Message-ID: <489CA21F.1030604@s5r6.in-berlin.de>
Date: Fri, 08 Aug 2008 21:44:31 +0200
From: Stefan Richter <stefanr@s5r6.in-berlin.de>
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Subject: Scatter-gather segment merges by IOMMU?
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Hi all,

the block layer usually tries to merge s/g segments if consecutive 
segments combined fit into the queue's max_segment_size.  When such a 
scatter gather list is DMA-mapped, can it happen that an IOMMU collapses 
the elements even further, so that sg_dma_len() of a DMA-mapped s/g 
segment exceeds max_segment_size?

As I understood some discussions in the past, this could indeed happen, 
which is a nuisance.  But I may have misunderstood something, or 
something may have changed in the meantime...
-- 
Stefan Richter
-=====-==--- =--- -=---
http://arcgraph.de/sr/
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