On Wed, Sep 1, 2021 at 6:12 PM <kerneljasonxing@xxxxxxxxx> wrote:
>
> From: Jason Xing <xingwanli@xxxxxxxxxxxx>
>
> Originally, ixgbe driver doesn't allow the mounting of xdpdrv if the
> server is equipped with more than 64 cpus online. So it turns out that
> the loading of xdpdrv causes the "NOMEM" failure.
>
> Actually, we can adjust the algorithm and then make it work through
> mapping the current cpu to some xdp ring with the protect of @tx_lock.
>
> Here're some numbers before/after applying this patch with xdp-example
> loaded on the eth0X:
>
> As client (tx path):
> Before After
> TCP_STREAM send-64 734.14 714.20
> TCP_STREAM send-128 1401.91 1395.05
> TCP_STREAM send-512 5311.67 5292.84
> TCP_STREAM send-1k 9277.40 9356.22 (not stable)
> TCP_RR send-1 22559.75 21844.22
> TCP_RR send-128 23169.54 22725.13
> TCP_RR send-512 21670.91 21412.56
>
> As server (rx path):
> Before After
> TCP_STREAM send-64 1416.49 1383.12
> TCP_STREAM send-128 3141.49 3055.50
> TCP_STREAM send-512 9488.73 9487.44
> TCP_STREAM send-1k 9491.17 9356.22 (not stable)
> TCP_RR send-1 23617.74 23601.60
> ...
>
> Notice: the TCP_RR mode is unstable as the official document explaines.
>
> I tested many times with different parameters combined through netperf.
> Though the result is not that accurate, I cannot see much influence on
> this patch. The static key is places on the hot path, but it actually
> shouldn't cause a huge regression theoretically.
>
> Fixes: 33fdc82f08 ("ixgbe: add support for XDP_TX action")
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Co-developed-by: Shujin Li <lishujin@xxxxxxxxxxxx>
> Signed-off-by: Shujin Li <lishujin@xxxxxxxxxxxx>
> Signed-off-by: Jason Xing <xingwanli@xxxxxxxxxxxx>
> ---
> v7:
> - Factorized to a single spin_lock/unlock in ixgbe_xdp_xmit() (Eric)
> - Handle other parts of lock/unlock in ixgbe_run_xdp()/_zc() (Jason)
>
Does this change make any sense? I think it is much clearer than the
v6 patch and they both have the same idea. Now I'm looking for more
advice :-)
Thanks,
Jason
> v6:
> - Move the declaration of static-key to the proper position (Test Robot)
> - Add reported-by tag (Jason)
> - Add more detailed performance test results (Jason)
>
> v5:
> - Change back to nr_cpu_ids (Eric)
>
> v4:
> - Update the wrong commit messages. (Jason)
>
> v3:
> - Change nr_cpu_ids to num_online_cpus() (Maciej)
> - Rename MAX_XDP_QUEUES to IXGBE_MAX_XDP_QS (Maciej)
> - Rename ixgbe_determine_xdp_cpu() to ixgbe_determine_xdp_q_idx() (Maciej)
> - Wrap ixgbe_xdp_ring_update_tail() with lock into one function (Maciej)
>
> v2:
> - Adjust cpu id in ixgbe_xdp_xmit(). (Jesper)
> - Add a fallback path. (Maciej)
> - Adjust other parts related to xdp ring.
> ---
> drivers/net/ethernet/intel/ixgbe/ixgbe.h | 23 +++++++++-
> drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c | 9 +++-
> drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 50 ++++++++++++++++------
> .../net/ethernet/intel/ixgbe/ixgbe_txrx_common.h | 3 +-
> drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 16 ++++---
> 5 files changed, 77 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
> index a604552..4a69823 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
> @@ -351,6 +351,7 @@ struct ixgbe_ring {
> };
> u16 rx_offset;
> struct xdp_rxq_info xdp_rxq;
> + spinlock_t tx_lock; /* used in XDP mode */
> struct xsk_buff_pool *xsk_pool;
> u16 ring_idx; /* {rx,tx,xdp}_ring back reference idx */
> u16 rx_buf_len;
> @@ -375,11 +376,13 @@ enum ixgbe_ring_f_enum {
> #define IXGBE_MAX_FCOE_INDICES 8
> #define MAX_RX_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
> #define MAX_TX_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
> -#define MAX_XDP_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
> +#define IXGBE_MAX_XDP_QS (IXGBE_MAX_FDIR_INDICES + 1)
> #define IXGBE_MAX_L2A_QUEUES 4
> #define IXGBE_BAD_L2A_QUEUE 3
> #define IXGBE_MAX_MACVLANS 63
>
> +DECLARE_STATIC_KEY_FALSE(ixgbe_xdp_locking_key);
> +
> struct ixgbe_ring_feature {
> u16 limit; /* upper limit on feature indices */
> u16 indices; /* current value of indices */
> @@ -629,7 +632,7 @@ struct ixgbe_adapter {
>
> /* XDP */
> int num_xdp_queues;
> - struct ixgbe_ring *xdp_ring[MAX_XDP_QUEUES];
> + struct ixgbe_ring *xdp_ring[IXGBE_MAX_XDP_QS];
> unsigned long *af_xdp_zc_qps; /* tracks AF_XDP ZC enabled rings */
>
> /* TX */
> @@ -772,6 +775,22 @@ struct ixgbe_adapter {
> #endif /* CONFIG_IXGBE_IPSEC */
> };
>
> +static inline int ixgbe_determine_xdp_q_idx(int cpu)
> +{
> + if (static_key_enabled(&ixgbe_xdp_locking_key))
> + return cpu % IXGBE_MAX_XDP_QS;
> + else
> + return cpu;
> +}
> +
> +static inline
> +struct ixgbe_ring *ixgbe_determine_xdp_ring(struct ixgbe_adapter *adapter)
> +{
> + int index = ixgbe_determine_xdp_q_idx(smp_processor_id());
> +
> + return adapter->xdp_ring[index];
> +}
> +
> static inline u8 ixgbe_max_rss_indices(struct ixgbe_adapter *adapter)
> {
> switch (adapter->hw.mac.type) {
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
> index 0218f6c..86b1116 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
> @@ -299,7 +299,10 @@ static void ixgbe_cache_ring_register(struct ixgbe_adapter *adapter)
>
> static int ixgbe_xdp_queues(struct ixgbe_adapter *adapter)
> {
> - return adapter->xdp_prog ? nr_cpu_ids : 0;
> + int queues;
> +
> + queues = min_t(int, IXGBE_MAX_XDP_QS, nr_cpu_ids);
> + return adapter->xdp_prog ? queues : 0;
> }
>
> #define IXGBE_RSS_64Q_MASK 0x3F
> @@ -947,6 +950,7 @@ static int ixgbe_alloc_q_vector(struct ixgbe_adapter *adapter,
> ring->count = adapter->tx_ring_count;
> ring->queue_index = xdp_idx;
> set_ring_xdp(ring);
> + spin_lock_init(&ring->tx_lock);
>
> /* assign ring to adapter */
> WRITE_ONCE(adapter->xdp_ring[xdp_idx], ring);
> @@ -1032,6 +1036,9 @@ static void ixgbe_free_q_vector(struct ixgbe_adapter *adapter, int v_idx)
> adapter->q_vector[v_idx] = NULL;
> __netif_napi_del(&q_vector->napi);
>
> + if (static_key_enabled(&ixgbe_xdp_locking_key))
> + static_branch_dec(&ixgbe_xdp_locking_key);
> +
> /*
> * after a call to __netif_napi_del() napi may still be used and
> * ixgbe_get_stats64() might access the rings on this vector,
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> index 14aea40..8b9e21b 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> @@ -165,6 +165,9 @@ static int ixgbe_notify_dca(struct notifier_block *, unsigned long event,
> MODULE_DESCRIPTION("Intel(R) 10 Gigabit PCI Express Network Driver");
> MODULE_LICENSE("GPL v2");
>
> +DEFINE_STATIC_KEY_FALSE(ixgbe_xdp_locking_key);
> +EXPORT_SYMBOL(ixgbe_xdp_locking_key);
> +
> static struct workqueue_struct *ixgbe_wq;
>
> static bool ixgbe_check_cfg_remove(struct ixgbe_hw *hw, struct pci_dev *pdev);
> @@ -2197,6 +2200,7 @@ static struct sk_buff *ixgbe_run_xdp(struct ixgbe_adapter *adapter,
> {
> int err, result = IXGBE_XDP_PASS;
> struct bpf_prog *xdp_prog;
> + struct ixgbe_ring *ring;
> struct xdp_frame *xdpf;
> u32 act;
>
> @@ -2215,7 +2219,12 @@ static struct sk_buff *ixgbe_run_xdp(struct ixgbe_adapter *adapter,
> xdpf = xdp_convert_buff_to_frame(xdp);
> if (unlikely(!xdpf))
> goto out_failure;
> - result = ixgbe_xmit_xdp_ring(adapter, xdpf);
> + ring = ixgbe_determine_xdp_ring(adapter);
> + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> + spin_lock(&ring->tx_lock);
> + result = ixgbe_xmit_xdp_ring(ring, xdpf);
> + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> + spin_unlock(&ring->tx_lock);
> if (result == IXGBE_XDP_CONSUMED)
> goto out_failure;
> break;
> @@ -2422,13 +2431,9 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
> xdp_do_flush_map();
>
> if (xdp_xmit & IXGBE_XDP_TX) {
> - struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
> + struct ixgbe_ring *ring = ixgbe_determine_xdp_ring(adapter);
>
> - /* Force memory writes to complete before letting h/w
> - * know there are new descriptors to fetch.
> - */
> - wmb();
> - writel(ring->next_to_use, ring->tail);
> + ixgbe_xdp_ring_update_tail_locked(ring);
> }
>
> u64_stats_update_begin(&rx_ring->syncp);
> @@ -6320,7 +6325,7 @@ static int ixgbe_sw_init(struct ixgbe_adapter *adapter,
> if (ixgbe_init_rss_key(adapter))
> return -ENOMEM;
>
> - adapter->af_xdp_zc_qps = bitmap_zalloc(MAX_XDP_QUEUES, GFP_KERNEL);
> + adapter->af_xdp_zc_qps = bitmap_zalloc(IXGBE_MAX_XDP_QS, GFP_KERNEL);
> if (!adapter->af_xdp_zc_qps)
> return -ENOMEM;
>
> @@ -8536,10 +8541,9 @@ static u16 ixgbe_select_queue(struct net_device *dev, struct sk_buff *skb,
> }
>
> #endif
> -int ixgbe_xmit_xdp_ring(struct ixgbe_adapter *adapter,
> +int ixgbe_xmit_xdp_ring(struct ixgbe_ring *ring,
> struct xdp_frame *xdpf)
> {
> - struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
> struct ixgbe_tx_buffer *tx_buffer;
> union ixgbe_adv_tx_desc *tx_desc;
> u32 len, cmd_type;
> @@ -10130,8 +10134,13 @@ static int ixgbe_xdp_setup(struct net_device *dev, struct bpf_prog *prog)
> return -EINVAL;
> }
>
> - if (nr_cpu_ids > MAX_XDP_QUEUES)
> + /* if the number of cpus is much larger than the maximum of queues,
> + * we should stop it and then return with NOMEM like before.
> + */
> + if (nr_cpu_ids > IXGBE_MAX_XDP_QS * 2)
> return -ENOMEM;
> + else if (nr_cpu_ids > IXGBE_MAX_XDP_QS)
> + static_branch_inc(&ixgbe_xdp_locking_key);
>
> old_prog = xchg(&adapter->xdp_prog, prog);
> need_reset = (!!prog != !!old_prog);
> @@ -10195,6 +10204,15 @@ void ixgbe_xdp_ring_update_tail(struct ixgbe_ring *ring)
> writel(ring->next_to_use, ring->tail);
> }
>
> +void ixgbe_xdp_ring_update_tail_locked(struct ixgbe_ring *ring)
> +{
> + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> + spin_lock(&ring->tx_lock);
> + ixgbe_xdp_ring_update_tail(ring);
> + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> + spin_unlock(&ring->tx_lock);
> +}
> +
> static int ixgbe_xdp_xmit(struct net_device *dev, int n,
> struct xdp_frame **frames, u32 flags)
> {
> @@ -10212,18 +10230,21 @@ static int ixgbe_xdp_xmit(struct net_device *dev, int n,
> /* During program transitions its possible adapter->xdp_prog is assigned
> * but ring has not been configured yet. In this case simply abort xmit.
> */
> - ring = adapter->xdp_prog ? adapter->xdp_ring[smp_processor_id()] : NULL;
> + ring = adapter->xdp_prog ? ixgbe_determine_xdp_ring(adapter) : NULL;
> if (unlikely(!ring))
> return -ENXIO;
>
> if (unlikely(test_bit(__IXGBE_TX_DISABLED, &ring->state)))
> return -ENXIO;
>
> + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> + spin_lock(&ring->tx_lock);
> +
> for (i = 0; i < n; i++) {
> struct xdp_frame *xdpf = frames[i];
> int err;
>
> - err = ixgbe_xmit_xdp_ring(adapter, xdpf);
> + err = ixgbe_xmit_xdp_ring(ring, xdpf);
> if (err != IXGBE_XDP_TX)
> break;
> nxmit++;
> @@ -10232,6 +10253,9 @@ static int ixgbe_xdp_xmit(struct net_device *dev, int n,
> if (unlikely(flags & XDP_XMIT_FLUSH))
> ixgbe_xdp_ring_update_tail(ring);
>
> + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> + spin_unlock(&ring->tx_lock);
> +
> return nxmit;
> }
>
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h b/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
> index 2aeec78..a82533f 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
> @@ -12,7 +12,7 @@
> #define IXGBE_TXD_CMD (IXGBE_TXD_CMD_EOP | \
> IXGBE_TXD_CMD_RS)
>
> -int ixgbe_xmit_xdp_ring(struct ixgbe_adapter *adapter,
> +int ixgbe_xmit_xdp_ring(struct ixgbe_ring *ring,
> struct xdp_frame *xdpf);
> bool ixgbe_cleanup_headers(struct ixgbe_ring *rx_ring,
> union ixgbe_adv_rx_desc *rx_desc,
> @@ -23,6 +23,7 @@ void ixgbe_process_skb_fields(struct ixgbe_ring *rx_ring,
> void ixgbe_rx_skb(struct ixgbe_q_vector *q_vector,
> struct sk_buff *skb);
> void ixgbe_xdp_ring_update_tail(struct ixgbe_ring *ring);
> +void ixgbe_xdp_ring_update_tail_locked(struct ixgbe_ring *ring);
> void ixgbe_irq_rearm_queues(struct ixgbe_adapter *adapter, u64 qmask);
>
> void ixgbe_txrx_ring_disable(struct ixgbe_adapter *adapter, int ring);
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
> index b1d22e4..db2bc58 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
> @@ -100,6 +100,7 @@ static int ixgbe_run_xdp_zc(struct ixgbe_adapter *adapter,
> {
> int err, result = IXGBE_XDP_PASS;
> struct bpf_prog *xdp_prog;
> + struct ixgbe_ring *ring;
> struct xdp_frame *xdpf;
> u32 act;
>
> @@ -120,7 +121,12 @@ static int ixgbe_run_xdp_zc(struct ixgbe_adapter *adapter,
> xdpf = xdp_convert_buff_to_frame(xdp);
> if (unlikely(!xdpf))
> goto out_failure;
> - result = ixgbe_xmit_xdp_ring(adapter, xdpf);
> + ring = ixgbe_determine_xdp_ring(adapter);
> + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> + spin_lock(&ring->tx_lock);
> + result = ixgbe_xmit_xdp_ring(ring, xdpf);
> + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> + spin_unlock(&ring->tx_lock);
> if (result == IXGBE_XDP_CONSUMED)
> goto out_failure;
> break;
> @@ -334,13 +340,9 @@ int ixgbe_clean_rx_irq_zc(struct ixgbe_q_vector *q_vector,
> xdp_do_flush_map();
>
> if (xdp_xmit & IXGBE_XDP_TX) {
> - struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
> + struct ixgbe_ring *ring = ixgbe_determine_xdp_ring(adapter);
>
> - /* Force memory writes to complete before letting h/w
> - * know there are new descriptors to fetch.
> - */
> - wmb();
> - writel(ring->next_to_use, ring->tail);
> + ixgbe_xdp_ring_update_tail_locked(ring);
> }
>
> u64_stats_update_begin(&rx_ring->syncp);
> --
> 1.8.3.1
>
