kernel.git/mm/frontswap.c, branch linux-3.8.y

frontswap: support exclusive gets if tmem backend is capable

2012-09-21T14:38:12Z

Tmem, as originally specified, assumes that "get" operations performed on persistent pools never flush the page of data out of tmem on a successful get, waiting instead for a flush operation. This is intended to mimic the model of a swap disk, where a disk read is non-destructive. Unlike a disk, however, freeing up the RAM can be valuable. Over the years that frontswap was in the review process, several reviewers (and notably Hugh Dickins in 2010) pointed out that this would result, at least temporarily, in two copies of the data in RAM: one (compressed for zcache) copy in tmem, and one copy in the swap cache. We wondered if this could be done differently, at least optionally. This patch allows tmem backends to instruct the frontswap code that this backend performs exclusive gets. Zcache2 already contains hooks to support this feature. Other backends are completely unaffected unless/until they are updated to support this feature. While it is not clear that exclusive gets are a performance win on all workloads at all times, this small patch allows for experimentation by backends. P.S. Let's not quibble about the naming of "get" vs "read" vs "load" etc. The naming is currently horribly inconsistent between cleancache and frontswap and existing tmem backends, so will need to be straightened out as a separate patch. "Get" is used by the tmem architecture spec, existing backends, and all documentation and presentation material so I am using it in this patch. Signed-off-by: Dan Magenheimer Signed-off-by: Konrad Rzeszutek Wilk

mm: frontswap: fix a wrong if condition in frontswap_shrink

2012-09-21T14:37:45Z

pages_to_unuse is set to 0 to unuse all frontswap pages But that doesn't happen since a wrong condition in frontswap_shrink cancel it. -v2: Add comment to explain return value of __frontswap_shrink, as suggested by Dan Carpenter, thanks Signed-off-by: Zhenzhong Duan Signed-off-by: Konrad Rzeszutek Wilk

mm/frontswap: fix uninit'ed variable warning

2012-08-13T19:41:30Z

Fixes uninitialized variable warning on 'type' in frontswap_shrink(). type is set before use by __frontswap_unuse_pages() called by __frontswap_shrink() called by frontswap_shrink() before use by try_to_unuse(). Signed-off-by: Seth Jennings Signed-off-by: Konrad Rzeszutek Wilk

mm/frontswap: cleanup doc and comment error

2012-07-23T15:16:20Z

Signed-off-by: Wanpeng Li Signed-off-by: Konrad Rzeszutek Wilk

mm: frontswap: remove unneeded headers

2012-07-23T15:16:13Z

Signed-off-by: Sasha Levin [v1: Rebased with tracing removed] Signed-off-by: Konrad Rzeszutek Wilk

mm: frontswap: split out function to clear a page out

2012-07-19T22:51:14Z

Signed-off-by: Sasha Levin Signed-off-by: Konrad Rzeszutek Wilk

mm: frontswap: remove unnecessary check during initialization

2012-06-11T19:32:08Z

The check whether frontswap is enabled or not is done in the API functions in the frontswap header, before they are passed to the internal double-underscored frontswap functions. Remove the check from __frontswap_init for consistency. Reviewed-by: Minchan Kim Signed-off-by: Sasha Levin Signed-off-by: Konrad Rzeszutek Wilk

mm: frontswap: make all branches of if statement in put page consistent

2012-06-11T19:31:55Z

Currently it has a complex structure where different things are compared at each branch. Simplify that and make both branches look similar. Reviewed-by: Minchan Kim Signed-off-by: Sasha Levin Signed-off-by: Konrad Rzeszutek Wilk

mm: frontswap: split frontswap_shrink further to simplify locking

2012-06-11T19:31:33Z

Split frontswap_shrink to simplify the locking in the original code. Also, assert that the function that was split still runs under the swap spinlock. Signed-off-by: Sasha Levin Signed-off-by: Konrad Rzeszutek Wilk

mm: frontswap: split out __frontswap_unuse_pages

2012-06-11T19:30:57Z

An attempt at making frontswap_shrink shorter and more readable. This patch splits out walking through the swap list to find an entry with enough pages to unuse. Also, assert that the internal __frontswap_unuse_pages is called under swap lock, since that part of code was previously directly happen inside the lock. Signed-off-by: Sasha Levin Signed-off-by: Konrad Rzeszutek Wilk