On 6/4/21 8:35 PM, Santiago Castillo Oli wrote: > Hi Coli! > > > El 04/06/2021 a las 14:05, Coly Li escribió: >> What is the kernel version and where do you have the kernel ? And what >> is the workload on your machine ? > > I'm using debian 10 with default debian kernel (4.19.0-16-amd64) in > host and guests. > > For virtualization I'm using KVM. The kernel version is too old. I strongly suggest to use 5.3+ kernel, which most of obvious bugs were fixed. Then let's see what will happen. > > > There is a host, where bcache is running. The filesystem over bcache > device is ext4. In that filesystem there is only 9 qcow2 files user by > three VM guests. Two VM are running small nextcloud instances, another > one is running transmission (bittorrent) for feeding debian and other > distro iso files (30 files - 60 GiB approx.) > > >> Most of the read requests are missing, so they will read from backing >> device and refilled into cache device as used-and-clean data. Once there >> is no enough space to hold more read-cached data, garbage colleague may >> retire the used-and-clean data very fast and make available room for new >> refilling read data. The 19GB data might be existing data from last >> time gc. > > Is it possible to know GC last execution time? > See /sys/fs/bcache/<UUID>/internal/btree_gc_last_sec Coly Li
