On 2018/7/7 11:55 AM, Cameron Berkenpas wrote: > Hello, > > I've recently tried to play around with bcache on some PPC64LE (POWER9, > little endian mode) hardware, and I've run into some issues. > > I can format a device as a backing store no problem. If I never attach a > caching device, it never has problems. > > I can format a caching device no problem, I can attach it without issue > and use the cached bcache volume without issue. > > If I detach the caching device, no perceivable issues. However, once I > attempted to re-attach the caching device, bcache hangs. For example, if > I try to cat an arbitrary item under /sys, (such as 'cat > /sys/block/bcache0/bcache/sequential_cutoff'), it will hang indefinitely. > > If I reboot with the caching device attached, then after the system > comes back up, neither the caching and the backing volumes will be > recognized as bcache devices and are unmountable, and both must have > make-bcache run on them. > > If I never attach a caching device to the backing device, the backing > never has problems. It appears to stay healthy between reboots. I've had > uptimes of over 8 hours without a caching device without issue. No sort > of load was put on the volume, but otherwise, no issues. > > The RAID controller I'm using (details below) is a very thoroughly > tested device that reports no issues. Specifically, the RAID controller > was tested on an x86 machine that's using bcache in the same manner as > here without issue. > > What is the appropriate place to file a bug against this issue? > > I've tried against multiple filesystems: > xfs > ext4 > btrfs > > I've tried against multiple kernels: > linux-image-4.16.0-2-powerpc64le (stock Debian kernel) > linux-image-4.16.18 > linux-image-4.17.4 > > My setup: > Debian buster (testing) > 1x POWER9 processor > LSI Megaraid 9361-16i (ALL disks are attached to this device). > 128GB ECC memory > 1x 10TB RAID1 volume (2 spinning disks) > 2x 2TB Samsung 860 pro SSD's > 2x 1TB Samsung 860 pro SSD's > (Note: all SSD's are in JBOD mode so I can access the individual disks > for TRIM, etc). > > I've formatted the entire 10TB RAID1 volume as a backing store. I've > tried using 2TB and 1TB SSD's as caching devices (all brand new). I've > even tried using a 1TB SSD has a caching device for a 2TB SSD. The > results have not differed. > > Thanks! Hi Cameron, Do you see anything suspicious from kernel message ? Or when the process hangs, can you have its stack trace from proc or by sysrq ? I don't touch any PPC64LE so far, and I assume it is same as x86-64 little endian, am I right ? Currently I have bug report that bcache does not work on big endian machines and I am working on the fix. But your machine is PPC64LE, maybe this is another separated issue. Thanks. Coly Li -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
