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From: John Garry via iommu <iommu@lists.linux-foundation.org>
To: <damien.lemoal@opensource.wdc.com>, <joro@8bytes.org>,
	<will@kernel.org>,  <jejb@linux.ibm.com>,
	<martin.petersen@oracle.com>, <hch@lst.de>,
	<m.szyprowski@samsung.com>, <robin.murphy@arm.com>
Cc: linux-scsi@vger.kernel.org, linux-doc@vger.kernel.org,
	linuxarm@huawei.com, iommu@lists.linux.dev,
	linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org,
	iommu@lists.linux-foundation.org
Subject: Re: [PATCH v5 0/5] DMA mapping changes for SCSI core
Date: Wed, 6 Jul 2022 14:40:44 +0100	[thread overview]
Message-ID: <b5f80062-e8ef-9597-1b0c-393140950dfb@huawei.com> (raw)
In-Reply-To: <1656590892-42307-1-git-send-email-john.garry@huawei.com>

On 30/06/2022 13:08, John Garry wrote:

Hi Christoph,

Can you please consider picking up this series? A few things to note 
beforehand:

- I changed to only apply the mapping limit to SAS hosts in this 
version. I would need a fresh ack from Martin for those SCSI parts, but 
wanted to make sure you were ok with it.
- Damien had some doubt on updating the shost max_sectors as opposed to 
the per-request queue default, but I think he's ok with it - see patch 4/5

Thanks,
John


> As reported in [0], DMA mappings whose size exceeds the IOMMU IOVA caching
> limit may see a big performance hit.
> 
> This series introduces a new DMA mapping API, dma_opt_mapping_size(), so
> that drivers may know this limit when performance is a factor in the
> mapping.
> 
> The SCSI SAS transport code is modified only to use this limit. For now I
> did not want to touch other hosts as I have a concern that this change
> could cause a performance regression.
> 
> I also added a patch for libata-scsi as it does not currently honour the
> shost max_sectors limit.
> 
> [0]https://lore.kernel.org/linux-iommu/20210129092120.1482-1-thunder.leizhen@huawei.com/
> 
> Changes since v4:
> - tweak libata and other patch titles
> - Add Robin's tag (thanks!)
> - Clarify description of new DMA mapping API

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WARNING: multiple messages have this Message-ID (diff)
From: John Garry <john.garry@huawei.com>
To: <damien.lemoal@opensource.wdc.com>, <joro@8bytes.org>,
	<will@kernel.org>, <jejb@linux.ibm.com>,
	<martin.petersen@oracle.com>, <hch@lst.de>,
	<m.szyprowski@samsung.com>, <robin.murphy@arm.com>
Cc: <linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-ide@vger.kernel.org>, <iommu@lists.linux-foundation.org>,
	<iommu@lists.linux.dev>, <linux-scsi@vger.kernel.org>,
	<linuxarm@huawei.com>
Subject: Re: [PATCH v5 0/5] DMA mapping changes for SCSI core
Date: Wed, 6 Jul 2022 14:40:44 +0100	[thread overview]
Message-ID: <b5f80062-e8ef-9597-1b0c-393140950dfb@huawei.com> (raw)
Message-ID: <20220706134044.Ajmp8yJtUBejg6eWWyBnhSFcKd15VjBQKdTyQnZupcE@z> (raw)
In-Reply-To: <1656590892-42307-1-git-send-email-john.garry@huawei.com>

On 30/06/2022 13:08, John Garry wrote:

Hi Christoph,

Can you please consider picking up this series? A few things to note 
beforehand:

- I changed to only apply the mapping limit to SAS hosts in this 
version. I would need a fresh ack from Martin for those SCSI parts, but 
wanted to make sure you were ok with it.
- Damien had some doubt on updating the shost max_sectors as opposed to 
the per-request queue default, but I think he's ok with it - see patch 4/5

Thanks,
John


> As reported in [0], DMA mappings whose size exceeds the IOMMU IOVA caching
> limit may see a big performance hit.
> 
> This series introduces a new DMA mapping API, dma_opt_mapping_size(), so
> that drivers may know this limit when performance is a factor in the
> mapping.
> 
> The SCSI SAS transport code is modified only to use this limit. For now I
> did not want to touch other hosts as I have a concern that this change
> could cause a performance regression.
> 
> I also added a patch for libata-scsi as it does not currently honour the
> shost max_sectors limit.
> 
> [0]https://lore.kernel.org/linux-iommu/20210129092120.1482-1-thunder.leizhen@huawei.com/
> 
> Changes since v4:
> - tweak libata and other patch titles
> - Add Robin's tag (thanks!)
> - Clarify description of new DMA mapping API


  parent reply	other threads:[~2022-07-06 13:40 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-30 12:08 [PATCH v5 0/5] DMA mapping changes for SCSI core John Garry via iommu
2022-06-30 12:08 ` John Garry
2022-06-30 12:08 ` [PATCH v5 1/5] dma-mapping: Add dma_opt_mapping_size() John Garry via iommu
2022-06-30 12:08   ` John Garry
2022-06-30 12:08 ` [PATCH v5 2/5] dma-iommu: Add iommu_dma_opt_mapping_size() John Garry via iommu
2022-06-30 12:08   ` John Garry
2022-06-30 12:08 ` [PATCH v5 3/5] scsi: core: Cap shost max_sectors according to DMA limits only once John Garry via iommu
2022-06-30 12:08   ` John Garry
2022-06-30 23:41   ` Damien Le Moal via iommu
2022-06-30 23:41     ` Damien Le Moal
2022-07-01  8:02     ` John Garry via iommu
2022-07-01  8:02       ` John Garry
2022-06-30 12:08 ` [PATCH v5 4/5] scsi: scsi_transport_sas: Cap shost max_sectors according to DMA optimal limit John Garry via iommu
2022-06-30 12:08   ` John Garry
2022-06-30 23:49   ` Damien Le Moal via iommu
2022-06-30 23:49     ` Damien Le Moal
2022-07-01  8:46     ` John Garry via iommu
2022-07-01  8:46       ` John Garry
2022-06-30 12:08 ` [PATCH v5 5/5] ata: libata-scsi: Cap ata_device->max_sectors according to shost->max_sectors John Garry via iommu
2022-06-30 12:08   ` John Garry
2022-07-06 13:40 ` John Garry via iommu [this message]
2022-07-06 13:40   ` [PATCH v5 0/5] DMA mapping changes for SCSI core John Garry
2022-07-06 13:44   ` Christoph Hellwig
2022-07-06 13:44     ` Christoph Hellwig
2022-07-07 20:35     ` Martin K. Petersen
2022-07-08 16:17       ` John Garry
2022-07-10 23:08         ` Damien Le Moal
2022-07-11  7:36           ` John Garry
2022-07-11 10:40             ` Damien Le Moal
2022-07-11 14:49               ` John Garry
2022-07-14  3:10         ` Martin K. Petersen
2022-07-14  7:52           ` John Garry

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