Messages in this thread | | | Subject | Re: [PATCH v5] lightnvm: physical block device (pblk) target | From | Matias Bjørling <> | Date | Tue, 11 Apr 2017 16:41:46 +0200 |
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On 04/11/2017 04:31 PM, Javier González wrote: > This patch introduces pblk, a host-side translation layer for > Open-Channel SSDs to expose them like block devices. The translation > layer allows data placement decisions, and I/O scheduling to be > managed by the host, enabling users to optimize the SSD for their > specific workloads. > > An open-channel SSD has a set of LUNs (parallel units) and a > collection of blocks. Each block can be read in any order, but > writes must be sequential. Writes may also fail, and if a block > requires it, must also be reset before new writes can be > applied. > > To manage the constraints, pblk maintains a logical to > physical address (L2P) table, write cache, garbage > collection logic, recovery scheme, and logic to rate-limit > user I/Os versus garbage collection I/Os. > > The L2P table is fully-associative and manages sectors at a > 4KB granularity. Pblk stores the L2P table in two places, in > the out-of-band area of the media and on the last page of a > line. In the cause of a power failure, pblk will perform a > scan to recover the L2P table. > > The user data is organized into lines. A line is data > striped across blocks and LUNs. The lines enable the host to > reduce the amount of metadata to maintain besides the user > data and makes it easier to implement RAID or erasure coding > in the future. > > pblk implements multi-tenant support and can be instantiated > multiple times on the same drive. Each instance owns a > portion of the SSD - both regarding I/O bandwidth and > capacity - providing I/O isolation for each case. > > Finally, pblk also exposes a sysfs interface that allows > user-space to peek into the internals of pblk. The interface > is available at /dev/block/*/pblk/ where * is the block > device name exposed. > > This work also contains contributions from: > Matias Bjørling <matias@cnexlabs.com> > Simon A. F. Lund <slund@cnexlabs.com> > Young Tack Jin <youngtack.jin@gmail.com> > Huaicheng Li <huaicheng@cs.uchicago.edu> > > Signed-off-by: Javier González <javier@cnexlabs.com>
Awesome. Applied for 4.12.
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