Christoph Hellwig <hch@xxxxxxxxxxxxx> writes: > On Wed, Aug 04, 2010 at 12:25:26PM +0200, Dominik Brodowski wrote: >> Hey, >> >> many thanks for your feedback. It seems the crypto step is the culprit: >> >> Reading 1.1 GB with dd, iflag=direct, bs=8k: >> >> /dev/sd* 35.3 MB/s ( 90 %) >> /dev/md* 39.1 MB/s (100 %) >> /dev/mapper/md*_crypt 3.9 MB/s ( 10 %) >> /dev/mapper/vg1-* 3.9 MB/s ( 10 %) >> >> The "good" news: it also happens on my notebook, even though it has a >> different setup (no raid, disk -> lv/vg -> crypt). On my notebook, I'm >> more than happy to test out different kernel versions, patches etc. >> >> /dev/sd* 17.7 MB/s (100 %) >> /dev/mapper/vg1-* 16.2 MB/s ( 92 %) >> /dev/mapper/*_crypt 3.1 MB/s ( 18 %) > > The good news is that you have it tracked down, the bad news is that > I know very little about dm-crypt. Maybe the issue is the single > threaded decryption in dm-crypt? Can you check how much CPU time > the dm crypt kernel thread uses? I fixed this some time ago with http://linux.derkeiler.com/Mailing-Lists/Kernel/2010-06/msg00181.html The patch is still somewhere in the DeviceMapper meat-grinder, that is usually taking longer. -Andi -- ak@xxxxxxxxxxxxxxx -- Speaking for myself only. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
