Re: [PATCHv2 00/15] dm-zoned: multi-device support

[Damien Le Moal <Damien.LeMoal@wdc.com>]

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On Wed, 2020-05-27 at 08:22 +0200, Hannes Reinecke wrote:
> Hi all,
> 
> here's the second version of my patchset to support multiple zoned
> drives with dm-zoned.
> This patchset:
> - Converts the zone array to using xarray for better scalability
> - Separates out shared structures into per-device structure
> - Enforce drive-locality for allocating and reclaiming zones
> - Lifts the restriction of 2 devices to handle an arbitrary number
>   of drives.
> 
> This gives me a near-perfect scalability by increasing the write
> speed from 150MB/s (for a cache and one zoned drive) to 300MB/s
> (for a cache and two zoned drives).

Finished running 3 tests (2 hours each) for single drive, Optane SSD +
single disk and Optane SSD + 2 disks. No problems detected.

See the attached file for a plot of the results. I also get near
perfect avergare performance scaling with the cache device from 185
MB/s with ssd+single disk to 367 MB/s with ssd+2 disks. And that is
more than 10 times higher than the legacy single drive setup at 34 MB/s
in average.

> 
> Changes to v1:
> - Include reviews from Damien
> - Reshuffle patches
> 
> Hannes Reinecke (15):
>   dm-zoned: add debugging message for reading superblocks
>   dm-zoned: secondary superblock must reside on the same devices than
>     primary superblock
>   dm-zoned: improve logging messages for reclaim
>   dm-zoned: add a 'reserved' zone flag
>   dm-zoned: convert to xarray
>   dm-zoned: temporary superblock for tertiary devices
>   dm-zoned: add device pointer to struct dm_zone
>   dm-zoned: add metadata pointer to struct dmz_dev
>   dm-zoned: allocate dm devices dynamically
>   dm-zoned: per-device reclaim
>   dm-zoned: move random and sequential zones into struct dmz_dev
>   dm-zoned: support arbitrary number of devices
>   dm-zoned: allocate zone by device index
>   dm-zoned: select reclaim zone based on device index
>   dm-zoned: prefer full zones for reclaim
> 
>  drivers/md/dm-zoned-metadata.c | 448 ++++++++++++++++++++++++-----------------
>  drivers/md/dm-zoned-reclaim.c  |  95 +++++----
>  drivers/md/dm-zoned-target.c   | 169 ++++++++++------
>  drivers/md/dm-zoned.h          |  77 ++++---
>  4 files changed, 481 insertions(+), 308 deletions(-)
> 

-- 
Damien Le Moal
Western Digital Research

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