linux-kernel - Re: [PATCH V3 3/5] genirq/affinity: add new callback for caculating set vectors

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Message-ID: <20190213151149.GD96272@google.com>
Date:   Wed, 13 Feb 2019 09:11:49 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Ming Lei <ming.lei@...hat.com>
Cc:     Christoph Hellwig <hch@....de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
        Sagi Grimberg <sagi@...mberg.me>,
        linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org, Keith Busch <keith.busch@...el.com>
Subject: Re: [PATCH V3 3/5] genirq/affinity: add new callback for caculating
 set vectors

On Wed, Feb 13, 2019 at 06:50:39PM +0800, Ming Lei wrote:
> Currently pre-caculated set vectors are provided by driver for
> allocating & spread vectors. This way only works when drivers passes
> same 'max_vecs' and 'min_vecs' to pci_alloc_irq_vectors_affinity(),
> also requires driver to retry the allocating & spread.

s/pre-caculated/precalculated/
s/drivers/a driver/
s/also requires/which also requires the/

> As Bjorn and Keith mentioned, the current usage & interface for irq sets
> is a bit awkward because the retrying should have been avoided by providing
> one resonable 'min_vecs'. However, if 'min_vecs' isn't same with
> 'max_vecs', number of the allocated vectors is unknown before calling
> pci_alloc_irq_vectors_affinity(), then each set's vectors can't be
> pre-caculated.

s/resonable/reasonable/
s/isn't same with/isn't the same as/
s/number of/the number of/
s/pre-caculated/precalculated/
s/then each/and the/
s/irq/IRQ/

> Add a new callback of .calc_sets into 'struct irq_affinity' so that
> driver can caculate set vectors after IRQ vector is allocated and
> before spread IRQ vectors. Add 'priv' so that driver may retrieve
> its private data via the 'struct irq_affinity'.

s/caculate/calculate/

I *think* "set vectors" here has something to do with an affinity
cpumask?  "Set vectors" doesn't seem like quite the right terminology.

> Suggested-by: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Ming Lei <ming.lei@...hat.com>
> ---
>  include/linux/interrupt.h | 4 ++++
>  kernel/irq/affinity.c     | 8 ++++++--
>  2 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
> index a20150627a32..7a27f6ba1f2f 100644
> --- a/include/linux/interrupt.h
> +++ b/include/linux/interrupt.h
> @@ -269,12 +269,16 @@ struct irq_affinity_notify {
>   *			the MSI(-X) vector space
>   * @nr_sets:		Length of passed in *sets array
>   * @set_vectors:	Number of affinitized sets
> + * @calc_sets:		Callback for caculating set vectors

Possible s/set vectors/<something else>/ ?

> + * @priv:		Private data of @calc_sets
>   */
>  struct irq_affinity {
>  	int	pre_vectors;
>  	int	post_vectors;
>  	int	nr_sets;
>  	int	set_vectors[IRQ_MAX_SETS];
> +	void	(*calc_sets)(struct irq_affinity *, int nvecs);
> +	void	*priv;
>  };
>  
>  /**
> diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
> index b868b9d3df7f..2341b1f005fa 100644
> --- a/kernel/irq/affinity.c
> +++ b/kernel/irq/affinity.c
> @@ -267,7 +267,9 @@ irq_create_affinity_masks(int nvecs, struct irq_affinity *affd)
>  	 * Spread on present CPUs starting from affd->pre_vectors. If we
>  	 * have multiple sets, build each sets affinity mask separately.
>  	 */
> -	if (!affd->nr_sets) {
> +	if (affd->calc_sets) {
> +		affd->calc_sets(affd, nvecs);
> +	} else if (!affd->nr_sets) {
>  		affd->nr_sets = 1;
>  		affd->set_vectors[0] = affvecs;
>  	}
> @@ -316,7 +318,9 @@ int irq_calc_affinity_vectors(int minvec, int maxvec, const struct irq_affinity
>  	if (resv > minvec)
>  		return 0;
>  
> -	if (affd->nr_sets) {
> +	if (affd->calc_sets) {
> +		set_vecs = vecs;
> +	} else if (affd->nr_sets) {
>  		int i;
>  
>  		for (i = 0, set_vecs = 0;  i < affd->nr_sets; i++)
> -- 
> 2.9.5
>