From: Christoph Hellwig <hch@lst.de>
To: John Garry <john.garry@huawei.com>
Cc: 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, iommu@lists.linux-foundation.org,
linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
linuxarm@huawei.com
Subject: Re: [PATCH 0/6] dma mapping/iommu: Allow IOMMU IOVA rcache range to be configured
Date: Fri, 19 Mar 2021 14:40:47 +0100 [thread overview]
Message-ID: <20210319134047.GA5729@lst.de> (raw)
In-Reply-To: <1616160348-29451-1-git-send-email-john.garry@huawei.com>
On Fri, Mar 19, 2021 at 09:25:42PM +0800, John Garry wrote:
> For streaming DMA mappings involving an IOMMU and whose IOVA len regularly
> exceeds the IOVA rcache upper limit (meaning that they are not cached),
> performance can be reduced.
>
> This is much more pronounced from commit 4e89dce72521 ("iommu/iova: Retry
> from last rb tree node if iova search fails"), as discussed at [0].
>
> IOVAs which cannot be cached are highly involved in the IOVA aging issue,
> as discussed at [1].
I'm confused. If this a limit in the IOVA allocator, dma-iommu should
be able to just not grow the allocation so larger without help from
the driver.
If contrary to the above description it is device-specific, the driver
could simply use dma_get_max_seg_size().
next prev parent reply other threads:[~2021-03-19 13:41 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-19 13:25 [PATCH 0/6] dma mapping/iommu: Allow IOMMU IOVA rcache range to be configured John Garry
2021-03-19 13:25 ` [PATCH 1/6] iommu: Move IOVA power-of-2 roundup into allocator John Garry
2021-03-19 16:13 ` Robin Murphy
2021-03-19 16:58 ` John Garry
2021-03-19 19:20 ` Robin Murphy
2021-03-22 15:01 ` John Garry
2021-03-31 9:58 ` Robin Murphy
2021-04-06 16:54 ` John Garry
2021-04-14 17:44 ` John Garry
2021-03-19 13:25 ` [PATCH 2/6] iova: Add a per-domain count of reserved nodes John Garry
2021-03-19 13:25 ` [PATCH 3/6] iova: Allow rcache range upper limit to be configurable John Garry
2021-03-19 16:25 ` Robin Murphy
2021-03-19 17:26 ` John Garry
2021-03-31 10:53 ` Robin Murphy
2021-03-19 13:25 ` [PATCH 4/6] iommu: Add iommu_dma_set_opt_size() John Garry
2021-03-19 13:25 ` [PATCH 5/6] dma-mapping/iommu: Add dma_set_max_opt_size() John Garry
2021-03-19 17:00 ` Robin Murphy
2021-03-19 18:02 ` John Garry
2021-03-31 8:01 ` Salil Mehta
2021-03-31 8:08 ` Salil Mehta
2021-03-19 13:25 ` [PATCH 6/6] scsi: hisi_sas: Set max optimal DMA size for v3 hw John Garry
2021-03-19 13:40 ` Christoph Hellwig [this message]
2021-03-19 15:42 ` [PATCH 0/6] dma mapping/iommu: Allow IOMMU IOVA rcache range to be configured John Garry
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