From 7f6c553902bfa1c4e3f6cfa955c5ea036c7fe8e4 Mon Sep 17 00:00:00 2001 From: "Guilherme G. Piccoli" Date: Mon, 27 Jun 2016 12:16:43 -0300 Subject: [PATCH] i40e: use valid online CPU on q_vector initialization Currently, the q_vector initialization routine sets the affinity_mask of a q_vector based on v_idx value. Meaning a loop iterates on v_idx, which is an incremental value, and the cpumask is created based on this value. This is a problem in systems with multiple logical CPUs per core (like in SMT scenarios). If we disable some logical CPUs, by turning SMT off for example, we will end up with a sparse cpu_online_mask, i.e., only the first CPU in a core is online, and incremental filling in q_vector cpumask might lead to multiple offline CPUs being assigned to q_vectors. Example: if we have a system with 8 cores each one containing 8 logical CPUs (SMT == 8 in this case), we have 64 CPUs in total. But if SMT is disabled, only the 1st CPU in each core remains online, so the cpu_online_mask in this case would have only 8 bits set, in a sparse way. In general case, when SMT is off the cpu_online_mask has only C bits set: 0, 1*N, 2*N, ..., C*(N-1) where C == # of cores; N == # of logical CPUs per core. In our example, only bits 0, 8, 16, 24, 32, 40, 48, 56 would be set. This patch changes the way q_vector's affinity_mask is created: it iterates on v_idx, but consumes the CPU index from the cpu_online_mask instead of just using the v_idx incremental value. No functional changes were introduced. Signed-off-by: Guilherme G Piccoli Tested-by: Andrew Bowers Signed-off-by: Jeff Kirsher --- drivers/net/ethernet/intel/i40e/i40e_main.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c index 1592dcbed790..501f15d9f4d6 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_main.c +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c @@ -7721,10 +7721,11 @@ static int i40e_init_msix(struct i40e_pf *pf) * i40e_vsi_alloc_q_vector - Allocate memory for a single interrupt vector * @vsi: the VSI being configured * @v_idx: index of the vector in the vsi struct + * @cpu: cpu to be used on affinity_mask * * We allocate one q_vector. If allocation fails we return -ENOMEM. **/ -static int i40e_vsi_alloc_q_vector(struct i40e_vsi *vsi, int v_idx) +static int i40e_vsi_alloc_q_vector(struct i40e_vsi *vsi, int v_idx, int cpu) { struct i40e_q_vector *q_vector; @@ -7735,7 +7736,8 @@ static int i40e_vsi_alloc_q_vector(struct i40e_vsi *vsi, int v_idx) q_vector->vsi = vsi; q_vector->v_idx = v_idx; - cpumask_set_cpu(v_idx, &q_vector->affinity_mask); + cpumask_set_cpu(cpu, &q_vector->affinity_mask); + if (vsi->netdev) netif_napi_add(vsi->netdev, &q_vector->napi, i40e_napi_poll, NAPI_POLL_WEIGHT); @@ -7759,8 +7761,7 @@ static int i40e_vsi_alloc_q_vector(struct i40e_vsi *vsi, int v_idx) static int i40e_vsi_alloc_q_vectors(struct i40e_vsi *vsi) { struct i40e_pf *pf = vsi->back; - int v_idx, num_q_vectors; - int err; + int err, v_idx, num_q_vectors, current_cpu; /* if not MSIX, give the one vector only to the LAN VSI */ if (pf->flags & I40E_FLAG_MSIX_ENABLED) @@ -7770,10 +7771,15 @@ static int i40e_vsi_alloc_q_vectors(struct i40e_vsi *vsi) else return -EINVAL; + current_cpu = cpumask_first(cpu_online_mask); + for (v_idx = 0; v_idx < num_q_vectors; v_idx++) { - err = i40e_vsi_alloc_q_vector(vsi, v_idx); + err = i40e_vsi_alloc_q_vector(vsi, v_idx, current_cpu); if (err) goto err_out; + current_cpu = cpumask_next(current_cpu, cpu_online_mask); + if (unlikely(current_cpu >= nr_cpu_ids)) + current_cpu = cpumask_first(cpu_online_mask); } return 0; -- 2.20.1