From: Stefan Richter <stefanr@s5r6.in-berlin.de>
To: linux-scsi@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Subject: Scatter-gather segment merges by IOMMU?
Date: Fri, 08 Aug 2008 21:44:31 +0200 [thread overview]
Message-ID: <489CA21F.1030604@s5r6.in-berlin.de> (raw)
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/
next reply other threads:[~2008-08-08 19:44 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-08 19:44 Stefan Richter [this message]
2008-08-08 20:25 ` Grant Grundler
2008-08-08 21:21 ` Stefan Richter
2008-08-08 21:31 ` FUJITA Tomonori
2008-08-08 21:58 ` Stefan Richter
2008-08-08 22:17 ` FUJITA Tomonori
2008-08-09 18:20 ` [PATCH] ieee1394: sbp2: enforce s/g segment size limit Stefan Richter
2008-08-09 18:21 ` [PATCH] firewire: fw-sbp2: " Stefan Richter
2008-08-11 19:52 ` Grant Grundler
2008-08-13 9:38 ` Stefan Richter
2008-08-12 17:04 ` [PATCH] ieee1394: sbp2: " Grant Grundler
2008-08-12 23:44 ` FUJITA Tomonori
2008-08-13 10:19 ` [PATCH update] " Stefan Richter
2008-08-13 10:20 ` [PATCH update] firewire: fw-sbp2: " Stefan Richter
2008-08-13 10:27 ` [PATCH update] ieee1394: sbp2: " Stefan Richter
2008-08-14 0:55 ` FUJITA Tomonori
2008-08-14 7:12 ` Stefan Richter
2008-08-14 7:21 ` FUJITA Tomonori
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