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[PATCH v6] lightnvm: pblk

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  [PATCH v6] lightnvm: pblk "Javier González" <jg@lightnvm.io> - 2017-04-12 15:30 +0200
    Re: [PATCH v6] lightnvm: physical block device (pblk) target Matias Bjørling <mb@lightnvm.io> - 2017-04-12 23:00 +0200

#1622134 — [PATCH v6] lightnvm: pblk

Hi Matias,

A last spin to fix a regression that I introduced yesterday on v4. This
should be the one.

Thanks,
Javier

Changes since v5:
* Fix regression on the erase scheduler introduced on v4

Changes since v4:
* Rebase on top of Matias' for-4.12/core
* Fix type implicit conversions reported by sparse (reported by Bart Van
  Assche)
* Make error and debug statistics long atomic variables.

Changes since v3:
* Apply Bart's feedback [1]
* Implement dynamic L2P optimizations for > 32-bit physical media
  geometry (from Matias Bjørling)
* Fix memory leak on GC (Reported by Simon A. F. Lund)
* 8064 is a perfectly round number of lines :)

[1] https://lkml.org/lkml/2017/4/8/172

Changes since v2:
* Rebase on top of Matias' for-4.12/core
* Implement L2P scan recovery to recover L2P table in case of power
  failure.
* Re-design disk format to be more flexible in future versions (from
  Matias Bjørling)
* Implement per-instance uuid to allow correct recovery without
  forcing line erases (from Matias Bjørling)
* Re-design GC threading to have several GC readers and a single
  writer that places data on the write buffer. This allows to maximize
  the GC write buffer budget without having unnecessary GC writers
  competing for the write buffer lock.
* Simplify sysfs interface.
* Refactoring and several code improvements (together with Matias
  Bjørling)

Changes since v1:
* Rebase on top of Matias' for-4.12/core
* Move from per-LUN block allocation to a line model. This means that a
  whole lines across all LUNs is allocated at a time. Data is still
  stripped in a round-robin fashion at a page granurality.
* Implement new disk format scheme, where metadata is stored per line
  instead of per LUN. This allows for space optimizations.
* Improvements on GC workqueue management and victim selection.
* Implement sysfs interface to query pblk's operation and statistics.
* Implement a user - GC I/O rate-limiter
* Various bug fixes

Javier González (1):
  lightnvm: physical block device (pblk) target

 Documentation/lightnvm/pblk.txt  |   21 +
 drivers/lightnvm/Kconfig         |    9 +
 drivers/lightnvm/Makefile        |    5 +
 drivers/lightnvm/pblk-cache.c    |  114 +++
 drivers/lightnvm/pblk-core.c     | 1655 ++++++++++++++++++++++++++++++++++++++
 drivers/lightnvm/pblk-gc.c       |  555 +++++++++++++
 drivers/lightnvm/pblk-init.c     |  949 ++++++++++++++++++++++
 drivers/lightnvm/pblk-map.c      |  136 ++++
 drivers/lightnvm/pblk-rb.c       |  852 ++++++++++++++++++++
 drivers/lightnvm/pblk-read.c     |  529 ++++++++++++
 drivers/lightnvm/pblk-recovery.c |  998 +++++++++++++++++++++++
 drivers/lightnvm/pblk-rl.c       |  182 +++++
 drivers/lightnvm/pblk-sysfs.c    |  507 ++++++++++++
 drivers/lightnvm/pblk-write.c    |  411 ++++++++++
 drivers/lightnvm/pblk.h          | 1121 ++++++++++++++++++++++++++
 15 files changed, 8044 insertions(+)
 create mode 100644 Documentation/lightnvm/pblk.txt
 create mode 100644 drivers/lightnvm/pblk-cache.c
 create mode 100644 drivers/lightnvm/pblk-core.c
 create mode 100644 drivers/lightnvm/pblk-gc.c
 create mode 100644 drivers/lightnvm/pblk-init.c
 create mode 100644 drivers/lightnvm/pblk-map.c
 create mode 100644 drivers/lightnvm/pblk-rb.c
 create mode 100644 drivers/lightnvm/pblk-read.c
 create mode 100644 drivers/lightnvm/pblk-recovery.c
 create mode 100644 drivers/lightnvm/pblk-rl.c
 create mode 100644 drivers/lightnvm/pblk-sysfs.c
 create mode 100644 drivers/lightnvm/pblk-write.c
 create mode 100644 drivers/lightnvm/pblk.h

-- 
2.7.4

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#1622555 — Re: [PATCH v6] lightnvm: physical block device (pblk) target

On 04/12/2017 03:19 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>
> ---

Thanks Javier. Applied to 4.12, and replaced the v5 version.

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