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Message-ID: <ZXMiOwK3sOJNXHxd@yury-ThinkPad>
Date: Fri, 8 Dec 2023 06:03:39 -0800
From: Yury Norov <yury.norov@...il.com>
To: Souradeep Chakrabarti <schakrabarti@...ux.microsoft.com>
Cc: kys@...rosoft.com, haiyangz@...rosoft.com, wei.liu@...nel.org,
decui@...rosoft.com, davem@...emloft.net, edumazet@...gle.com,
kuba@...nel.org, pabeni@...hat.com, longli@...rosoft.com,
leon@...nel.org, cai.huoqing@...ux.dev, ssengar@...ux.microsoft.com,
vkuznets@...hat.com, tglx@...utronix.de,
linux-hyperv@...r.kernel.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-rdma@...r.kernel.org,
schakrabarti@...rosoft.com, paulros@...rosoft.com
Subject: Re: [PATCH V5 net-next] net: mana: Assigning IRQ affinity on HT cores
On Fri, Dec 08, 2023 at 02:02:34AM -0800, Souradeep Chakrabarti wrote:
> Existing MANA design assigns IRQ to every CPU, including sibling
> hyper-threads. This may cause multiple IRQs to be active simultaneously
> in the same core and may reduce the network performance with RSS.
Can you add an IRQ distribution diagram to compare before/after
behavior, similarly to what I did in the other email?
> Improve the performance by assigning IRQ to non sibling CPUs in local
> NUMA node. The performance improvement we are getting using ntttcp with
> following patch is around 15 percent with existing design and approximately
> 11 percent, when trying to assign one IRQ in each core across NUMA nodes,
> if enough cores are present.
How did you measure it? In the other email you said you used perf, can
you show your procedure in details?
> Suggested-by: Yury Norov <yury.norov@...li.com>
> Signed-off-by: Souradeep Chakrabarti <schakrabarti@...ux.microsoft.com>
> ---
[...]
> .../net/ethernet/microsoft/mana/gdma_main.c | 92 +++++++++++++++++--
> 1 file changed, 83 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> index 6367de0c2c2e..18e8908c5d29 100644
> --- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> +++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> @@ -1243,15 +1243,56 @@ void mana_gd_free_res_map(struct gdma_resource *r)
> r->size = 0;
> }
>
> +static int irq_setup(int *irqs, int nvec, int start_numa_node)
> +{
> + int w, cnt, cpu, err = 0, i = 0;
> + int next_node = start_numa_node;
What for this?
> + const struct cpumask *next, *prev = cpu_none_mask;
> + cpumask_var_t curr, cpus;
> +
> + if (!zalloc_cpumask_var(&curr, GFP_KERNEL)) {
> + err = -ENOMEM;
> + return err;
> + }
> + if (!zalloc_cpumask_var(&cpus, GFP_KERNEL)) {
free(curr);
> + err = -ENOMEM;
> + return err;
> + }
> +
> + rcu_read_lock();
> + for_each_numa_hop_mask(next, next_node) {
> + cpumask_andnot(curr, next, prev);
> + for (w = cpumask_weight(curr), cnt = 0; cnt < w; ) {
> + cpumask_copy(cpus, curr);
> + for_each_cpu(cpu, cpus) {
> + irq_set_affinity_and_hint(irqs[i], topology_sibling_cpumask(cpu));
> + if (++i == nvec)
> + goto done;
Think what if you're passed with irq_setup(NULL, 0, 0).
That's why I suggested to place this check at the beginning.
> + cpumask_andnot(cpus, cpus, topology_sibling_cpumask(cpu));
> + ++cnt;
> + }
> + }
> + prev = next;
> + }
> +done:
> + rcu_read_unlock();
> + free_cpumask_var(curr);
> + free_cpumask_var(cpus);
> + return err;
> +}
> +
> static int mana_gd_setup_irqs(struct pci_dev *pdev)
> {
> - unsigned int max_queues_per_port = num_online_cpus();
> struct gdma_context *gc = pci_get_drvdata(pdev);
> + unsigned int max_queues_per_port;
> struct gdma_irq_context *gic;
> unsigned int max_irqs, cpu;
> - int nvec, irq;
> + int start_irq_index = 1;
> + int nvec, *irqs, irq;
> int err, i = 0, j;
>
> + cpus_read_lock();
> + max_queues_per_port = num_online_cpus();
> if (max_queues_per_port > MANA_MAX_NUM_QUEUES)
> max_queues_per_port = MANA_MAX_NUM_QUEUES;
>
> @@ -1261,6 +1302,14 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
> nvec = pci_alloc_irq_vectors(pdev, 2, max_irqs, PCI_IRQ_MSIX);
> if (nvec < 0)
> return nvec;
> + if (nvec <= num_online_cpus())
> + start_irq_index = 0;
> +
> + irqs = kmalloc_array((nvec - start_irq_index), sizeof(int), GFP_KERNEL);
> + if (!irqs) {
> + err = -ENOMEM;
> + goto free_irq_vector;
> + }
>
> gc->irq_contexts = kcalloc(nvec, sizeof(struct gdma_irq_context),
> GFP_KERNEL);
> @@ -1287,21 +1336,44 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
> goto free_irq;
> }
>
> - err = request_irq(irq, mana_gd_intr, 0, gic->name, gic);
> - if (err)
> - goto free_irq;
> -
> - cpu = cpumask_local_spread(i, gc->numa_node);
> - irq_set_affinity_and_hint(irq, cpumask_of(cpu));
> + if (!i) {
> + err = request_irq(irq, mana_gd_intr, 0, gic->name, gic);
> + if (err)
> + goto free_irq;
> +
> + /* If number of IRQ is one extra than number of online CPUs,
> + * then we need to assign IRQ0 (hwc irq) and IRQ1 to
> + * same CPU.
> + * Else we will use different CPUs for IRQ0 and IRQ1.
> + * Also we are using cpumask_local_spread instead of
> + * cpumask_first for the node, because the node can be
> + * mem only.
> + */
> + if (start_irq_index) {
> + cpu = cpumask_local_spread(i, gc->numa_node);
I already mentioned that: if i == 0, you don't need to spread, just
pick 1st cpu from node.
> + irq_set_affinity_and_hint(irq, cpumask_of(cpu));
> + } else {
> + irqs[start_irq_index] = irq;
> + }
> + } else {
> + irqs[i - start_irq_index] = irq;
> + err = request_irq(irqs[i - start_irq_index], mana_gd_intr, 0,
> + gic->name, gic);
> + if (err)
> + goto free_irq;
> + }
> }
>
> + err = irq_setup(irqs, (nvec - start_irq_index), gc->numa_node);
> + if (err)
> + goto free_irq;
> err = mana_gd_alloc_res_map(nvec, &gc->msix_resource);
> if (err)
> goto free_irq;
>
> gc->max_num_msix = nvec;
> gc->num_msix_usable = nvec;
> -
> + cpus_read_unlock();
> return 0;
>
> free_irq:
> @@ -1314,8 +1386,10 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
> }
>
> kfree(gc->irq_contexts);
> + kfree(irqs);
> gc->irq_contexts = NULL;
> free_irq_vector:
> + cpus_read_unlock();
> pci_free_irq_vectors(pdev);
> return err;
> }
> --
> 2.34.1
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