From: Suzuki K Poulose <suzuki.poulose@arm.com>
To: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, mark.rutland@arm.com,
julien.thierry@arm.com, robin.murphy@arm.com
Subject: Re: [PATCH v5 0/7] arm64: perf: Support for chained counters
Date: Tue, 10 Jul 2018 16:01:35 +0100 [thread overview]
Message-ID: <50b0107c-b01d-956a-bd85-d588bf9869ee@arm.com> (raw)
In-Reply-To: <20180710143105.GC9022@arm.com>
On 07/10/2018 03:31 PM, Will Deacon wrote:
> Hi Suzuki,
>
> On Tue, Jul 10, 2018 at 09:57:57AM +0100, Suzuki K Poulose wrote:
>> This series adds support for counting PMU events using 64bit counters
>> for arm64 PMU.
>>
>> The Arm v8 PMUv3 supports combining two adjacent 32bit counters
>> (low even and hig odd counters) to count a given "event" in 64bit mode.
>> This series adds the support for 64bit events in the core arm_pmu driver
>> infrastructure and adds the support for armv8 64bit kernel PMU to use
>> chained counters to count in 64bit mode. For CPU cycles, we use the cycle
>> counter in 64bit mode, only when requested. If the cycle counter is not
>> available, we fall back to chaining the counters.
>>
>> Tested on Juno, Fast models. Applies on 4.18-rc4
>
> Thanks, this looks pretty good to me. How far did you get with the perf
> fuzzer?
Hi Will,
I ran perf_fuzzer on Juno and the fuzzer hung with RCU stalls.
However, this was reproducible without the series. I am yet to
investigate the RCU stall.
Log below (from 4.18-rc3, without the series).
[445885.968489] perf_fuzzer R running task 0 11468 4397
0x00000003
[445885.975568] Call trace:
[445885.978084] ret_from_fork+0x0/0x1c
[445963.841606] INFO: rcu_preempt self-detected stall on CPU
[445963.845814] INFO: rcu_preempt detected stalls on CPUs/tasks:
[445963.846957] 2-....: (1 GPs behind) idle=376/1/4611686018427387908
softirq=57145/57145 fqs=54519307
[445963.852649]
[445963.861784] 2-....: (1 GPs behind) idle=376/1/4611686018427387908
softirq=57145/57145 fqs=54519307
[445963.861787] (t=109254007 jiffies g=61092 c=61091 q=1517144)
[445963.878244]
[445963.878245] Task dump for CPU 2:
[445963.878250] perf_fuzzer R
[445963.879897] (detected by 0, t=109254007 jiffies, g=61092, c=61091,
q=1517144)
[445963.883167] running task 0 11468 4397 0x00000003
[445963.898932] Call trace:
[445963.901439] dump_backtrace+0x0/0x1e0
[445963.905149] show_stack+0x24/0x30
[445963.908516] sched_show_task+0x220/0x2c0
[445963.912484] dump_cpu_task+0x48/0x58
[445963.916109] rcu_dump_cpu_stacks+0xa0/0xe0
[445963.920250] rcu_check_callbacks+0xa40/0xc20
[445963.924564] update_process_times+0x34/0x60
[445963.928791] tick_sched_handle.isra.5+0x44/0x68
[445963.933361] tick_sched_timer+0x50/0xa0
[445963.937244] __hrtimer_run_queues+0x19c/0x6d0
[445963.941644] hrtimer_interrupt+0xec/0x248
[445963.945699] arch_timer_handler_phys+0x3c/0x50
[445963.950184] handle_percpu_devid_irq+0xcc/0x4a0
[445963.954754] generic_handle_irq+0x34/0x50
[445963.958808] __handle_domain_irq+0x68/0xc0
[445963.962948] gic_handle_irq+0x60/0xb8
[445963.966657] el1_irq+0xb4/0x130
[445963.969851] __do_softirq+0xcc/0x5c4
[445963.973475] irq_exit+0x12c/0x138
[445963.976841] __handle_domain_irq+0x6c/0xc0
[445963.980981] gic_handle_irq+0x60/0xb8
[445963.984691] el0_irq_naked+0x50/0x5c
[445963.988316] Task dump for CPU 2:
[445963.991601] perf_fuzzer R running task 0 11468 4397
0x00000003
[445963.998679] Call trace:
[445964.001194] ret_from_fork+0x0/0x1c
root@localhost:~# uname -a
Linux localhost.localdomain 4.18.0-rc3 #117 SMP PREEMPT Thu Jul 5
11:47:12 BST 2018 aarch64 aarch64 aarch64 GNU/Linux
Suzuki
prev parent reply other threads:[~2018-07-10 15:01 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-10 8:57 Suzuki K Poulose
2018-07-10 8:57 ` [PATCH v5 1/7] arm_pmu: Clean up maximum period handling Suzuki K Poulose
2018-07-10 8:57 ` [PATCH v5 2/7] arm_pmu: Change API to support 64bit counter values Suzuki K Poulose
2018-07-10 8:58 ` [PATCH v5 3/7] arm_pmu: Add support for 64bit event counters Suzuki K Poulose
2018-07-10 8:58 ` [PATCH v5 4/7] arm_pmu: Tidy up clear_event_idx call backs Suzuki K Poulose
2018-07-10 8:58 ` [PATCH v5 5/7] arm64: perf: Clean up armv8pmu_select_counter Suzuki K Poulose
2018-07-10 8:58 ` [PATCH v5 6/7] arm64: perf: Disable PMU while processing counter overflows Suzuki K Poulose
2018-07-10 8:58 ` [PATCH v5 7/7] arm64: perf: Add support for chaining event counters Suzuki K Poulose
2018-07-10 17:18 ` Mark Rutland
2018-07-10 14:31 ` [PATCH v5 0/7] arm64: perf: Support for chained counters Will Deacon
2018-07-10 15:01 ` Suzuki K Poulose [this message]
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