From: Robin Murphy <robin.murphy@arm.com>
To: Peter Zijlstra <peterz@infradead.org>,
Mark Rutland <mark.rutland@arm.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>,
Yicong Yang <yangyicong@huawei.com>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Will Deacon <will@kernel.org>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, gregkh@linuxfoundation.org,
yangyicong@hisilicon.com, linuxarm@huawei.com,
Dan Williams <dan.j.williams@intel.com>,
Shaokun Zhang <zhangshaokun@hisilicon.com>,
Jiucheng Xu <jiucheng.xu@amlogic.com>,
Khuong Dinh <khuong@os.amperecomputing.com>,
Robert Richter <rric@kernel.org>,
Atish Patra <atishp@atishpatra.org>,
Anup Patel <anup@brainfault.org>, Andy Gross <agross@kernel.org>,
Bjorn Andersson <andersson@kernel.org>,
Frank Li <Frank.li@nxp.com>,
Shuai Xue <xueshuai@linux.alibaba.com>,
Vineet Gupta <vgupta@kernel.org>, Shawn Guo <shawnguo@kernel.org>,
Fenghua Yu <fenghua.yu@intel.com>,
Dave Jiang <dave.jiang@intel.com>, Wu Hao <hao.wu@intel.com>,
Tom Rix <trix@redhat.com>,
linux-fpga@vger.kernel.org,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Liang Kan <kan.liang@linux.intel.com>
Subject: Re: [PATCH 01/32] perf: Allow a PMU to have a parent
Date: Wed, 7 Jun 2023 12:00:48 +0100 [thread overview]
Message-ID: <d275f8af-a422-dd56-dc7d-931ac22e7f5b@arm.com> (raw)
In-Reply-To: <20230606134816.GF905437@hirez.programming.kicks-ass.net>
On 2023-06-06 14:48, Peter Zijlstra wrote:
> On Tue, Jun 06, 2023 at 02:30:52PM +0100, Mark Rutland wrote:
>
>>>> Uh, *which* CPU device? Do we have a container device for all CPUs?
>>>
>>> drivers/base/cpu.c:per_cpu(cpu_sys_devices, cpu) for whatever the core
>>> pmu is for that cpu ?
>>
>> ... but the struct pmu covers several CPUs, so I don't have a single 'cpu', no?
>>
>> If I have a system where cpu{0,1,2} are Cortex-A53 and cpu{3,4} are Cortex-A57,
>> I have two struct pmu instances, each associated with several CPUs. When I
>> probe each of those I determine a cpumask for each.
>
> Bah :/ Clearly I overlooked the disparity there.
>
>>>>>> My overall favorite is an l2 cache related PMU that is spun up in
>>>>>> arch/arm/kernel/irq.c init_IRQ()
>>>>
>>>> That's an artifact of the L2 cache controller driver getting initialized there;
>>>> ideally we'd have a device for the L2 cache itself (which presumably should
>>>> hang off an aggregate CPU device).
>>>
>>> /sys/devices/system/cpu/cpuN/cache/indexM
>>>
>>> has a struct device somewhere in
>>> drivers/base/cacheinfo.c:ci_index_dev or somesuch.
>>
>> I guess, but I don't think the L2 cache controller (the PL310) is actually tied
>> to that today.
>
> All it would do is make fancy links in sysfs I think, who cares ;-)
>
>>>>> Yeah, we're going to have a ton of them as well. Some of them are PCI
>>>>> devices and have a clear parent, others, not so much :/
>>>>
>>>> In a number of places the only thing we have is the PMU driver, and we don't
>>>> have a driver (or device) for the HW block it's a part of. Largely that's
>>>> interconnect PMUs; we could create container devices there.
>>>
>>> Dont they have a PCI device? But yeah, some are going to be a wee bit
>>> challenging.
>>
>> The system might not even have PCI, so it's arguable that they should just hang
>> off an MMIO bus (which is effectively what the platofrm bus is).
>
> You and your dodgy platforms :-)
For system PMUs we'll pretty much always have a platform device
corresponding to a DT/ACPI entry used to describe MMIO registers and/or
interrupts. In many cases the PMU is going to be the only part of the
underlying device that is meaningful to Linux anyway, so I don't see any
issue with just hanging the PMU device off its corresponding platform
device - it still gives the user a way to map a PMU instance back to
some understandable system topology (i.e. ACPI/DT) to disambiguate, and
that's the most important thing.
Thanks,
Robin.
next prev parent reply other threads:[~2023-06-07 11:05 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-04 13:41 [PATCH 00/32] Add parents to struct pmu -> dev Jonathan Cameron
2023-04-04 13:41 ` [PATCH 01/32] perf: Allow a PMU to have a parent Jonathan Cameron
2023-04-04 13:51 ` Greg KH
2023-04-06 4:03 ` Yicong Yang
2023-04-06 10:16 ` Jonathan Cameron
2023-04-06 12:40 ` Peter Zijlstra
2023-04-06 16:44 ` Jonathan Cameron
2023-04-06 17:08 ` Greg KH
2023-04-12 9:56 ` Jonathan Cameron
2023-04-06 19:49 ` Peter Zijlstra
2023-06-06 13:06 ` Mark Rutland
2023-06-06 13:18 ` Peter Zijlstra
2023-06-06 13:30 ` Mark Rutland
2023-06-06 13:48 ` Peter Zijlstra
2023-06-07 11:00 ` Robin Murphy [this message]
2023-04-12 12:41 ` Robin Murphy
2023-04-04 13:41 ` [PATCH 02/32] perf/hisi-pcie: Assign parent for event_source device Jonathan Cameron
2023-04-04 13:51 ` Greg KH
2023-04-06 3:56 ` Yicong Yang
2023-04-04 13:41 ` [PATCH 03/32] Documentation: hisi-pmu: Drop reference to /sys/devices path Jonathan Cameron
2023-04-04 13:52 ` Greg KH
2023-04-06 3:56 ` Yicong Yang
2023-04-04 13:41 ` [PATCH 04/32] perf/hisi-uncore: Assign parents for event_source devices Jonathan Cameron
2023-04-04 13:52 ` Greg KH
2023-04-06 3:57 ` Yicong Yang
2023-04-04 13:41 ` [PATCH 05/32] Documentation: hns-pmu: Use /sys/bus/event_source/devices paths Jonathan Cameron
2023-04-04 13:52 ` Greg KH
2023-04-04 13:41 ` [PATCH 06/32] perf/hisi-hns3: Assign parents for event_source device Jonathan Cameron
2023-04-04 13:42 ` [PATCH 07/32] perf/amlogic: Assign parents for event_source devices Jonathan Cameron
2023-04-10 2:00 ` Jiucheng Xu
2023-04-04 13:42 ` [PATCH 08/32] perf/arm_cspmu: " Jonathan Cameron
2023-04-04 14:50 ` Suzuki K Poulose
2023-04-04 13:42 ` [PATCH 09/32] Documentation: xgene-pmu: Use /sys/bus/event_source/devices paths Jonathan Cameron
2023-04-04 13:42 ` [PATCH 10/32] perf/xgene: Assign parents for event_source devices Jonathan Cameron
2023-04-04 13:42 ` [PATCH 11/32] Documentation: thunderx2-pmu: Use /sys/bus/event_source/devices paths Jonathan Cameron
2023-04-04 13:42 ` [PATCH 12/32] perf/thunderx2: Assign parents for event_source devices Jonathan Cameron
2023-04-04 13:42 ` [PATCH 13/32] perf/riscv: " Jonathan Cameron
2023-04-04 13:42 ` [PATCH 14/32] Documentation: qcom-pmu: Use /sys/bus/event_source/devices paths Jonathan Cameron
2023-04-04 13:42 ` [PATCH 15/32] perf/qcom: Assign parents for event_source devices Jonathan Cameron
2023-04-04 13:42 ` [PATCH 16/32] perf/imx_ddr: " Jonathan Cameron
2023-04-04 13:42 ` [PATCH 17/32] perf/arm_pmu: " Jonathan Cameron
2023-04-04 13:42 ` [PATCH 18/32] perf/alibaba_uncore: Assign parents for event_source device Jonathan Cameron
2023-04-05 3:50 ` Shuai Xue
2023-04-04 13:42 ` [PATCH 19/32] perf/arm-cci: " Jonathan Cameron
2023-04-04 14:45 ` Suzuki K Poulose
2023-04-04 13:42 ` [PATCH 20/32] perf/arm-ccn: " Jonathan Cameron
2023-04-12 12:09 ` Suzuki K Poulose
2023-04-04 13:42 ` [PATCH 21/32] perf/arm-cmn: " Jonathan Cameron
2023-04-12 11:52 ` Robin Murphy
2023-04-04 13:42 ` [PATCH 22/32] perf/arm-dmc620: " Jonathan Cameron
2023-04-04 13:42 ` [PATCH 23/32] perf/arm-dsu: " Jonathan Cameron
2023-04-04 14:52 ` Suzuki K Poulose
2023-04-04 13:42 ` [PATCH 24/32] perf/arm-smmuv3: " Jonathan Cameron
2023-04-04 13:42 ` [PATCH 25/32] perf/arm-spe: " Jonathan Cameron
2023-04-12 12:08 ` Suzuki K Poulose
2023-04-04 13:42 ` [PATCH 26/32] arc: Assign parents for event_source devices Jonathan Cameron
2023-04-04 13:42 ` [PATCH 27/32] ARM: imx: Assign parents for mmdc " Jonathan Cameron
2023-04-04 13:42 ` [PATCH 28/32] dmaengine: idxd: Assign parent for event_source device Jonathan Cameron
2023-04-04 13:42 ` [PATCH 29/32] fpga: dfl: " Jonathan Cameron
2023-04-07 6:42 ` Xu Yilun
2023-04-04 13:42 ` [PATCH 30/32] drivers/nvdimm: " Jonathan Cameron
2023-04-05 5:05 ` Dan Williams
2023-04-04 13:42 ` [PATCH 31/32] Documentation: ABI + trace: hisi_ptt: update paths to bus/event_source Jonathan Cameron
2023-04-06 3:54 ` Yicong Yang
2023-04-04 13:42 ` [PATCH 32/32] hwtracing: hisi_ptt: Assign parent for event_source device Jonathan Cameron
2023-04-06 3:55 ` Yicong Yang
2023-04-04 13:51 ` [PATCH 00/32] Add parents to struct pmu -> dev Greg KH
2023-04-04 14:40 ` Greg KH
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