I have about 45% CPU on a very low end AMD Sempron(tm) Processor LE-1250 for 30MB/s. You probably should have bought faster cores instead of more. Incidentially, I believe your request has about zero prospect of being sucessful. It is a lot of effort for basically very few people having any gain. I would not do it unless fully paid, but thet _wpuld_ be expensive. Arno On Wed, Sep 17, 2008 at 03:41:40AM +0300, Sami Liedes wrote: > On Wed, Sep 17, 2008 at 01:44:16AM +0200, Arno Wagner wrote: > > hat do you want multicore support for ayways? Do you have an > > application that can actually saturate even one core? Multicore > > sounds like basicelly costing a lot of effort and postential > > problems for nothing in return. > > Yes, easily. I find quite often that kcryptd takes 100% of one CPU, > including in non-artificial setups when working with huge files. > Perhaps it's the 3 disk raid capable of 200 MiB/s, I don't know, > that's just what I've seen watching top. Of course might be that > dm-crypt is broken in some other way that makes it sometimes take lots > of CPU. The effect would probably be more noticeable on some older SMP > hardware; I have a Core 2 Quad. > > As an artificial benchmark that should probably give an upper bound on > the speedup in my case: > > ------------------------------------------------------------ > # hdparm -t /dev/mapper/myvg-root > > /dev/mapper/myvg-root: > Timing buffered disk reads: 634 MB in 3.01 seconds = 210.90 MB/sec > # hdparm -t /dev/mapper/myvg-root_crypt > > /dev/mapper/myvg-root_crypt: > Timing buffered disk reads: 258 MB in 3.01 seconds = 85.79 MB/sec > ------------------------------------------------------------ > > I don't know about the internals, but I'd assume multiple threads > could also reduce read latency by breaking up large requests. > Definitely dm-crypt noticeably slows down disk access, so I guess the > question is how much of the performance could be gained back by > multiple threads. > > At the moment my computer has been up for 22 days and ps shows kcryptd > has so far taken 14.5 hours of CPU time, and I'm sure it's not evenly > distributed over the uptime; this is not a database server or a high > load web server or anything like that. > > Hm, you said there's currently one thread per device. So would it > theoretically help if I ran raid (or lvm) over dm-crypt, not the other > way round? Perhaps I should try that, although it somehow seems > backwards. > > Sami > > --------------------------------------------------------------------- > dm-crypt mailing list - http://www.saout.de/misc/dm-crypt/ > To unsubscribe, e-mail: dm-crypt-unsubscribe@xxxxxxxx > For additional commands, e-mail: dm-crypt-help@xxxxxxxx > -- Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno@xxxxxxxxxxx GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F ---- Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans If it's in the news, don't worry about it. The very definition of "news" is "something that hardly ever happens." -- Bruce Schneier --------------------------------------------------------------------- dm-crypt mailing list - http://www.saout.de/misc/dm-crypt/ To unsubscribe, e-mail: dm-crypt-unsubscribe@xxxxxxxx For additional commands, e-mail: dm-crypt-help@xxxxxxxx
