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authorDavid Dillow <dillowda@ornl.gov>2011-01-17 02:09:44 +0000
committerRoland Dreier <roland@purestorage.com>2011-03-22 09:39:18 -0700
commit7f9e5c48c1078507747434d4c182ab10925bf98a (patch)
tree7be46b01df63e36cee9f17ec6bf9b0910be321c2 /drivers/net/mlx4
parent1eba843dd7678b9033a0d1ccff21c21b857de77b (diff)
downloadop-kernel-dev-7f9e5c48c1078507747434d4c182ab10925bf98a.zip
op-kernel-dev-7f9e5c48c1078507747434d4c182ab10925bf98a.tar.gz
IB: Increase DMA max_segment_size on Mellanox hardware
By default, each device is assumed to be able only handle 64 KB chunks during DMA. By giving the segment size a larger value, the block layer will coalesce more S/G entries together for SRP, allowing larger requests with the same sg_tablesize setting. The block layer is the only direct user of it, though a few IOMMU drivers reference it as well for their *_map_sg coalescing code. pci-gart_64 on x86, and a smattering on on sparc, powerpc, and ia64. Since other IB protocols could potentially see larger segments with this, let's check those: - iSER is fine, because you limit your maximum request size to 512 KB, so we'll never overrun the page vector in struct iser_page_vec (128 entries currently). It is independent of the DMA segment size, and handles multi-page segments already. - IPoIB is fine, as it maps each page individually, and doesn't use ib_dma_map_sg(). - RDS appears to do the right thing and has no dependencies on DMA segment size, but I don't claim to have done a complete audit. - NFSoRDMA and 9p are OK -- they do not use ib_dma_map_sg(), so they doesn't care about the coalescing. - Lustre's ko2iblnd does not care about coalescing -- it properly walks the returned sg list. This patch ups the value on Mellanox hardware to 1 GB, which matches reported firmware limits on mlx4. Signed-off-by: David Dillow <dillowda@ornl.gov> Signed-off-by: Roland Dreier <roland@purestorage.com>
Diffstat (limited to 'drivers/net/mlx4')
-rw-r--r--drivers/net/mlx4/main.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/net/mlx4/main.c b/drivers/net/mlx4/main.c
index 2765a3c..c835011 100644
--- a/drivers/net/mlx4/main.c
+++ b/drivers/net/mlx4/main.c
@@ -1109,6 +1109,9 @@ static int __mlx4_init_one(struct pci_dev *pdev, const struct pci_device_id *id)
}
}
+ /* Allow large DMA segments, up to the firmware limit of 1 GB */
+ dma_set_max_seg_size(&pdev->dev, 1024 * 1024 * 1024);
+
priv = kzalloc(sizeof *priv, GFP_KERNEL);
if (!priv) {
dev_err(&pdev->dev, "Device struct alloc failed, "
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