From: Lu Baolu <baolu.lu@linux.intel.com>
To: "Tian, Kevin" <kevin.tian@intel.com>,
"Pan, Jacob jun" <jacob.jun.pan@intel.com>,
"Raj, Ashok" <ashok.raj@intel.com>,
"Liu, Yi L" <yi.l.liu@intel.com>
Cc: baolu.lu@linux.intel.com,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/3] iommu/vt-d: Size Page Request Queue to avoid overflow condition
Date: Mon, 18 Apr 2022 19:44:44 +0800 [thread overview]
Message-ID: <46f51f30-28e9-4b91-acd5-1df43c1428d6@linux.intel.com> (raw)
In-Reply-To: <BN9PR11MB5276BC4D5F9B133C84630CBA8CF39@BN9PR11MB5276.namprd11.prod.outlook.com>
On 2022/4/18 15:00, Tian, Kevin wrote:
>> From: Lu Baolu<baolu.lu@linux.intel.com>
>> Sent: Saturday, April 16, 2022 8:31 PM
>>
>> PRQ overflow may cause I/O throughput congestion, resulting in unnecessary
>> degradation of IO performance. Appropriately increasing the length of PRQ
>> can greatly reduce the occurrence of PRQ overflow. The count of maximum
>> page requests that can be generated in parallel by a PCIe device is
>> statically defined in the Outstanding Page Request Capacity field of the
>> PCIe ATS configure space.
>>
>> The new lenght of PRQ is calculated by summing up the value of Outstanding
>> Page Request Capacity register across all devices where Page Requests are
>> supported on the real PR-capable platfrom (Intel Sapphire Rapids). The
>> result is round to the nearest higher power of 2.
> The actual requirement is usage and platform specific. What about
> doubling the default size and also provide an option for admin to
> tune?
I also have this in my list to provide an opt-in interface for user. But
I don't want to include it in this series as this is only for small
tuning. The opt-in interface looks more like a new feature. :-)
Best regards,
baolu
prev parent reply other threads:[~2022-04-18 11:44 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-16 12:30 [PATCH 0/3] iommu/vt-d: Some fine tuning of SVA Lu Baolu
2022-04-16 12:30 ` [PATCH 1/3] iommu/vt-d: Set PGSNP bit in pasid table entry for sva binding Lu Baolu
2022-04-18 6:56 ` Tian, Kevin
2022-04-18 11:28 ` Lu Baolu
2022-04-16 12:30 ` [PATCH 2/3] iommu/vt-d: Drop stop marker messages Lu Baolu
2022-04-18 6:58 ` Tian, Kevin
2022-04-18 11:37 ` Lu Baolu
2022-04-16 12:30 ` [PATCH 3/3] iommu/vt-d: Size Page Request Queue to avoid overflow condition Lu Baolu
2022-04-18 7:00 ` Tian, Kevin
2022-04-18 11:44 ` Lu Baolu [this message]
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