kernel.git/drivers/lightnvm/pblk-sysfs.c, branch linux-4.16.y

lightnvm: pblk: use exact free block counter in RL

2018-01-05T15:50:12Z

Until now, pblk's rate-limiter has used a heuristic to reserve space for GC I/O given that the over-provision area was fixed. In preparation for allowing to define the over-provision area on target creation, define a dedicated free_block counter in the rate-limiter to track the number of blocks being used for user data. Signed-off-by: Javier González Signed-off-by: Hans Holmberg Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe

lightnvm: make geometry structures 2.0 ready

2018-01-05T15:50:12Z

Prepare for the 2.0 revision by adapting the geometry structures to coexist with the 1.2 revision. Signed-off-by: Matias Bjørling Reviewed-by: Javier González Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe

lightnvm: pblk: gc all lines in the pipeline before exit

2017-10-13T14:34:57Z

Finish garbage collect of the lines that are in the gc pipeline before exiting. Ensure that all lines already in in the pipeline goes through, from read to write. Do this by keeping track of how many lines are in the pipeline and waiting for that number to reach zero before exiting the gc reader task. Since we're adding a new gc line counter, change the name of inflight_gc to read_inflight_gc to make the distinction clear. Signed-off-by: Hans Holmberg Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe

lightnvm: pblk: remove unused return variable

2017-06-30T17:08:18Z

Remove unused variable. Signed-off-by: Javier González Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe

lightnvm: pblk: fail gracefully on irrec. error

2017-06-26T22:27:39Z

Due to user writes being decoupled from media writes because of the need of an intermediate write buffer, irrecoverable media write errors lead to pblk stalling; user writes fill up the buffer and end up in an infinite retry loop. In order to let user writes fail gracefully, it is necessary for pblk to keep track of its own internal state and prevent further writes from being placed into the write buffer. This patch implements a state machine to keep track of internal errors and, in case of failure, fail further user writes in an standard way. Depending on the type of error, pblk will do its best to persist buffered writes (which are already acknowledged) and close down on a graceful manner. This way, data might be recovered by re-instantiating pblk. Such state machine paves out the way for a state-based FTL log. Signed-off-by: Javier González Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe

lightnvm: pblk: redesign GC algorithm

2017-06-26T22:27:39Z

At the moment, in order to get enough read parallelism, we have recycled several lines at the same time. This approach has proven not to work well when reaching capacity, since we end up mixing valid data from all lines, thus not maintaining a sustainable free/recycled line ratio. The new design, relies on a two level workqueue mechanism. In the first level, we read the metadata for a number of lines based on the GC list they reside on (this is governed by the number of valid sectors in each line). In the second level, we recycle a single line at a time. Here, we issue reads in parallel, while a single GC write thread places data in the write buffer. This design allows to (i) only move data from one line at a time, thus maintaining a sane free/recycled ration and (ii) maintain the GC writer busy with recycled data. Signed-off-by: Javier González Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe

lightnvm: pblk: delete redundant buffer pointer

2017-06-26T22:27:39Z

After refactoring the metadata path, the backpointer controlling synced I/Os in a line becomes unnecessary; metadata is scheduled on the write thread, thus we know when the end of the line is reached and act on it directly. Signed-off-by: Javier González Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe

lightnvm: pblk: delete redundant debug line stat

2017-06-26T22:27:39Z

Remove a legacy variable that helped verifying the consistency of the run-time metadata for the free line list. With the new metadata layout, this check is no longer necessary. Signed-off-by: Javier González Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe

lightnvm: pblk: sched. metadata on write thread

2017-06-26T22:27:39Z

At the moment, line metadata is persisted on a separate work queue, that is kicked each time that a line is closed. The assumption when designing this was that freeing the write thread from creating a new write request was better than the potential impact of writes colliding on the media (user I/O and metadata I/O). Experimentation has proven that this assumption is wrong; collision can cause up to 25% of bandwidth and introduce long tail latencies on the write thread, which potentially cause user write threads to spend more time spinning to get a free entry on the write buffer. This patch moves the metadata logic to the write thread. When a line is closed, remaining metadata is written in memory and is placed on a metadata queue. The write thread then takes the metadata corresponding to the previous line, creates the write request and schedules it to minimize collisions on the media. Using this approach, we see that we can saturate the media's bandwidth, which helps reducing both write latencies and the spinning time for user writer threads. Signed-off-by: Javier González Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe

lightnvm: pblk: expose max sec per write on sysfs

2017-06-26T22:24:53Z

Allow to configure the number of maximum sectors per write command through sysfs. This makes it easier to tune write command sizes for different controller configurations. Signed-off-by: Javier González Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe