Package: partman-crypto This isn't really a bug in partman-crypto, but I'm reporting it here for tracking purposes as requested by Steve McIntyre.
The symptom I first experienced was when doing an install on a Tiger Lake laptop with a 1TB SSD. The step where we run blockdev-wipe was going to take over 20 hours. I am currently investigating *why* it's taking so long. The SSD is capable of writing at 1.2GB/s and the CPU is capable of encrypting at >4GB/s, so the measured 13.7MB/s is ridiculous. What I've discovered so far is that writing through the page cache is (part of) the problem: # dd if=/dev/zero bs=64k count=1000 of=/dev/mapper/nvme0n1p4_crypt 4.79s, 13.7MB/s # dd if=/dev/zero bs=64k count=100000 of=/dev/mapper/nvme0n1p4_crypt oflag=direct 13.6s, 481MB/s If you need to get a release out that doesn't crater performance before I find & fix this bug in the kernel, you could change blockdev-wipe.c to use O_DIRECT. That would be a matter of changing the calloc() call on line 86 to posix_memalign() (and an optional memset()) and specifying O_DIRECT on line 161. You need to align to at least 512 bytes, and for safety, I'd align to sysconf(_SC_PAGESIZE). I have not tested this workaround.
