Hi, I guess I must be missing something. I had understood that if one had multiple block devices being crypted by dm-crypt, if they were being operated on at the same time, their parallel crypto operations would utilize different CPUs. So I just did the following: # lvcreate -L10G -n t1 vg # cryptsetup --verbose --verify-passphrase luksFormat /dev/vg/t1 # cryptsetup luksOpen /dev/vg/t1 t1-use # dd of=/dev/null if=/dev/mapper/t1-use bs=1M count=1000 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 12.1207 s, 86.5 MB/s observe (a series of) "kworker(s)" each using near 100% of a core to carry out the crypto. I say a series of kworkers since it appears to almost be a "relay" of them, each handing the work of to another and going away. But all in all there is only every near 1 full core's worth running. So now... # lvcreate -L10G -n t2 vg # cryptsetup --verbose --verify-passphrase luksFormat /dev/vg/t2 # cryptsetup luksOpen /dev/vg/t2 t2-use # for ((x=1; x<3; x++)); do > dd of=/dev/null if=/dev/mapper/t$x-use bs=1M count=1000 & > done [1] 7369 [2] 7370 # 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 27.62 s, 38.0 MB/s 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 27.8015 s, 37.7 MB/s Here I observe two kworker threads each near 50% of a core. Clearly they are both using the same core. But why? As as an aside, aggregate throughput of the two threads is quite a bit less than a single thread. But what I really want to understand is why crypto kworkers are not being scheduled to different, idle cores. Cheers, b.
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