From: Or Gerlitz <ogerl...@mellanox.com>
Date: Sun, 1 Nov 2015 19:35:18 +0200
> @@ -49,6 +50,15 @@ struct mlx5_cqe64 *mlx5e_get_cqe(struct mlx5e_cq *cq)
> return cqe;
> }
>
> +static inline bool mlx5e_no_channel_affinity_change(struct mlx5e_channel *c)
> +{
> + int current_cpu = smp_processor_id();
> + struct irq_data *d = irq_desc_get_irq_data(c->irq_desc);
> + struct cpumask *aff = irq_data_get_affinity_mask(d);
> +
> + return cpumask_test_cpu(current_cpu, aff);
> +}
This is so much pointer dereferencing and then a bitmask test as well.
Are you really sure sure an extremely rare situation warrants this
test every single NAPI poll call?
If this is a real problem, then every driver is susceptible to the
issue and it therefore warrants a generic solution. And if we have
generic infrastructure for this situation in the code NAPI polling
networking code, I guarantee that it will probably be implemented much
more cheaply than this.
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