Re: [EXTERNAL] [PATCH 3/3] net: mana: add a function to spread IRQs per CPUs
From: Yury Norov
Date: Tue Dec 19 2023 - 09:05:00 EST
On Tue, Dec 19, 2023 at 10:18:49AM +0000, Souradeep Chakrabarti wrote:
>
>
> >-----Original Message-----
> >From: Yury Norov <yury.norov@xxxxxxxxx>
> >Sent: Monday, December 18, 2023 3:02 AM
> >To: Souradeep Chakrabarti <schakrabarti@xxxxxxxxxxxxxxxxxxx>; KY Srinivasan
> ><kys@xxxxxxxxxxxxx>; Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>;
> >wei.liu@xxxxxxxxxx; Dexuan Cui <decui@xxxxxxxxxxxxx>; davem@xxxxxxxxxxxxx;
> >edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx; pabeni@xxxxxxxxxx; Long Li
> ><longli@xxxxxxxxxxxxx>; yury.norov@xxxxxxxxx; leon@xxxxxxxxxx;
> >cai.huoqing@xxxxxxxxx; ssengar@xxxxxxxxxxxxxxxxxxx; vkuznets@xxxxxxxxxx;
> >tglx@xxxxxxxxxxxxx; linux-hyperv@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-
> >kernel@xxxxxxxxxxxxxxx; linux-rdma@xxxxxxxxxxxxxxx
> >Cc: Souradeep Chakrabarti <schakrabarti@xxxxxxxxxxxxx>; Paul Rosswurm
> ><paulros@xxxxxxxxxxxxx>
> >Subject: [EXTERNAL] [PATCH 3/3] net: mana: add a function to spread IRQs per
> >CPUs
> >
> >[Some people who received this message don't often get email from
> >yury.norov@xxxxxxxxx. Learn why this is important at
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> >
> >Souradeep investigated that the driver performs faster if IRQs are spread on CPUs
> >with the following heuristics:
> >
> >1. No more than one IRQ per CPU, if possible; 2. NUMA locality is the second
> >priority; 3. Sibling dislocality is the last priority.
> >
> >Let's consider this topology:
> >
> >Node 0 1
> >Core 0 1 2 3
> >CPU 0 1 2 3 4 5 6 7
> >
> >The most performant IRQ distribution based on the above topology and heuristics
> >may look like this:
> >
> >IRQ Nodes Cores CPUs
> >0 1 0 0-1
> >1 1 1 2-3
> >2 1 0 0-1
> >3 1 1 2-3
> >4 2 2 4-5
> >5 2 3 6-7
> >6 2 2 4-5
> >7 2 3 6-7
> >
> >The irq_setup() routine introduced in this patch leverages the
> >for_each_numa_hop_mask() iterator and assigns IRQs to sibling groups as
> >described above.
> >
> >According to [1], for NUMA-aware but sibling-ignorant IRQ distribution based on
> >cpumask_local_spread() performance test results look like this:
> >
> >./ntttcp -r -m 16
> >NTTTCP for Linux 1.4.0
> >---------------------------------------------------------
> >08:05:20 INFO: 17 threads created
> >08:05:28 INFO: Network activity progressing...
> >08:06:28 INFO: Test run completed.
> >08:06:28 INFO: Test cycle finished.
> >08:06:28 INFO: ##### Totals: #####
> >08:06:28 INFO: test duration :60.00 seconds
> >08:06:28 INFO: total bytes :630292053310
> >08:06:28 INFO: throughput :84.04Gbps
> >08:06:28 INFO: retrans segs :4
> >08:06:28 INFO: cpu cores :192
> >08:06:28 INFO: cpu speed :3799.725MHz
> >08:06:28 INFO: user :0.05%
> >08:06:28 INFO: system :1.60%
> >08:06:28 INFO: idle :96.41%
> >08:06:28 INFO: iowait :0.00%
> >08:06:28 INFO: softirq :1.94%
> >08:06:28 INFO: cycles/byte :2.50
> >08:06:28 INFO: cpu busy (all) :534.41%
> >
> >For NUMA- and sibling-aware IRQ distribution, the same test works 15% faster:
> >
> >./ntttcp -r -m 16
> >NTTTCP for Linux 1.4.0
> >---------------------------------------------------------
> >08:08:51 INFO: 17 threads created
> >08:08:56 INFO: Network activity progressing...
> >08:09:56 INFO: Test run completed.
> >08:09:56 INFO: Test cycle finished.
> >08:09:56 INFO: ##### Totals: #####
> >08:09:56 INFO: test duration :60.00 seconds
> >08:09:56 INFO: total bytes :741966608384
> >08:09:56 INFO: throughput :98.93Gbps
> >08:09:56 INFO: retrans segs :6
> >08:09:56 INFO: cpu cores :192
> >08:09:56 INFO: cpu speed :3799.791MHz
> >08:09:56 INFO: user :0.06%
> >08:09:56 INFO: system :1.81%
> >08:09:56 INFO: idle :96.18%
> >08:09:56 INFO: iowait :0.00%
> >08:09:56 INFO: softirq :1.95%
> >08:09:56 INFO: cycles/byte :2.25
> >08:09:56 INFO: cpu busy (all) :569.22%
> >
> >[1]
> >https://lore.kernel/
> >.org%2Fall%2F20231211063726.GA4977%40linuxonhyperv3.guj3yctzbm1etfxqx2v
> >ob5hsef.xx.internal.cloudapp.net%2F&data=05%7C02%7Cschakrabarti%40micros
> >oft.com%7Ca385a5a5d661458219c208dbff47a7ab%7C72f988bf86f141af91ab2d7
> >cd011db47%7C1%7C0%7C638384455520036393%7CUnknown%7CTWFpbGZsb3d
> >8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%
> >7C3000%7C%7C%7C&sdata=kzoalzSu6frB0GIaUM5VWsz04%2FsB%2FBdXwXKb26
> >IhqkE%3D&reserved=0
> >
> >Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>
> >Co-developed-by: Souradeep Chakrabarti <schakrabarti@xxxxxxxxxxxxxxxxxxx>
> >---
> > .../net/ethernet/microsoft/mana/gdma_main.c | 28 +++++++++++++++++++
> > 1 file changed, 28 insertions(+)
> >
> >diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> >b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> >index 6367de0c2c2e..11e64e42e3b2 100644
> >--- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> >+++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> >@@ -1243,6 +1243,34 @@ void mana_gd_free_res_map(struct gdma_resource
> >*r)
> > r->size = 0;
> > }
> >
> >+static __maybe_unused int irq_setup(unsigned int *irqs, unsigned int
> >+len, int node) {
> >+ const struct cpumask *next, *prev = cpu_none_mask;
> >+ cpumask_var_t cpus __free(free_cpumask_var);
> >+ int cpu, weight;
> >+
> >+ if (!alloc_cpumask_var(&cpus, GFP_KERNEL))
> >+ return -ENOMEM;
> >+
> >+ rcu_read_lock();
> >+ for_each_numa_hop_mask(next, node) {
> >+ weight = cpumask_weight_andnot(next, prev);
> >+ while (weight-- > 0) {
> Make it while (weight > 0) {
> >+ cpumask_andnot(cpus, next, prev);
> >+ for_each_cpu(cpu, cpus) {
> >+ if (len-- == 0)
> >+ goto done;
> >+ irq_set_affinity_and_hint(*irqs++,
> >topology_sibling_cpumask(cpu));
> >+ cpumask_andnot(cpus, cpus, topology_sibling_cpumask(cpu));
> Here do --weight, else this code will traverse the same node N^2 times, where each
> node has N cpus .
Sure.
When building your series on top of this, can you please fix it
inplace?
Thanks,
Yury
> >+ }
> >+ }
> >+ prev = next;
> >+ }
> >+done:
> >+ rcu_read_unlock();
> >+ return 0;
> >+}
> >+
> > static int mana_gd_setup_irqs(struct pci_dev *pdev) {
> > unsigned int max_queues_per_port = num_online_cpus();
> >--
> >2.40.1