On Tue, Feb 09, 2010 at 01:28:06AM +0100, Arno Wagner wrote: > On Tue, Feb 09, 2010 at 12:54:16AM +0100, Jakob Sandgren wrote: > > Hi, > > > > (please keep me on CC since I'm not subscribed yet) > > > > To me it seems like there is some serious flaw within kcryptd that > > ends up to wait for "something" instead of sending enough requests to > > the disks to make sure it has data to decrypt. What do you think? > > The same thing. > > Here is a reference test (I have notebook disks in this server): > > Raw read: 54MB/s 14% CPU > Read with decrypt: 53MB/s 65% CPU For reference this is the exact output of my benchmark, maybe there are some difference in setup or benchmark? OOOOOooops! While putting toghether this information I actually found the cause of the problem, it was my benchark that was wrong! This was the benchmark I used to get the performance was: dd if=/dev/mapper/bench1 bs=4M iflag=direct |pv | dd of=/dev/null and the number reported by "pv" during the run was ~75MB/s and dd reported the same number when finished. Changing this to: dd if=/dev/mapper/bench1 bs=4M iflag=direct of=/dev/null count=1000 gave a more correct number; 125MB/s I was not aware of that piping the data through pv would cause such a big degradation in performance. > That would mean the crypto is pretty slow on your new CPU. > As a reference, my 53MB/s at 65% CPU is on an 2800MHz Athlon > 64 X2 5600+ with aes-cbc-plain. > > Here is an OpenSSL crypto speed test: > openssl speed -evp aes-256-cbc > [...] > The 'numbers' are in 1000s of bytes per second processed. > type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes > aes-256-cbc 71848.00k 98649.49k 110187.78k 113646.25k 114666.15k > > You might want to compare this with the numbers on your CPU. The numbers from my system (Core I7) are below root@mvh:~# openssl speed -evp aes-256-cbc ... The 'numbers' are in 1000s of bytes per second processed. type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes aes-256-cbc 110769.28k 118629.67k 120600.15k 121138.86k 121206.10k I has now been able to get a 175MB/sec from my main raid partition. Best Regards, Jakob -- _______________________________________________ dm-crypt mailing list dm-crypt@xxxxxxxx http://www.saout.de/mailman/listinfo/dm-crypt
