On Thu, 25 Feb 2016, Scott McGillivray wrote: > No, doesn't' work either i'm afraid. Below is example of failing > silently with ram disk and succeeded with HDD as cache device. > > Tested with /lib/modules/4.5.0-rc3+/kernel/drivers/md/bcache/bcache.ko > > > with zram - doesn't work > ================= > > $ ls -al /sys/fs/bcache/ > total 0 > drwxr-xr-x 2 root root 0 Feb 25 13:42 . > drwxr-xr-x 9 root root 0 Feb 25 13:40 .. > --w------- 1 root root 4096 Feb 25 13:40 register > --w------- 1 root root 4096 Feb 25 13:40 register_quiet > > $ file /dev/zram0 > /dev/zram0: block special (250/0) > > $ fdisk -l /dev/zram0 > Disk /dev/zram0: 1 GiB, 1073741824 bytes, 262144 sectors > > $ make-bcache -C /dev/zram0 > UUID: 87e63981-7bd8-4cc3-93db-9ca275367c21 > Set UUID: 0bba8852-ad4f-41f4-bfa3-679a886a14ad > version: 0 > nbuckets: 2048 > block_size: 8 > bucket_size: 1024 > nr_in_set: 1 > nr_this_dev: 0 > first_bucket: 1 did you `echo /dev/zram0 > /sys/fs/bcache/register` and then `echo <CSET-UUID> > /sys/block/bcache0/bcache/attach` Not sure which UUID is the CSET UUID. Probably 0bba8852-ad4f-41f4-bfa3-679a886a14ad. See attaching bcache0 to a cache: https://www.kernel.org/doc/Documentation/bcache.txt -Eric > > > No errors, but nothing in dmesg and contents of /sys/fs/bcache/ remain > exactly the same... no UUID. Seems to just silently fail. > > > with HDD - works as expected. > ===================== > > $ fdisk -l /dev/sdf > Disk /dev/sdf: 1 GiB, 1073741824 bytes, 2097152 sectors > > $ file /dev/sdf > /dev/sdf: block special (8/80) > > $ make-bcache -C /dev/sdf > UUID: 3234c9e7-8186-4a7c-99a8-ae6a371c6f2c > Set UUID: 9a71faf7-a408-4f4d-906e-e5d67e43291f > version: 0 > nbuckets: 2048 > block_size: 1 > bucket_size: 1024 > nr_in_set: 1 > nr_this_dev: 0 > first_bucket: 1 > > $ ls -al /sys/fs/bcache/ > total 0 > drwxr-xr-x 3 root root 0 Feb 25 13:48 . > drwxr-xr-x 9 root root 0 Feb 25 13:40 .. > drwxr-xr-x 7 root root 0 Feb 25 13:48 9a71faf7-a408-4f4d-906e-e5d67e43291f > --w------- 1 root root 4096 Feb 25 13:40 register > --w------- 1 root root 4096 Feb 25 13:40 register_quiet > > $ dmesg > [ 714.168488] bcache: register_cache() registered cache device sdf > > > Thank you. > > On 24 February 2016 at 15:37, Eric Wheeler <lists@xxxxxxxxxxxx> wrote: > > > > On Tue, 16 Feb 2016, Scott McGillivray wrote: > > > >> Hello > >> > >> I am using Ubuntu 15.10 with latest nightly 4.5 kernel. Ubuntu creates > >> 16 RAM drives as /dev/ram0 - ram16 by default and i am trying to test > >> bcache and use one of these as a cache device. > >> > >> wipefs /dev/sdd > >> wipefs /dev/sdd -a > >> wipefs /dev/ram0 > >> wipefs /dev/ram0 -a > >> make-bcache -B /dev/sdd -C /dev/ram0 > > > > Does it work with /dev/zram0? You would prep it something like this: > > > > modprobe zram > > echo $((1024*1024*1024)) > /sys/block/zram0/disksize # 1GB > > make-bcache -C /dev/zram0 > > > > -Eric > > > > > > > >> At this point there were no errors output but there is also no UUID > >> entry in /sys/fs/bcache/. Only register and register_quiet. > >> > >> bache-super-show correctly prints info about both block and cache > >> devices when queried but when i try to manually attach the cache > >> device with echo cset.uuid > /sys/block/bcache0/bcache/attach i get no > >> error but in dmesg i see > >> > >> bcache: __cached_dev_store() Can't attach > >> 3f2521a6-2103-4e2e-a47d-cc56558e8f7d: cache set not found > >> > >> If i repeat this example but use another sd block device as cache then > >> it works OK. > >> > >> Can anyone confirm if it should be possible to use the ramdisk based > >> block device as a caching device with bcache ? > >> > >> I also tried to use a loop device as cache and that didn't work > >> either.. i got "kernel bug" in dmesg for > >> drivers/md/bcache/super.c:1812. RIP [] > >> cache_alloc.isra.21+0x646/0x670[bcache] > >> > >> Does bcache need the cache device to be a certain block type i.e sd 8 > >> ? Should i be able to use any block device from /proc/devices as a > >> cache device ? > >> > >> The kernel options used for ramdisk are: > >> > >> CONFIG_BLK_DEV_RAM=y > >> CONFIG_BLK_DEV_RAM_COUNT=16 > >> CONFIG_BLK_DEV_RAM_SIZE=65536 > >> CONFIG_BLK_DEV_RAM_DAX=y > >> > >> Thank you. > >> Scott > >> -- > >> 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 > >> > > > > > > > > -- > > Eric Wheeler, President eWheeler, Inc. dba Global Linux Security > > 888-LINUX26 (888-546-8926) Fax: 503-716-3878 PO Box 25107 > > www.GlobalLinuxSecurity.pro Linux since 1996! Portland, OR 97298 > > > -- > 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 > -- 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
