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 <gpiccoli@linux.vnet.ibm.com> Tested-by: Andrew Bowers <andrewx.bowers@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
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@ -7721,10 +7721,11 @@ static int i40e_init_msix(struct i40e_pf *pf)
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* i40e_vsi_alloc_q_vector - Allocate memory for a single interrupt vector
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* @vsi: the VSI being configured
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* @v_idx: index of the vector in the vsi struct
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* @cpu: cpu to be used on affinity_mask
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*
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* We allocate one q_vector. If allocation fails we return -ENOMEM.
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**/
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static int i40e_vsi_alloc_q_vector(struct i40e_vsi *vsi, int v_idx)
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static int i40e_vsi_alloc_q_vector(struct i40e_vsi *vsi, int v_idx, int cpu)
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{
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struct i40e_q_vector *q_vector;
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@ -7735,7 +7736,8 @@ static int i40e_vsi_alloc_q_vector(struct i40e_vsi *vsi, int v_idx)
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q_vector->vsi = vsi;
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q_vector->v_idx = v_idx;
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cpumask_set_cpu(v_idx, &q_vector->affinity_mask);
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cpumask_set_cpu(cpu, &q_vector->affinity_mask);
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if (vsi->netdev)
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netif_napi_add(vsi->netdev, &q_vector->napi,
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i40e_napi_poll, NAPI_POLL_WEIGHT);
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@ -7759,8 +7761,7 @@ static int i40e_vsi_alloc_q_vector(struct i40e_vsi *vsi, int v_idx)
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static int i40e_vsi_alloc_q_vectors(struct i40e_vsi *vsi)
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{
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struct i40e_pf *pf = vsi->back;
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int v_idx, num_q_vectors;
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int err;
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int err, v_idx, num_q_vectors, current_cpu;
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/* if not MSIX, give the one vector only to the LAN VSI */
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if (pf->flags & I40E_FLAG_MSIX_ENABLED)
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@ -7770,10 +7771,15 @@ static int i40e_vsi_alloc_q_vectors(struct i40e_vsi *vsi)
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else
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return -EINVAL;
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current_cpu = cpumask_first(cpu_online_mask);
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for (v_idx = 0; v_idx < num_q_vectors; v_idx++) {
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err = i40e_vsi_alloc_q_vector(vsi, v_idx);
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err = i40e_vsi_alloc_q_vector(vsi, v_idx, current_cpu);
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if (err)
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goto err_out;
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current_cpu = cpumask_next(current_cpu, cpu_online_mask);
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if (unlikely(current_cpu >= nr_cpu_ids))
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current_cpu = cpumask_first(cpu_online_mask);
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}
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return 0;
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