Re: [PATCHv5 0/4] mm/zpool: add common api for zswap to use zbud/zsmalloc

From: Dan Streetman
Date: Mon Jul 14 2014 - 14:11:21 EST


Andrew, any thoughts on this latest version of the patch set? Let me
know if I missed anything or you have any other suggestions.

Seth, did you get a chance to review this and/or test it out?



On Wed, Jul 2, 2014 at 5:45 PM, Dan Streetman <ddstreet@xxxxxxxx> 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. 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.
>
> ---
> Changes since v4 : https://lkml.org/lkml/2014/6/2/711
> -omit first patch, that removed gfp_t param from zpool_malloc()
> -move function doc from zpool.h to zpool.c
> -move module usage refcounting into patch that adds zpool
> -add extra refcounting to prevent driver unregister if in use
> -add doc clarifying concurrency usage
> -make zbud/zsmalloc zpool functions static
> -typo corrections
>
> 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 (4):
> 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
>
> include/linux/zbud.h | 2 +-
> include/linux/zpool.h | 106 +++++++++++++++
> mm/Kconfig | 43 +++---
> mm/Makefile | 1 +
> mm/zbud.c | 98 +++++++++++++-
> mm/zpool.c | 364 ++++++++++++++++++++++++++++++++++++++++++++++++++
> mm/zsmalloc.c | 84 ++++++++++++
> mm/zswap.c | 75 ++++++-----
> 8 files changed, 722 insertions(+), 51 deletions(-)
> create mode 100644 include/linux/zpool.h
> create mode 100644 mm/zpool.c
>
> --
> 1.8.3.1
>
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