Messages in this thread | | | Subject | Re: [PATCH RFC 1/1] genirq: Make threaded handler use irq affinity for managed interrupt | From | John Garry <> | Date | Wed, 11 Dec 2019 17:09:18 +0000 |
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On 10/12/2019 01:43, Ming Lei wrote: >>>> For when the interrupt is managed, allow the threaded part to run on all >>>> cpus in the irq affinity mask. >>> I remembered that performance drop is observed by this approach in some >>> test. >> From checking the thread about the NVMe interrupt swamp, just switching to >> threaded handler alone degrades performance. I didn't see any specific >> results for this change from Long Li -https://lkml.org/lkml/2019/8/21/128
Hi Ming,
> I am pretty clear the reason for Azure, which is caused by aggressive interrupt > coalescing, and this behavior shouldn't be very common, and it can be > addressed by the following patch:
I am running some NVMe perf tests with Marc's patch.
I see this almost always eventually (with or without that patch):
[ 66.018140] rcu: INFO: rcu_preempt self-detected stall on CPU2% done] [5058MB/0KB/0KB /s] [1295K/0/0 iops] [eta 01m:39s] [ 66.023885] rcu: 12-....: (5250 ticks this GP) idle=182/1/0x4000000000000004 softirq=517/517 fqs=2529 [ 66.033306] (t=5254 jiffies g=733 q=2241) [ 66.037394] Task dump for CPU 12: [ 66.040696] fio R running task 0 798 796 0x00000002 [ 66.047733] Call trace: [ 66.050173] dump_backtrace+0x0/0x1a0 [ 66.053823] show_stack+0x14/0x20 [ 66.057126] sched_show_task+0x164/0x1a0 [ 66.061036] dump_cpu_task+0x40/0x2e8 [ 66.064686] rcu_dump_cpu_stacks+0xa0/0xe0 [ 66.068769] rcu_sched_clock_irq+0x6d8/0xaa8 [ 66.073027] update_process_times+0x2c/0x50 [ 66.077198] tick_sched_handle.isra.14+0x30/0x50 [ 66.081802] tick_sched_timer+0x48/0x98 [ 66.085625] __hrtimer_run_queues+0x120/0x1b8 [ 66.089968] hrtimer_interrupt+0xd4/0x250 [ 66.093966] arch_timer_handler_phys+0x28/0x40 [ 66.098398] handle_percpu_devid_irq+0x80/0x140 [ 66.102915] generic_handle_irq+0x24/0x38 [ 66.106911] __handle_domain_irq+0x5c/0xb0 [ 66.110995] gic_handle_irq+0x5c/0x148 [ 66.114731] el1_irq+0xb8/0x180 [ 66.117858] efi_header_end+0x94/0x234 [ 66.121595] irq_exit+0xd0/0xd8 [ 66.124724] __handle_domain_irq+0x60/0xb0 [ 66.128806] gic_handle_irq+0x5c/0x148 [ 66.132542] el0_irq_naked+0x4c/0x54 [ 97.152870] rcu: INFO: rcu_preempt self-detected stall on CPU8% done] [4736MB/0KB/0KB /s] [1212K/0/0 iops] [eta 01m:08s] [ 97.158616] rcu: 8-....: (1 GPs behind) idle=08e/1/0x4000000000000002 softirq=462/505 fqs=2621 [ 97.167414] (t=5253 jiffies g=737 q=5507) [ 97.171498] Task dump for CPU 8: [pu_task+0x40/0x2e8 [ 97.198705] rcu_dump_cpu_stacks+0xa0/0xe0 [ 97.202788] rcu_sched_clock_irq+0x6d8/0xaa8 [ 97.207046] update_process_times+0x2c/0x50 [ 97.211217] tick_sched_handle.isra.14+0x30/0x50 [ 97.215820] tick_sched_timer+0x48/0x98 [ 97.219644] __hrtimer_run_queues+0x120/0x1b8 [ 97.223989] hrtimer_interrupt+0xd4/0x250 [ 97.227987] arch_timer_handler_phys+0x28/0x40 [ 97.232418] handle_percpu_devid_irq+0x80/0x140 [ 97.236935] generic_handle_irq+0x24/0x38 [ 97.240931] __handle_domain_irq+0x5c/0xb0 [ 97.245015] gic_handle_irq+0x5c/0x148 [ 97.248751] el1_irq+0xb8/0x180 [ 97.251880] find_busiest_group+0x18c/0x9e8 [ 97.256050] load_balance+0x154/0xb98 [ 97.259700] rebalance_domains+0x1cc/0x2f8 [ 97.263783] run_rebalance_domains+0x78/0xe0 [ 97.268040] efi_header_end+0x114/0x234 [ 97.271864] run_ksoftirqd+0x38/0x48 [ 97.275427] smpboot_thread_fn+0x16c/0x270 [ 97.279511] kthread+0x118/0x120 [ 97.282726] ret_from_fork+0x10/0x18 [ 97.286289] Task dump for CPU 12: [ 97.289591] kworker/12:1 R running task 0 570 2 0x0000002a [ 97.296634] Workqueue: 0x0 (mm_percpu_wq) [ 97.300718] Call trace: [ 97.303152] __switch_to+0xbc/0x218 [ 97.306632] page_wait_table+0x1500/0x1800
Would this be the same interrupt "swamp" issue?
> > http://lists.infradead.org/pipermail/linux-nvme/2019-November/028008.html >
What is the status of these patches? I did not see them in mainline.
> Then please share your lockup story, such as, which HBA/drivers, test steps, > if you complete IOs from multiple disks(LUNs) on single CPU, if you have > multiple queues, how many active LUNs involved in the test, ... > >
Thanks, John
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