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From: Xu Zaibo <xuzaibo@huawei.com>
To: Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: <iommu@lists.linux-foundation.org>, <devicetree@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-pci@vger.kernel.org>, <linux-mm@kvack.org>,
	<mark.rutland@arm.com>, <kevin.tian@intel.com>,
	Jean-Philippe Brucker <jean-philippe.brucker@arm.com>,
	<catalin.marinas@arm.com>, <robin.murphy@arm.com>,
	<robh+dt@kernel.org>, <zhangfei.gao@linaro.org>,
	<will@kernel.org>, <christian.koenig@amd.com>, <tj@kernel.org>
Subject: Re: [PATCH v4 03/26] iommu: Add a page fault handler
Date: Wed, 26 Feb 2020 11:05:19 +0800	[thread overview]
Message-ID: <0c2b29ad-d09a-89db-8540-5909751b1972@huawei.com> (raw)
In-Reply-To: <20200225092519.GC375953@myrica>

Hi,
On 2020/2/25 17:25, Jean-Philippe Brucker wrote:
> Hi Zaibo,
>
> On Tue, Feb 25, 2020 at 11:30:05AM +0800, Xu Zaibo wrote:
>>> +struct iopf_queue *
>>> +iopf_queue_alloc(const char *name, iopf_queue_flush_t flush, void *cookie)
>>> +{
>>> +	struct iopf_queue *queue;
>>> +
>>> +	queue = kzalloc(sizeof(*queue), GFP_KERNEL);
>>> +	if (!queue)
>>> +		return NULL;
>>> +
>>> +	/*
>>> +	 * The WQ is unordered because the low-level handler enqueues faults by
>>> +	 * group. PRI requests within a group have to be ordered, but once
>>> +	 * that's dealt with, the high-level function can handle groups out of
>>> +	 * order.
>>> +	 */
>>> +	queue->wq = alloc_workqueue("iopf_queue/%s", WQ_UNBOUND, 0, name);
>> Should this workqueue use 'WQ_HIGHPRI | WQ_UNBOUND' or some flags like this
>> to decrease the unexpected
>> latency of I/O PageFault here? Or maybe, workqueue will show an uncontrolled
>> latency, even in a busy system.
> I'll investigate the effect of these flags. So far I've only run on
> completely idle systems but it would be interesting to add some
> workqueue-heavy load in my tests.
>
I'm not sure, just my concern. Hopefully, Tejun Heo can give us some 
hints. :)

+cc  Tejun Heo <tj@kernel.org>

Cheers,
Zaibo

.
> .
>



  reply	other threads:[~2020-02-26  3:05 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-24 18:23 [PATCH v4 00/26] iommu: Shared Virtual Addressing and SMMUv3 support Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 01/26] mm/mmu_notifiers: pass private data down to alloc_notifier() Jean-Philippe Brucker
2020-02-24 19:00   ` Jason Gunthorpe
2020-02-25  9:24     ` Jean-Philippe Brucker
2020-02-25 14:08       ` Jason Gunthorpe
2020-02-28 14:39         ` Jean-Philippe Brucker
2020-02-28 14:48           ` Jason Gunthorpe
2020-02-28 15:04             ` Jean-Philippe Brucker
2020-02-28 15:13               ` Jason Gunthorpe
2020-03-06  9:56                 ` Jean-Philippe Brucker
2020-03-06 13:09                   ` Jason Gunthorpe
2020-03-06 14:35                     ` Jean-Philippe Brucker
2020-03-06 14:52                       ` Jason Gunthorpe
2020-03-06 16:15                         ` Jean-Philippe Brucker
2020-03-06 17:42                           ` Jason Gunthorpe
2020-03-13 18:49                             ` Jean-Philippe Brucker
2020-03-13 19:13                               ` Jason Gunthorpe
2020-03-16 15:46                     ` Christoph Hellwig
2020-03-17 18:40                       ` Jason Gunthorpe
2020-03-05 16:36   ` Christoph Hellwig
2020-02-24 18:23 ` [PATCH v4 02/26] iommu/sva: Manage process address spaces Jean-Philippe Brucker
2020-02-26 12:35   ` Jonathan Cameron
2020-02-28 14:43     ` Jean-Philippe Brucker
2020-02-28 16:26       ` Jonathan Cameron
2020-02-26 19:13   ` Jacob Pan
2020-02-28 14:40     ` Jean-Philippe Brucker
2020-02-28 14:57       ` Jason Gunthorpe
2020-02-24 18:23 ` [PATCH v4 03/26] iommu: Add a page fault handler Jean-Philippe Brucker
2020-02-25  3:30   ` Xu Zaibo
2020-02-25  9:25     ` Jean-Philippe Brucker
2020-02-26  3:05       ` Xu Zaibo [this message]
2020-02-26 13:59   ` Jonathan Cameron
2020-02-28 14:44     ` Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 04/26] iommu/sva: Search mm by PASID Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 05/26] iommu/iopf: Handle mm faults Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 06/26] iommu/sva: Register page fault handler Jean-Philippe Brucker
2020-02-26 19:39   ` Jacob Pan
2020-02-28 14:44     ` Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 07/26] arm64: mm: Pin down ASIDs for sharing mm with devices Jean-Philippe Brucker
2020-02-27 17:43   ` Jonathan Cameron
2020-03-04 14:10     ` Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 08/26] iommu/io-pgtable-arm: Move some definitions to a header Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 09/26] iommu/arm-smmu-v3: Manage ASIDs with xarray Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 10/26] arm64: cpufeature: Export symbol read_sanitised_ftr_reg() Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 11/26] iommu/arm-smmu-v3: Share process page tables Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 12/26] iommu/arm-smmu-v3: Seize private ASID Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 13/26] iommu/arm-smmu-v3: Add support for VHE Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 14/26] iommu/arm-smmu-v3: Enable broadcast TLB maintenance Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 15/26] iommu/arm-smmu-v3: Add SVA feature checking Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 16/26] iommu/arm-smmu-v3: Add dev_to_master() helper Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 17/26] iommu/arm-smmu-v3: Implement mm operations Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 18/26] iommu/arm-smmu-v3: Hook up ATC invalidation to mm ops Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 19/26] iommu/arm-smmu-v3: Add support for Hardware Translation Table Update Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 20/26] iommu/arm-smmu-v3: Maintain a SID->device structure Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 21/26] iommu/arm-smmu-v3: Ratelimit event dump Jean-Philippe Brucker
2021-05-28  8:09   ` Aaro Koskinen
2021-05-28 16:25     ` Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 22/26] dt-bindings: document stall property for IOMMU masters Jean-Philippe Brucker
2020-02-24 18:23 ` [PATCH v4 23/26] iommu/arm-smmu-v3: Add stall support for platform devices Jean-Philippe Brucker
2020-02-26  8:44   ` Xu Zaibo
2020-03-04 14:09     ` Jean-Philippe Brucker
2020-02-27 18:17   ` Jonathan Cameron
2020-03-04 14:08     ` Jean-Philippe Brucker
2020-03-09 10:48       ` Jonathan Cameron
2020-02-24 18:23 ` [PATCH v4 24/26] PCI/ATS: Add PRI stubs Jean-Philippe Brucker
2020-02-27 20:55   ` Bjorn Helgaas
2020-02-24 18:24 ` [PATCH v4 25/26] PCI/ATS: Export symbols of PRI functions Jean-Philippe Brucker
2020-02-27 20:55   ` Bjorn Helgaas
2020-02-24 18:24 ` [PATCH v4 26/26] iommu/arm-smmu-v3: Add support for PRI Jean-Philippe Brucker
2020-02-27 18:22 ` [PATCH v4 00/26] iommu: Shared Virtual Addressing and SMMUv3 support Jonathan Cameron

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