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Subject: Re: [PATCH] drivers/perf: hisi: Schedule perf session according to
 locality
To:     Will Deacon <will@kernel.org>
CC:     <jonathan.cameron@huawei.com>, <mark.rutland@arm.com>,
        <hejunhao3@huawei.com>, <prime.zeng@hisilicon.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <yangyicong@hisilicon.com>
References: <20230808125147.2080-1-yangyicong@huawei.com>
 <20230811111414.GC6993@willie-the-truck>
From:   Yicong Yang <yangyicong@huawei.com>
Message-ID: <8b3ea6aa-2751-9612-4b91-82640e8dde0f@huawei.com>
Date:   Tue, 15 Aug 2023 19:02:45 +0800
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On 2023/8/11 19:14, Will Deacon wrote:
> On Tue, Aug 08, 2023 at 08:51:47PM +0800, Yicong Yang wrote:
>> From: Yicong Yang <yangyicong@hisilicon.com>
>>
>> The PCIe PMUs locate on different NUMA node but currently we don't
>> consider it and likely stack all the sessions on the same CPU:
>>
>> [root@localhost tmp]# cat /sys/devices/hisi_pcie*/cpumask
>> 0
>> 0
>> 0
>> 0
>> 0
>> 0
>>
>> This can be optimize a bit to use a local CPU for the PMU.
>>
>> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
>> ---
>>  drivers/perf/hisilicon/hisi_pcie_pmu.c | 15 ++++++++++++---
>>  1 file changed, 12 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/perf/hisilicon/hisi_pcie_pmu.c b/drivers/perf/hisilicon/hisi_pcie_pmu.c
>> index e10fc7cb9493..60ecf469782b 100644
>> --- a/drivers/perf/hisilicon/hisi_pcie_pmu.c
>> +++ b/drivers/perf/hisilicon/hisi_pcie_pmu.c
>> @@ -665,7 +665,7 @@ static int hisi_pcie_pmu_online_cpu(unsigned int cpu, struct hlist_node *node)
>>  	struct hisi_pcie_pmu *pcie_pmu = hlist_entry_safe(node, struct hisi_pcie_pmu, node);
>>  
>>  	if (pcie_pmu->on_cpu == -1) {
>> -		pcie_pmu->on_cpu = cpu;
>> +		pcie_pmu->on_cpu = cpumask_local_spread(0, dev_to_node(&pcie_pmu->pdev->dev));
>>  		WARN_ON(irq_set_affinity(pcie_pmu->irq, cpumask_of(cpu)));
> 
> Hmm, this is a bit weird now, because the interrupt is affine to a different
> CPU from the one you've chosen. Are you sure that's ok? When the offline
> notifier picks a new target, it moves the irq as well.
> 

Thanks for pointing it out. This is indeed a problem. Will fix this.

Thanks.