On 06/11, Bobby Eshleman wrote: > From: Bobby Eshleman <[email protected]> > > Every devmem dmabuf binding today hands the page_pool PAGE_SIZE niovs. > This caps a single RX descriptor at PAGE_SIZE, burning CPU on buffer > churn for large flows. > > Add a bind-time netlink attribute, NETDEV_A_DMABUF_RX_BUF_SIZE, that > lets userspace request a larger niov size. The value must be a power of > two >= PAGE_SIZE. > > Measurements > ------------ > Setup: kperf in devmem RX/TX cuda mode, 4 flows, 64 MB messages, 60s, > dctcp, num-rx-queues=4, dmabuf-rx/tx-size-mb=2048, 10 runs per niov > size, mlx5. > > CPU Util: > > niov net sirq % net idle % app sys % app idle > % > ----- ---------------- ---------------- ---------------- > ---------------- > 4K 62.38 +/- 8.27 33.40 +/- 7.51 54.15 +/- 10.23 43.67 +/- > 10.53 > 16K 58.91 +/- 5.35 35.23 +/- 5.88 41.05 +/- 8.87 56.42 +/- > 9.24 > 32K 64.12 +/- 0.68 31.09 +/- 1.48 44.54 +/- 3.51 52.63 +/- > 3.65 > 64K 54.69 +/- 5.54 39.67 +/- 5.81 35.47 +/- 3.11 61.97 +/- > 3.27 > > RX app sys % drops ~19% from 4K to 64K. > > Throughput: > > niov RX dev Gbps RX flow avg Gbps > ----- ---------------- ----------------- > 4K 300.63 +/- 53.21 75.16 +/- 13.30 > 16K 321.35 +/- 28.20 80.34 +/- 7.05 > 32K 347.63 +/- 2.20 86.91 +/- 0.55 > 64K 332.11 +/- 14.26 83.03 +/- 3.56 > > Throughput seems to increase, but the stdev is pretty wide so could just > be noise. > > kperf support (not yet merged): > https://github.com/facebookexperimental/kperf/commit/8837577f920876bce6986ec18869ac04439ebcd2 > > Signed-off-by: Bobby Eshleman <[email protected]> > --- > Documentation/netlink/specs/netdev.yaml | 8 ++++++ > include/uapi/linux/netdev.h | 1 + > net/core/devmem.c | 51 > +++++++++++++++++++-------------- > net/core/devmem.h | 13 ++++++--- > net/core/netdev-genl-gen.c | 5 ++-- > net/core/netdev-genl.c | 19 ++++++++++-- > tools/include/uapi/linux/netdev.h | 1 + > 7 files changed, 69 insertions(+), 29 deletions(-) > > diff --git a/Documentation/netlink/specs/netdev.yaml > b/Documentation/netlink/specs/netdev.yaml > index 49862b666d7d..395eaa0f9580 100644 > --- a/Documentation/netlink/specs/netdev.yaml > +++ b/Documentation/netlink/specs/netdev.yaml > @@ -591,6 +591,13 @@ attribute-sets: > type: u32 > checks: > min: 1 > + - > + name: rx-buf-size > + doc: | > + Size in bytes of each RX buffer the NIC writes into from the bound > + dmabuf. Must be a power of two and >= PAGE_SIZE; defaults to > + PAGE_SIZE. > + type: u32 > > operations: > list: > @@ -805,6 +812,7 @@ operations: > - ifindex > - fd > - queues > + - rx-buf-size > reply: > attributes: > - id > diff --git a/include/uapi/linux/netdev.h b/include/uapi/linux/netdev.h > index 7df1056a35fd..180a4ffffd60 100644 > --- a/include/uapi/linux/netdev.h > +++ b/include/uapi/linux/netdev.h > @@ -217,6 +217,7 @@ enum { > NETDEV_A_DMABUF_QUEUES, > NETDEV_A_DMABUF_FD, > NETDEV_A_DMABUF_ID, > + NETDEV_A_DMABUF_RX_BUF_SIZE, > > __NETDEV_A_DMABUF_MAX, > NETDEV_A_DMABUF_MAX = (__NETDEV_A_DMABUF_MAX - 1) > diff --git a/net/core/devmem.c b/net/core/devmem.c > index 957d6b96216b..3ce3cc14bec0 100644 > --- a/net/core/devmem.c > +++ b/net/core/devmem.c > @@ -46,7 +46,7 @@ static dma_addr_t net_devmem_get_dma_addr(const struct > net_iov *niov) > > owner = net_devmem_iov_to_chunk_owner(niov); > return owner->base_dma_addr + > - ((dma_addr_t)net_iov_idx(niov) << PAGE_SHIFT); > + ((dma_addr_t)net_iov_idx(niov) << owner->binding->niov_shift); > } > > static void net_devmem_dmabuf_binding_release(struct percpu_ref *ref) > @@ -93,13 +93,14 @@ net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding > *binding) > ssize_t offset; > ssize_t index; > > - dma_addr = gen_pool_alloc_owner(binding->chunk_pool, PAGE_SIZE, > + dma_addr = gen_pool_alloc_owner(binding->chunk_pool, > + 1UL << binding->niov_shift, > (void **)&owner); > if (!dma_addr) > return NULL; > > offset = dma_addr - owner->base_dma_addr; > - index = offset / PAGE_SIZE; > + index = offset >> binding->niov_shift; > niov = &owner->area.niovs[index]; > > niov->desc.pp_magic = 0; > @@ -113,12 +114,13 @@ void net_devmem_free_dmabuf(struct net_iov *niov) > { > struct net_devmem_dmabuf_binding *binding = > net_devmem_iov_binding(niov); > unsigned long dma_addr = net_devmem_get_dma_addr(niov); > + size_t niov_size = 1UL << binding->niov_shift; > > if (WARN_ON(!gen_pool_has_addr(binding->chunk_pool, dma_addr, > - PAGE_SIZE))) > + niov_size))) > return; > > - gen_pool_free(binding->chunk_pool, dma_addr, PAGE_SIZE); > + gen_pool_free(binding->chunk_pool, dma_addr, niov_size); > } > > void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding) > @@ -163,6 +165,9 @@ int net_devmem_bind_dmabuf_to_queue(struct net_device > *dev, u32 rxq_idx, > u32 xa_idx; > int err; > > + if (binding->niov_shift != PAGE_SHIFT) > + mp_params.rx_page_size = 1U << binding->niov_shift; > + > err = netif_mp_open_rxq(dev, rxq_idx, &mp_params, extack); > if (err) > return err; > @@ -184,14 +189,16 @@ struct net_devmem_dmabuf_binding * > net_devmem_bind_dmabuf(struct net_device *dev, void *vdev, > struct device *dma_dev, > enum dma_data_direction direction, > - unsigned int dmabuf_fd, struct netdev_nl_sock *priv, > + unsigned int dmabuf_fd, unsigned int niov_shift, > + struct netdev_nl_sock *priv, > struct netlink_ext_ack *extack) > { > struct net_devmem_dmabuf_binding *binding; > + size_t niov_size = 1UL << niov_shift; > static u32 id_alloc_next; > + unsigned int sg_idx, i; > struct scatterlist *sg; > struct dma_buf *dmabuf; > - unsigned int sg_idx, i; > unsigned long virtual; > int err; > > @@ -213,6 +220,7 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev, > > binding->dev = dev; > binding->vdev = vdev; > + binding->niov_shift = niov_shift; > xa_init_flags(&binding->bound_rxqs, XA_FLAGS_ALLOC); > > err = percpu_ref_init(&binding->ref, > @@ -248,18 +256,14 @@ net_devmem_bind_dmabuf(struct net_device *dev, void > *vdev, > goto err_unmap; > } > binding->tx_vec = kvmalloc_objs(struct net_iov *, > - dmabuf->size / PAGE_SIZE); > + dmabuf->size >> niov_shift); > if (!binding->tx_vec) { > err = -ENOMEM; > goto err_unmap; > } > } > > - /* For simplicity we expect to make PAGE_SIZE allocations, but the > - * binding can be much more flexible than that. We may be able to > - * allocate MTU sized chunks here. Leave that for future work... > - */ > - binding->chunk_pool = gen_pool_create(PAGE_SHIFT, > + binding->chunk_pool = gen_pool_create(niov_shift, > dev_to_node(&dev->dev)); > if (!binding->chunk_pool) { > err = -ENOMEM; > @@ -273,9 +277,12 @@ net_devmem_bind_dmabuf(struct net_device *dev, void > *vdev, > size_t len = sg_dma_len(sg); > struct net_iov *niov; > > - if (!IS_ALIGNED(len, PAGE_SIZE)) { > + if (!IS_ALIGNED(dma_addr, niov_size) || > + !IS_ALIGNED(len, niov_size)) { > err = -EINVAL; > - NL_SET_ERR_MSG(extack, "dma-buf SG length must be > PAGE_SIZE aligned"); > + NL_SET_ERR_MSG_FMT(extack, > + "dmabuf sg entry (addr=%pad, > len=%zu) not aligned to niov size %zu", > + &dma_addr, len, niov_size); > goto err_free_chunks; > } > > @@ -288,7 +295,7 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev, > > owner->area.base_virtual = virtual; > owner->base_dma_addr = dma_addr; > - owner->area.num_niovs = len / PAGE_SIZE; > + owner->area.num_niovs = len >> niov_shift; > owner->binding = binding; > > err = gen_pool_add_owner(binding->chunk_pool, dma_addr, > @@ -313,7 +320,7 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev, > page_pool_set_dma_addr_netmem(net_iov_to_netmem(niov), > > net_devmem_get_dma_addr(niov)); > if (direction == DMA_TO_DEVICE) > - binding->tx_vec[owner->area.base_virtual / > PAGE_SIZE + i] = niov; > + binding->tx_vec[(owner->area.base_virtual >> > niov_shift) + i] = niov; > } > > virtual += len; > @@ -430,13 +437,15 @@ struct net_iov * > net_devmem_get_niov_at(struct net_devmem_dmabuf_binding *binding, > size_t virt_addr, size_t *off, size_t *size) > { > + size_t niov_size = 1UL << binding->niov_shift; > + > if (virt_addr >= binding->dmabuf->size) > return NULL; > > - *off = virt_addr % PAGE_SIZE; > - *size = PAGE_SIZE - *off; > + *off = virt_addr & (niov_size - 1); > + *size = niov_size - *off; > > - return binding->tx_vec[virt_addr / PAGE_SIZE]; > + return binding->tx_vec[virt_addr >> binding->niov_shift]; > } > > /*** "Dmabuf devmem memory provider" ***/ > @@ -454,7 +463,7 @@ int mp_dmabuf_devmem_init(struct page_pool *pool) > pool->dma_sync = false; > pool->dma_sync_for_cpu = false; > > - if (pool->p.order != 0) > + if (pool->p.order != binding->niov_shift - PAGE_SHIFT) > return -E2BIG; > > net_devmem_dmabuf_binding_get(binding); > diff --git a/net/core/devmem.h b/net/core/devmem.h > index 3852a56036cb..4a293a7d1149 100644 > --- a/net/core/devmem.h > +++ b/net/core/devmem.h > @@ -71,6 +71,8 @@ struct net_devmem_dmabuf_binding { > */ > struct net_iov **tx_vec; > > + unsigned int niov_shift; > + > struct work_struct unbind_w; > }; > > @@ -93,7 +95,8 @@ struct net_devmem_dmabuf_binding * > net_devmem_bind_dmabuf(struct net_device *dev, void *vdev, > struct device *dma_dev, > enum dma_data_direction direction, > - unsigned int dmabuf_fd, struct netdev_nl_sock *priv, > + unsigned int dmabuf_fd, unsigned int niov_shift, > + struct netdev_nl_sock *priv, > struct netlink_ext_ack *extack); > struct net_devmem_dmabuf_binding *net_devmem_lookup_dmabuf(u32 id); > void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding); > @@ -122,10 +125,11 @@ static inline u32 net_devmem_iov_binding_id(const > struct net_iov *niov) > > static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov) > { > - struct net_iov_area *owner = net_iov_owner(niov); > + struct dmabuf_genpool_chunk_owner *co = > + net_devmem_iov_to_chunk_owner(niov); > > - return owner->base_virtual + > - ((unsigned long)net_iov_idx(niov) << PAGE_SHIFT); > + return net_iov_owner(niov)->base_virtual + > + ((unsigned long)net_iov_idx(niov) << co->binding->niov_shift); > } > > static inline bool > @@ -175,6 +179,7 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev, > struct device *dma_dev, > enum dma_data_direction direction, > unsigned int dmabuf_fd, > + unsigned int niov_shift, > struct netdev_nl_sock *priv, > struct netlink_ext_ack *extack) > { > diff --git a/net/core/netdev-genl-gen.c b/net/core/netdev-genl-gen.c > index d18c89b5a6c7..447ed06d8c74 100644 > --- a/net/core/netdev-genl-gen.c > +++ b/net/core/netdev-genl-gen.c > @@ -106,10 +106,11 @@ static const struct nla_policy > netdev_qstats_get_nl_policy[NETDEV_A_QSTATS_SCOPE > }; > > /* NETDEV_CMD_BIND_RX - do */ > -static const struct nla_policy netdev_bind_rx_nl_policy[NETDEV_A_DMABUF_FD + > 1] = { > +static const struct nla_policy > netdev_bind_rx_nl_policy[NETDEV_A_DMABUF_RX_BUF_SIZE + 1] = { > [NETDEV_A_DMABUF_IFINDEX] = NLA_POLICY_MIN(NLA_U32, 1), > [NETDEV_A_DMABUF_FD] = { .type = NLA_U32, }, > [NETDEV_A_DMABUF_QUEUES] = NLA_POLICY_NESTED(netdev_queue_id_nl_policy), > + [NETDEV_A_DMABUF_RX_BUF_SIZE] = { .type = NLA_U32, }, > }; > > /* NETDEV_CMD_NAPI_SET - do */ > @@ -219,7 +220,7 @@ static const struct genl_split_ops netdev_nl_ops[] = { > .cmd = NETDEV_CMD_BIND_RX, > .doit = netdev_nl_bind_rx_doit, > .policy = netdev_bind_rx_nl_policy, > - .maxattr = NETDEV_A_DMABUF_FD, > + .maxattr = NETDEV_A_DMABUF_RX_BUF_SIZE, > .flags = GENL_UNS_ADMIN_PERM | GENL_CMD_CAP_DO, > }, > { > diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c > index b4d48f3672a5..8709e9c94389 100644 > --- a/net/core/netdev-genl.c > +++ b/net/core/netdev-genl.c > @@ -1012,6 +1012,7 @@ int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct > genl_info *info) > { > struct net_devmem_dmabuf_binding *binding; > u32 ifindex, dmabuf_fd, rxq_idx; > + unsigned int niov_shift = PAGE_SHIFT;
nit: keep the Christmas tree? With that addressed: Acked-by: Stanislav Fomichev <[email protected]>
