>>>>> "Jonathan" == Jonathan Derrick <jonathan.derrick@xxxxxxxxx> writes: > This introduces a percentage-flushing mechanism that works in-tandem to the > mdadm delay timer. The percentage argument is based on the number of chunks > dirty (rather than percentage), due to large drives requiring smaller and > smaller percentages (eg, 32TB drives-> 1% is 320GB). I've been reading and re-reading this and I still don't understand what you're saying here. You say you're adding a percentage based mechanism, but then you say it's based on chunk counts, not percentages. I think you need to clean this up and re-word it. Maybe you're trying to say that you only take a percentage of the available write bandwidth per second or something like that? > This set hopes to provide a way to make the bitmap flushing more consistent. It > was observed that a synchronous, random write qd1 workload, could make bitmap > writes easily become almost half of the I/O. And in similar workloads with > different timing, it was several minutes between bitmap updates. This is too > inconsistent to be reliable. > This first and second patches adds the flush_threshold parameter. The default > value of 0 defines the default behavior: unplugging immediately just as before. > With a flush-threshold value of 1, it becomes more consistent and paranoid, > flushing on nearly every I/O, leading to a 40% or greater situation. From What situation? Please be more clear here. > there, the flush_threshold can be defined higher for those situations where > power loss is rare and full resync can be tolerated. > The third patch converts the daemon worker to an actual timer. This makes it > more consistent and removes some ugly code. > Jonathan Derrick (3): > md/bitmap: Add chunk-threshold unplugging > md/bitmap: Add sysfs interface for flush threshold > md/bitmap: Convert daemon_work to proper timer > Documentation/admin-guide/md.rst | 5 ++ > drivers/md/md-bitmap.c | 98 +++++++++++++++++++++++++------- > drivers/md/md-bitmap.h | 4 +- > drivers/md/md.c | 9 ++- > drivers/md/md.h | 2 + > 5 files changed, 93 insertions(+), 25 deletions(-) > -- > 2.31.1
