + busy_budget; > + if (!busy_budget) > + AF_XDP_LOG(ERR, "Preferred busy polling disabled\n"); Is this an error case? What do you think changing the log level to DEBUG or INFO? Also how these compile time flags will work if the compiled environment and run environment kernel version are different and incompatible? Overall can it be possible to detect the support on runtime via 'setsockopt()' without compile time macros and eliminate the compile time flags? Does it make sense?
> > On 2/24/2021 11:18 AM, Ciara Loftus wrote: > > This commit introduces support for preferred busy polling > > to the AF_XDP PMD. This feature aims to improve single-core > > performance for AF_XDP sockets under heavy load. > > > > A new vdev arg is introduced called 'busy_budget' whose default > > value is 64. busy_budget is the value supplied to the kernel > > with the SO_BUSY_POLL_BUDGET socket option and represents the > > busy-polling NAPI budget. To set the budget to a different value > > eg. 256: > > > > --vdev=net_af_xdp0,iface=eth0,busy_budget=256 > > > > Preferred busy polling is enabled by default provided a kernel with > > version >= v5.11 is in use. To disable it, set the budget to zero. > > > > The following settings are also strongly recommended to be used in > > conjunction with this feature: > > > > echo 2 | sudo tee /sys/class/net/eth0/napi_defer_hard_irqs > > echo 200000 | sudo tee /sys/class/net/eth0/gro_flush_timeout > > > > .. where eth0 is the interface being used by the PMD. > > > > Signed-off-by: Ciara Loftus <ciara.loftus@intel.com> > > --- > > doc/guides/nics/af_xdp.rst | 38 ++++++++++++- > > drivers/net/af_xdp/compat.h | 13 +++++ > > drivers/net/af_xdp/rte_eth_af_xdp.c | 85 > ++++++++++++++++++++++++----- > > 3 files changed, 121 insertions(+), 15 deletions(-) > > Can you please update the release notes too to announce the feature? Will do. > > <...> > > > > @@ -39,3 +39,16 @@ create_shared_socket(struct xsk_socket **xsk_ptr > __rte_unused, > > return -1; > > } > > #endif > > + > > +#ifdef XDP_USE_NEED_WAKEUP > > +static int > > +syscall_needed(struct xsk_ring_prod *q, uint32_t busy_budget) > > +{ > > + return xsk_ring_prod__needs_wakeup(q) | busy_budget; > > +} > > +#else > > +syscall_needed(struct xsk_ring_prod *q __rte_unused, uint32_t > busy_budget) > > +{ > > + return busy_budget; > > +} > > Is the return type missing in the definition? Yes. Thanks for spotting this. > > Also for the case when both 'XDP_USE_NEED_WAKEUP' & > 'SO_PREFER_BUSY_POLL' this > function will always return '0', but current implementation doesn't know this > in > the compile time and compiler can't optimize for it, do you think does it make > sense to do this optimization? It makes sense assuming the compile environment and run environment are the same. However you make a valid point below. If the environments are different, we can't make this optimization because we can’t rely on the presence of the flags alone to tell us if these features are supported. More below. > > <...> > > > @@ -1628,8 +1670,22 @@ rte_pmd_af_xdp_probe(struct rte_vdev_device > *dev) > > return -EINVAL; > > } > > > > +#ifdef SO_PREFER_BUSY_POLL > > + busy_budget = busy_budget == -1 ? > ETH_AF_XDP_DFLT_BUSY_BUDGET : > > + busy_budget; > > + if (!busy_budget) > > + AF_XDP_LOG(ERR, "Preferred busy polling disabled\n"); > > Is this an error case? What do you think changing the log level to DEBUG or > INFO? +1 for INFO > > Also how these compile time flags will work if the compiled environment and > run > environment kernel version are different and incompatible? This is a valid point. Right now if XDP_USE_NEED_WAKEUP is defined we assume the functionality is available in the kernel. If it's not, socket creation will fail and we abort. Perhaps we should retry socket creation without the flag if we get this failure. And record if support is available in a runtime variable. I'll look at adding this as another patch to the v2 series. > > Overall can it be possible to detect the support on runtime via 'setsockopt()' > without compile time macros and eliminate the compile time flags? Does it > make > sense? I think this can be done. It should allow applications compiled on older kernels without SO_PREFER_BUSY_POLL run on newer kernels with the feature. I will tackle this in the v2. Thanks for your feedback! Ciara
> > > > On 2/24/2021 11:18 AM, Ciara Loftus wrote: > > > This commit introduces support for preferred busy polling > > > to the AF_XDP PMD. This feature aims to improve single-core > > > performance for AF_XDP sockets under heavy load. > > > > > > A new vdev arg is introduced called 'busy_budget' whose default > > > value is 64. busy_budget is the value supplied to the kernel > > > with the SO_BUSY_POLL_BUDGET socket option and represents the > > > busy-polling NAPI budget. To set the budget to a different value > > > eg. 256: > > > > > > --vdev=net_af_xdp0,iface=eth0,busy_budget=256 > > > > > > Preferred busy polling is enabled by default provided a kernel with > > > version >= v5.11 is in use. To disable it, set the budget to zero. > > > > > > The following settings are also strongly recommended to be used in > > > conjunction with this feature: > > > > > > echo 2 | sudo tee /sys/class/net/eth0/napi_defer_hard_irqs > > > echo 200000 | sudo tee /sys/class/net/eth0/gro_flush_timeout > > > > > > .. where eth0 is the interface being used by the PMD. > > > > > > Signed-off-by: Ciara Loftus <ciara.loftus@intel.com> > > > --- > > > doc/guides/nics/af_xdp.rst | 38 ++++++++++++- > > > drivers/net/af_xdp/compat.h | 13 +++++ > > > drivers/net/af_xdp/rte_eth_af_xdp.c | 85 > > ++++++++++++++++++++++++----- > > > 3 files changed, 121 insertions(+), 15 deletions(-) > > > > Can you please update the release notes too to announce the feature? > > Will do. > > > > > <...> > > > > > > > @@ -39,3 +39,16 @@ create_shared_socket(struct xsk_socket **xsk_ptr > > __rte_unused, > > > return -1; > > > } > > > #endif > > > + > > > +#ifdef XDP_USE_NEED_WAKEUP > > > +static int > > > +syscall_needed(struct xsk_ring_prod *q, uint32_t busy_budget) > > > +{ > > > + return xsk_ring_prod__needs_wakeup(q) | busy_budget; > > > +} > > > +#else > > > +syscall_needed(struct xsk_ring_prod *q __rte_unused, uint32_t > > busy_budget) > > > +{ > > > + return busy_budget; > > > +} > > > > Is the return type missing in the definition? > > Yes. Thanks for spotting this. > > > > > Also for the case when both 'XDP_USE_NEED_WAKEUP' & > > 'SO_PREFER_BUSY_POLL' this > > function will always return '0', but current implementation doesn't know > this > > in > > the compile time and compiler can't optimize for it, do you think does it > make > > sense to do this optimization? > > It makes sense assuming the compile environment and run environment are > the same. > However you make a valid point below. If the environments are different, > we can't make this optimization because we can’t rely on the presence of the > flags alone to tell us if these features are supported. More below. > > > > > <...> > > > > > @@ -1628,8 +1670,22 @@ rte_pmd_af_xdp_probe(struct > rte_vdev_device > > *dev) > > > return -EINVAL; > > > } > > > > > > +#ifdef SO_PREFER_BUSY_POLL > > > + busy_budget = busy_budget == -1 ? > > ETH_AF_XDP_DFLT_BUSY_BUDGET : > > > + busy_budget; > > > + if (!busy_budget) > > > + AF_XDP_LOG(ERR, "Preferred busy polling disabled\n"); > > > > Is this an error case? What do you think changing the log level to DEBUG or > > INFO? > > +1 for INFO > > > > > Also how these compile time flags will work if the compiled environment > and > > run > > environment kernel version are different and incompatible? > > This is a valid point. Right now if XDP_USE_NEED_WAKEUP is defined we > assume the functionality is available in the kernel. If it's not, socket creation > will fail and we abort. Perhaps we should retry socket creation without the > flag if we get this failure. And record if support is available in a runtime > variable. I'll look at adding this as another patch to the v2 series. Hi Ferruh, I looked at this a little more. For the v2 I'll make sure busy poll can work in these environments with different compile-time and run-time kernels and use setsockopt() to detect support in the kernel. Since it will require significant changes and validation I'll submit a separate series ensuring the same for the other existing flags (XDP_USE_NEED_WAKEUP / XDP_UMEM_UNALIGNED_CHUNK_FLAG / shared umem). Thanks, Ciara > > > > > Overall can it be possible to detect the support on runtime via > 'setsockopt()' > > without compile time macros and eliminate the compile time flags? Does it > > make > > sense? > > I think this can be done. It should allow applications compiled on older > kernels without SO_PREFER_BUSY_POLL run on newer kernels with the > feature. > I will tackle this in the v2. > > Thanks for your feedback! > > Ciara
diff --git a/doc/guides/nics/af_xdp.rst b/doc/guides/nics/af_xdp.rst index 5ed24374f8..8bf40b5f0f 100644 --- a/doc/guides/nics/af_xdp.rst +++ b/doc/guides/nics/af_xdp.rst @@ -35,6 +35,7 @@ The following options can be provided to set up an af_xdp port in DPDK. * ``shared_umem`` - PMD will attempt to share UMEM with others (optional, default 0); * ``xdp_prog`` - path to custom xdp program (optional, default none); +* ``busy_budget`` - busy polling budget (optional, default 64); Prerequisites ------------- @@ -51,6 +52,7 @@ This is a Linux-specific PMD, thus the following prerequisites apply: * For shared_umem, it requires kernel version v5.10 or later and libbpf version v0.2.0 or later. * For 32-bit OS, a kernel with version 5.4 or later is required. +* For busy polling, kernel version v5.11 or later is required. Set up an af_xdp interface ----------------------------- @@ -107,4 +109,38 @@ Limitations .. code-block:: console --vdev net_af_xdp0,iface=ens786f1,shared_umem=1 \ - --vdev net_af_xdp1,iface=ens786f2,shared_umem=1 \ \ No newline at end of file + --vdev net_af_xdp1,iface=ens786f2,shared_umem=1 \ + +- **Preferred Busy Polling** + + The SO_PREFER_BUSY_POLL socket option was introduced in kernel v5.11. It can + deliver a performance improvement for sockets with heavy traffic loads and + can significantly improve single-core performance in this context. + + The feature is enabled by default in the AF_XDP PMD. To disable it, set the + 'busy_budget' vdevarg to zero: + + .. code-block:: console + + --vdev net_af_xdp0,iface=ens786f1,busy_budget=0 + + The default 'busy_budget' is 64 and it represents the number of packets the + kernel will attempt to process in the netdev's NAPI context. You can change + the value for example to 256 like so: + + .. code-block:: console + + --vdev net_af_xdp0,iface=ens786f1,busy_budget=256 + + It is also strongly recommended to set the following for optimal performance: + + .. code-block:: console + + echo 2 | sudo tee /sys/class/net/ens786f1/napi_defer_hard_irqs + echo 200000 | sudo tee /sys/class/net/ens786f1/gro_flush_timeout + + The above defers interrupts for interface ens786f1 and instead schedules its + NAPI context from a watchdog timer instead of from softirqs. More information + on this feature can be found at [1]. + + [1] https://lwn.net/Articles/837010/ \ No newline at end of file diff --git a/drivers/net/af_xdp/compat.h b/drivers/net/af_xdp/compat.h index 7aa40d522e..1d247a50b2 100644 --- a/drivers/net/af_xdp/compat.h +++ b/drivers/net/af_xdp/compat.h @@ -39,3 +39,16 @@ create_shared_socket(struct xsk_socket **xsk_ptr __rte_unused, return -1; } #endif + +#ifdef XDP_USE_NEED_WAKEUP +static int +syscall_needed(struct xsk_ring_prod *q, uint32_t busy_budget) +{ + return xsk_ring_prod__needs_wakeup(q) | busy_budget; +} +#else +syscall_needed(struct xsk_ring_prod *q __rte_unused, uint32_t busy_budget) +{ + return busy_budget; +} +#endif diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c b/drivers/net/af_xdp/rte_eth_af_xdp.c index 34b15aa3d0..5091239b38 100644 --- a/drivers/net/af_xdp/rte_eth_af_xdp.c +++ b/drivers/net/af_xdp/rte_eth_af_xdp.c @@ -65,6 +65,8 @@ RTE_LOG_REGISTER(af_xdp_logtype, pmd.net.af_xdp, NOTICE); #define ETH_AF_XDP_DFLT_NUM_DESCS XSK_RING_CONS__DEFAULT_NUM_DESCS #define ETH_AF_XDP_DFLT_START_QUEUE_IDX 0 #define ETH_AF_XDP_DFLT_QUEUE_COUNT 1 +#define ETH_AF_XDP_DFLT_BUSY_BUDGET 64 +#define ETH_AF_XDP_DFLT_BUSY_TIMEOUT 20 #define ETH_AF_XDP_RX_BATCH_SIZE 512 #define ETH_AF_XDP_TX_BATCH_SIZE 512 @@ -100,6 +102,7 @@ struct pkt_rx_queue { struct pkt_tx_queue *pair; struct pollfd fds[1]; int xsk_queue_idx; + uint32_t busy_budget; }; struct tx_stats { @@ -140,6 +143,7 @@ struct pmd_internals { #define ETH_AF_XDP_QUEUE_COUNT_ARG "queue_count" #define ETH_AF_XDP_SHARED_UMEM_ARG "shared_umem" #define ETH_AF_XDP_PROG_ARG "xdp_prog" +#define ETH_AF_XDP_BUDGET_ARG "busy_budget" static const char * const valid_arguments[] = { ETH_AF_XDP_IFACE_ARG, @@ -147,6 +151,7 @@ static const char * const valid_arguments[] = { ETH_AF_XDP_QUEUE_COUNT_ARG, ETH_AF_XDP_SHARED_UMEM_ARG, ETH_AF_XDP_PROG_ARG, + ETH_AF_XDP_BUDGET_ARG, NULL }; @@ -261,11 +266,9 @@ af_xdp_rx_zc(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts) nb_pkts = xsk_ring_cons__peek(rx, nb_pkts, &idx_rx); if (nb_pkts == 0) { -#if defined(XDP_USE_NEED_WAKEUP) - if (xsk_ring_prod__needs_wakeup(fq)) + if (syscall_needed(&rxq->fq, rxq->busy_budget)) recvfrom(xsk_socket__fd(rxq->xsk), NULL, 0, MSG_DONTWAIT, NULL, NULL); -#endif return 0; } @@ -334,11 +337,9 @@ af_xdp_rx_cp(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts) nb_pkts = xsk_ring_cons__peek(rx, nb_pkts, &idx_rx); if (nb_pkts == 0) { -#if defined(XDP_USE_NEED_WAKEUP) - if (xsk_ring_prod__needs_wakeup(fq)) + if (syscall_needed(&rxq->fq, rxq->busy_budget)) recvfrom(xsk_socket__fd(rxq->xsk), NULL, 0, MSG_DONTWAIT, NULL, NULL); -#endif return 0; } @@ -422,9 +423,7 @@ kick_tx(struct pkt_tx_queue *txq, struct xsk_ring_cons *cq) pull_umem_cq(umem, XSK_RING_CONS__DEFAULT_NUM_DESCS, cq); -#if defined(XDP_USE_NEED_WAKEUP) - if (xsk_ring_prod__needs_wakeup(&txq->tx)) -#endif + if (syscall_needed(&txq->tx, txq->pair->busy_budget)) { while (send(xsk_socket__fd(txq->pair->xsk), NULL, 0, MSG_DONTWAIT) < 0) { /* some thing unexpected */ @@ -437,6 +436,7 @@ kick_tx(struct pkt_tx_queue *txq, struct xsk_ring_cons *cq) XSK_RING_CONS__DEFAULT_NUM_DESCS, cq); } + } } #if defined(XDP_UMEM_UNALIGNED_CHUNK_FLAG) @@ -1145,6 +1145,39 @@ xsk_configure(struct pmd_internals *internals, struct pkt_rx_queue *rxq, goto err; } +#ifdef SO_PREFER_BUSY_POLL + if (rxq->busy_budget) { + int sock_opt = 1; + int fd = xsk_socket__fd(rxq->xsk); + + ret = setsockopt(fd, SOL_SOCKET, SO_PREFER_BUSY_POLL, + (void *)&sock_opt, sizeof(sock_opt)); + if (ret < 0) { + AF_XDP_LOG(ERR, "Failed to set SO_PREFER_BUSY_POLL\n"); + goto err; + } + + sock_opt = ETH_AF_XDP_DFLT_BUSY_TIMEOUT; + ret = setsockopt(fd, SOL_SOCKET, SO_BUSY_POLL, (void *)&sock_opt, + sizeof(sock_opt)); + if (ret < 0) { + AF_XDP_LOG(ERR, "Failed to set SO_BUSY_POLL\n"); + goto err; + } + + sock_opt = rxq->busy_budget; + ret = setsockopt(fd, SOL_SOCKET, SO_BUSY_POLL_BUDGET, + (void *)&sock_opt, sizeof(sock_opt)); + if (ret < 0) { + AF_XDP_LOG(ERR, "Failed to set SO_BUSY_POLL_BUDGET\n"); + goto err; + } else { + AF_XDP_LOG(INFO, "Busy polling budget set to: %u\n", + rxq->busy_budget); + } + } +#endif + #if defined(XDP_UMEM_UNALIGNED_CHUNK_FLAG) if (rte_pktmbuf_alloc_bulk(rxq->umem->mb_pool, fq_bufs, reserve_size)) { AF_XDP_LOG(DEBUG, "Failed to get enough buffers for fq.\n"); @@ -1416,7 +1449,8 @@ xdp_get_channels_info(const char *if_name, int *max_queues, static int parse_parameters(struct rte_kvargs *kvlist, char *if_name, int *start_queue, - int *queue_cnt, int *shared_umem, char *prog_path) + int *queue_cnt, int *shared_umem, char *prog_path, + int *busy_budget) { int ret; @@ -1447,6 +1481,11 @@ parse_parameters(struct rte_kvargs *kvlist, char *if_name, int *start_queue, if (ret < 0) goto free_kvlist; + ret = rte_kvargs_process(kvlist, ETH_AF_XDP_BUDGET_ARG, + &parse_integer_arg, busy_budget); + if (ret < 0) + goto free_kvlist; + free_kvlist: rte_kvargs_free(kvlist); return ret; @@ -1485,7 +1524,7 @@ get_iface_info(const char *if_name, static struct rte_eth_dev * init_internals(struct rte_vdev_device *dev, const char *if_name, int start_queue_idx, int queue_cnt, int shared_umem, - const char *prog_path) + const char *prog_path, int busy_budget) { const char *name = rte_vdev_device_name(dev); const unsigned int numa_node = dev->device.numa_node; @@ -1546,6 +1585,7 @@ init_internals(struct rte_vdev_device *dev, const char *if_name, internals->rx_queues[i].pair = &internals->tx_queues[i]; internals->rx_queues[i].xsk_queue_idx = start_queue_idx + i; internals->tx_queues[i].xsk_queue_idx = start_queue_idx + i; + internals->rx_queues[i].busy_budget = busy_budget; } ret = get_iface_info(if_name, &internals->eth_addr, @@ -1589,6 +1629,7 @@ rte_pmd_af_xdp_probe(struct rte_vdev_device *dev) int xsk_queue_cnt = ETH_AF_XDP_DFLT_QUEUE_COUNT; int shared_umem = 0; char prog_path[PATH_MAX] = {'\0'}; + int busy_budget = -1; struct rte_eth_dev *eth_dev = NULL; const char *name; @@ -1618,7 +1659,8 @@ rte_pmd_af_xdp_probe(struct rte_vdev_device *dev) dev->device.numa_node = rte_socket_id(); if (parse_parameters(kvlist, if_name, &xsk_start_queue_idx, - &xsk_queue_cnt, &shared_umem, prog_path) < 0) { + &xsk_queue_cnt, &shared_umem, prog_path, + &busy_budget) < 0) { AF_XDP_LOG(ERR, "Invalid kvargs value\n"); return -EINVAL; } @@ -1628,8 +1670,22 @@ rte_pmd_af_xdp_probe(struct rte_vdev_device *dev) return -EINVAL; } +#ifdef SO_PREFER_BUSY_POLL + busy_budget = busy_budget == -1 ? ETH_AF_XDP_DFLT_BUSY_BUDGET : + busy_budget; + if (!busy_budget) + AF_XDP_LOG(ERR, "Preferred busy polling disabled\n"); +#else + if (busy_budget > 0) { + AF_XDP_LOG(ERR, "Kernel does not support SO_PREFER_BUSY_POLL\n"); + return -ENOTSUP; + } + busy_budget = 0; +#endif + eth_dev = init_internals(dev, if_name, xsk_start_queue_idx, - xsk_queue_cnt, shared_umem, prog_path); + xsk_queue_cnt, shared_umem, prog_path, + busy_budget); if (eth_dev == NULL) { AF_XDP_LOG(ERR, "Failed to init internals\n"); return -1; @@ -1674,4 +1730,5 @@ RTE_PMD_REGISTER_PARAM_STRING(net_af_xdp, "start_queue=<int> " "queue_count=<int> " "shared_umem=<int> " - "xdp_prog=<string> "); + "xdp_prog=<string> " + "busy_budget=<int>");
This commit introduces support for preferred busy polling to the AF_XDP PMD. This feature aims to improve single-core performance for AF_XDP sockets under heavy load. A new vdev arg is introduced called 'busy_budget' whose default value is 64. busy_budget is the value supplied to the kernel with the SO_BUSY_POLL_BUDGET socket option and represents the busy-polling NAPI budget. To set the budget to a different value eg. 256: --vdev=net_af_xdp0,iface=eth0,busy_budget=256 Preferred busy polling is enabled by default provided a kernel with version >= v5.11 is in use. To disable it, set the budget to zero. The following settings are also strongly recommended to be used in conjunction with this feature: echo 2 | sudo tee /sys/class/net/eth0/napi_defer_hard_irqs echo 200000 | sudo tee /sys/class/net/eth0/gro_flush_timeout .. where eth0 is the interface being used by the PMD. Signed-off-by: Ciara Loftus <ciara.loftus@intel.com> --- doc/guides/nics/af_xdp.rst | 38 ++++++++++++- drivers/net/af_xdp/compat.h | 13 +++++ drivers/net/af_xdp/rte_eth_af_xdp.c | 85 ++++++++++++++++++++++++----- 3 files changed, 121 insertions(+), 15 deletions(-)