Re: [PATCHv4 0/6] mm/zpool: add common api for zswap to use zbud/zsmalloc

[Seth Jennings]

On Mon, Jun 02, 2014 at 06:19:40PM -0400, Dan Streetman wrote:
> In order to allow zswap users to choose between zbud and zsmalloc for
> the compressed storage pool, this patch set adds a new api "zpool" that
> provides an interface to both zbud and zsmalloc.  Only minor changes
> to zbud's interface were needed.  This does not include implementing
> shrinking in zsmalloc, which will be sent separately.
> 
> I believe Seth originally was using zsmalloc for swap, but there were
> concerns about how significant the impact of shrinking zsmalloc would
> be when zswap had to start reclaiming pages.  That still may be an
> issue, but this at least allows users to choose themselves whether
> they want a lower-density or higher-density compressed storage medium.
> At least for situations where zswap reclaim is never or rarely reached,
> it probably makes sense to use the higher density of zsmalloc.
> 
> Note this patch set does not change zram to use zpool, although that
> change should be possible as well.

This looks good!  Much better than when we first started :) Thanks Dan.
I haven't had a chance to test it out yet so I'm going to wait to Ack it
until then, which might be as late as 6/16 due to a vacation and a
conference.

Thanks,
Seth

> 
> ---
> 
> Changes since v3 : https://lkml.org/lkml/2014/5/24/130
>   -In zpool_shrink() use # pages instead of # bytes
>   -Add reclaimed param to zpool_shrink() to indicate to caller
>    # pages actually reclaimed
>   -move module usage counting to zpool, from zbud/zsmalloc
>   -update zbud_zpool_shrink() to call zbud_reclaim_page() in a
>    loop until requested # pages have been reclaimed (or error)
> 
> Changes since v2 : https://lkml.org/lkml/2014/5/7/927
>   -Change zpool to use driver registration instead of hardcoding
>    implementations
>   -Add module use counting in zbud/zsmalloc
> 
> Changes since v1 https://lkml.org/lkml/2014/4/19/97
>  -remove zsmalloc shrinking
>  -change zbud size param type from unsigned int to size_t
>  -remove zpool fallback creation
>  -zswap manually falls back to zbud if specified type fails
> 
> 
> Dan Streetman (6):
>   mm/zbud: zbud_alloc() minor param change
>   mm/zbud: change zbud_alloc size type to size_t
>   mm/zpool: implement common zpool api to zbud/zsmalloc
>   mm/zpool: zbud/zsmalloc implement zpool
>   mm/zpool: update zswap to use zpool
>   mm/zpool: prevent zbud/zsmalloc from unloading when used
> 
>  include/linux/zbud.h  |   2 +-
>  include/linux/zpool.h | 224 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  mm/Kconfig            |  43 ++++++----
>  mm/Makefile           |   1 +
>  mm/zbud.c             | 123 +++++++++++++++++++++++----
>  mm/zpool.c            | 206 ++++++++++++++++++++++++++++++++++++++++++++++
>  mm/zsmalloc.c         |  83 +++++++++++++++++++
>  mm/zswap.c            |  76 ++++++++++-------
>  8 files changed, 694 insertions(+), 64 deletions(-)
>  create mode 100644 include/linux/zpool.h
>  create mode 100644 mm/zpool.c
> 
> -- 
> 1.8.3.1
> 
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