On Wed, 09 Mar 2011 11:21:53 +0100 Milan Broz <mbroz@xxxxxxxxxx> wrote: Actually, I have been trying to use dmcrypt for my swap (anything that is swapped HAS to be encrypted, of course, because it can be anything). However, while the disk benchmarked gives me the normal 50 MB/s for that disk/partition, reading/writing the swap with encryption only gives me around 1 MB/s. This was so unacceptable that I turned off swap all together: I rather crash when running out of memory than having to wait minutes every moment of the day (and for some reason linux likes to use the swap a lot, even while normally it is not running out of memory). I have an Intel Core 2(tm) cpu (a Quad Core Extreme QX6700), but also x86_64; stock debian kernel. > On 03/09/2011 09:11 AM, Thomas Damgaard wrote: > > I have recently switched from i386 to amd64. After switching to 64 > > bit, I/O on LUKS encrypted devices became horribly slow. > > Do you have any idea what causes this? Or suggestions on how to > > debug this further? > > > > I have submitted a bug report on this on Launchpad. The report > > includes details on performance, hardware, etc. > > Well, seems you already proved the it is Ubuntu kernel only problem. > > So generic suggestions - be sure that > > - you are always using the same encryption parameters (cipher, key > size) (once device is unlocked, performance is kernel only thing, so > this cannot be cryptsetup/LUKS problem) > > - if you are testing fs over dmcrypt, be sure the same fs with the > *same* mount parameters is used. If using barriers switch them off > for test. (barrier=0). Verify with dmesg log. > > - check which kernel cryptoAPI module is used for the encryption > (kernel should load arch sepcific one, e.g. aes_x86_64 vs aes_i586, > not generic one). usually simple lsmod of loaded modules here gives > you hint. Try blacklist that module so generic one is used etc. > > - try some new kernel, I think even Ubuntu provides upstream snapshots > > There is no reason x86_64 should be slower - many people it using, > even on the same hw you have. > > Milan > _______________________________________________ > dm-crypt mailing list > dm-crypt@xxxxxxxx > http://www.saout.de/mailman/listinfo/dm-crypt -- Carlo Wood <carlo@xxxxxxxxxx> _______________________________________________ dm-crypt mailing list dm-crypt@xxxxxxxx http://www.saout.de/mailman/listinfo/dm-crypt
