Patchwork [V2,2/4] genirq/affinity: add new callback for caculating set vectors

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Submitter Ming Lei
Date Feb. 12, 2019, 1:04 p.m.
Message ID <20190212130439.14501-3-ming.lei@redhat.com>
Download mbox | patch
Permalink /patch/723895/
State New
Headers show

Comments

Ming Lei - Feb. 12, 2019, 1:04 p.m.
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.

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.

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'.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 include/linux/interrupt.h |  4 ++++
 kernel/irq/affinity.c     | 13 +++++++++----
 2 files changed, 13 insertions(+), 4 deletions(-)
Thomas Gleixner - Feb. 12, 2019, 1:37 p.m.
On Tue, 12 Feb 2019, 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.
> 
> 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.
> 
> 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'.

Nice changelog!

>  	 * Spread on present CPUs starting from affd->pre_vectors. If we
>  	 * have multiple sets, build each sets affinity mask separately.
>  	 */
> -	nr_sets = affd->nr_sets;
> -	if (!nr_sets) {
> +	if (affd->calc_sets) {
> +		affd->calc_sets(affd, nvecs);
> +		nr_sets = affd->nr_sets;
> +	} else if (!affd->nr_sets) {
>  		nr_sets = 1;
>  		affd->set_vectors[0] = affvecs;
> -	}
> +	} else
> +		nr_sets = affd->nr_sets;

Lacks curly brackets.

Aside of that it might make sense to get rid of the local variable, but
that should be done in patch 1 if at all. No strong opinion though.

Thanks,

	tglx

Patch

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
+ * @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 a97b7c33d2db..34abba63df4d 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -264,11 +264,14 @@  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.
 	 */
-	nr_sets = affd->nr_sets;
-	if (!nr_sets) {
+	if (affd->calc_sets) {
+		affd->calc_sets(affd, nvecs);
+		nr_sets = affd->nr_sets;
+	} else if (!affd->nr_sets) {
 		nr_sets = 1;
 		affd->set_vectors[0] = affvecs;
-	}
+	} else
+		nr_sets = affd->nr_sets;
 
 	for (i = 0, usedvecs = 0; i < nr_sets; i++) {
 		int this_vecs = affd->set_vectors[i];
@@ -314,7 +317,9 @@  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++)