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Message-ID: <CAL2rwxq8kKMtPY6SvWzMCUUfYGSJyjjSFCKu4zvLpRyWvQtWNw@mail.gmail.com>
Date: Wed, 19 Dec 2018 18:25:44 +0530
From: Sumit Saxena <sumit.saxena@...adcom.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: douliyangs@...il.com, LKML <linux-kernel@...r.kernel.org>,
linux-pci@...r.kernel.org,
Kashyap Desai <kashyap.desai@...adcom.com>,
Shivasharan Srikanteshwara
<shivasharan.srikanteshwara@...adcom.com>,
Ming Lei <ming.lei@...hat.com>, Christoph Hellwig <hch@....de>,
Bjorn Helgaas <bhelgaas@...gle.com>, douliyang1@...wei.com
Subject: Re: [PATCH 0/3] irq/core: Fix and expand the irq affinity descriptor
On Wed, Dec 19, 2018 at 4:23 PM Thomas Gleixner <tglx@...utronix.de> wrote:
>
> On Tue, 4 Dec 2018, Dou Liyang wrote:
>
> > Now, Spreading the interrupt affinity info by a cpumask pointer is not
> > enough, meets a problem[1] and hard to expand in the future.
> >
> > Fix it by:
> >
> > +-----------------------------------+
> > | |
> > | struct cpumask *affinity |
> > | |
> > +-----------------------------------+
> > |
> > +------------------v-------------------+
> > | |
> > | struct irq_affinity_desc { |
> > | struct cpumask mask; |
> > | unsigned int is_managed : 1; |
> > | }; |
> > | |
> > +--------------------------------------+
> >
>
> So, I've applied that lot for 4.21 (or whatever number it will be). That's
> only the first step for solving Kashyap's problem.
>
> IIRC, then Kashap wanted to get initial interrupt spreading for these extra
> magic interrupts as well, but not have them marked managed.
>
> That's trivial to do now with the two queued changes in that area:
>
> - The rework above
>
> - The support for interrupt sets from Jens
>
> Just adding a small bitfield to struct irq_affinity which allows to tell
> the core that a particular interrupt set is not managed does the trick.
>
> Untested patch below.
>
> Kashyap, is that what you were looking for and if so, does it work?
Thomas,
We could not test these patches as they did net get applied to latest
linux-block tree cleanly.
Our requirement is: 1. extra interrupts should be un-managed and 2.
should be spread to CPUs of local NUMA node.
If interrupts are un-managed but not spread as per our requirement,
then still driver/userspace apps can manage by spreading
them as required by calling API- irq_set_affinity_hint().
Thanks,
Sumit
>
> Thanks,
>
> tglx
>
> 8<-----------------
>
> Subject: genirq/affinity: Add support for non-managed affinity sets
> From: Thomas Gleixner <tglx@...utronix.de>
> Date: Tue, 18 Dec 2018 16:46:47 +0100
>
> Some drivers need an extra set of interrupts which are not marked managed,
> but should get initial interrupt spreading.
>
> Add a bitmap to struct irq_affinity which allows the driver to mark a
> particular set of interrupts as non managed. Check the bitmap during
> spreading and use the result to mark the interrupts in the sets
> accordingly.
>
> The unmanaged interrupts get initial spreading, but user space can change
> their affinity later on.
>
> Usage example:
>
> struct irq_affinity affd = { .pre_vectors = 2 };
> int sets[2];
>
> /* Fill in sets[] */
>
> affd.nr_sets = 2;
> affd.sets = &sets;
> affd.unmanaged_sets = 0x02;
>
> ......
>
> So both sets are properly spread out, but the second set is not marked
> managed.
>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> ---
> include/linux/interrupt.h | 10 ++++++----
> kernel/irq/affinity.c | 24 ++++++++++++++----------
> 2 files changed, 20 insertions(+), 14 deletions(-)
>
> --- a/kernel/irq/affinity.c
> +++ b/kernel/irq/affinity.c
> @@ -99,7 +99,8 @@ static int __irq_build_affinity_masks(co
> cpumask_var_t *node_to_cpumask,
> const struct cpumask *cpu_mask,
> struct cpumask *nmsk,
> - struct irq_affinity_desc *masks)
> + struct irq_affinity_desc *masks,
> + bool managed)
> {
> int n, nodes, cpus_per_vec, extra_vecs, done = 0;
> int last_affv = firstvec + numvecs;
> @@ -154,6 +155,7 @@ static int __irq_build_affinity_masks(co
> }
> irq_spread_init_one(&masks[curvec].mask, nmsk,
> cpus_per_vec);
> + masks[curvec].is_managed = managed;
> }
>
> done += v;
> @@ -176,7 +178,8 @@ static int __irq_build_affinity_masks(co
> static int irq_build_affinity_masks(const struct irq_affinity *affd,
> int startvec, int numvecs, int firstvec,
> cpumask_var_t *node_to_cpumask,
> - struct irq_affinity_desc *masks)
> + struct irq_affinity_desc *masks,
> + bool managed)
> {
> int curvec = startvec, nr_present, nr_others;
> int ret = -ENOMEM;
> @@ -196,7 +199,8 @@ static int irq_build_affinity_masks(cons
> /* Spread on present CPUs starting from affd->pre_vectors */
> nr_present = __irq_build_affinity_masks(affd, curvec, numvecs,
> firstvec, node_to_cpumask,
> - cpu_present_mask, nmsk, masks);
> + cpu_present_mask, nmsk, masks,
> + managed);
>
> /*
> * Spread on non present CPUs starting from the next vector to be
> @@ -211,7 +215,7 @@ static int irq_build_affinity_masks(cons
> cpumask_andnot(npresmsk, cpu_possible_mask, cpu_present_mask);
> nr_others = __irq_build_affinity_masks(affd, curvec, numvecs,
> firstvec, node_to_cpumask,
> - npresmsk, nmsk, masks);
> + npresmsk, nmsk, masks, managed);
> put_online_cpus();
>
> if (nr_present < numvecs)
> @@ -268,10 +272,11 @@ irq_create_affinity_masks(int nvecs, con
>
> for (i = 0, usedvecs = 0; i < nr_sets; i++) {
> int this_vecs = affd->sets ? affd->sets[i] : affvecs;
> + bool managed = !test_bit(i, &affd->unmanaged_sets);
> int ret;
>
> - ret = irq_build_affinity_masks(affd, curvec, this_vecs,
> - curvec, node_to_cpumask, masks);
> + ret = irq_build_affinity_masks(affd, curvec, this_vecs, curvec,
> + node_to_cpumask, masks, managed);
> if (ret) {
> kfree(masks);
> masks = NULL;
> @@ -289,10 +294,6 @@ irq_create_affinity_masks(int nvecs, con
> for (; curvec < nvecs; curvec++)
> cpumask_copy(&masks[curvec].mask, irq_default_affinity);
>
> - /* Mark the managed interrupts */
> - for (i = affd->pre_vectors; i < nvecs - affd->post_vectors; i++)
> - masks[i].is_managed = 1;
> -
> outnodemsk:
> free_node_to_cpumask(node_to_cpumask);
> return masks;
> @@ -316,6 +317,9 @@ int irq_calc_affinity_vectors(int minvec
> if (affd->nr_sets) {
> int i;
>
> + if (WARN_ON_ONCE(affd->nr_sets > BITS_PER_LONG))
> + return 0;
> +
> for (i = 0, set_vecs = 0; i < affd->nr_sets; i++)
> set_vecs += affd->sets[i];
> } else {
> --- a/include/linux/interrupt.h
> +++ b/include/linux/interrupt.h
> @@ -249,12 +249,14 @@ struct irq_affinity_notify {
> * the MSI(-X) vector space
> * @nr_sets: Length of passed in *sets array
> * @sets: Number of affinitized sets
> + * @unmanaged_sets: Bitmap to mark members of @sets as unmanaged
> */
> struct irq_affinity {
> - int pre_vectors;
> - int post_vectors;
> - int nr_sets;
> - int *sets;
> + int pre_vectors;
> + int post_vectors;
> + int nr_sets;
> + int *sets;
> + unsigned long unmanaged_sets;
> };
>
> /**
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