On Mon, 29 May 2023, Matthew Wilcox wrote: > On Mon, May 29, 2023 at 04:59:40PM -0400, Mikulas Patocka wrote: > > Hi > > > > I improved the dm-flakey device mapper target, so that it can do random > > corruption of read and write bios - I uploaded it here: > > https://people.redhat.com/~mpatocka/testcases/bcachefs/dm-flakey.c > > > > I set up dm-flakey, so that it corrupts 10% of read bios and 10% of write > > bios with this command: > > dmsetup create flakey --table "0 `blockdev --getsize /dev/ram0` flakey /dev/ram0 0 0 1 4 random_write_corrupt 100000000 random_read_corrupt 100000000" > > I'm not suggesting that any of the bugs you've found are invalid, but 10% > seems really high. Is it reasonable to expect any filesystem to cope > with that level of broken hardware? Can any of our existing ones cope > with that level of flakiness? I mean, I've got some pretty shoddy USB > cables, but ... If you reduce the corruption probability, it will take more iterations to hit the bugs. So, for the "edit-compile-test" loop, the probability should be as high as possible, just to save the developer's time on testing. Mikulas
