mirror of
https://github.com/torvalds/linux
synced 2024-09-06 18:01:05 +00:00
mm: zswap: support exclusive loads
Commit 71024cb4a0
("frontswap: remove frontswap_tmem_exclusive_gets")
removed support for exclusive loads from frontswap as it was not used.
Bring back exclusive loads support to frontswap by adding an "exclusive"
output parameter to frontswap_ops->load.
On the zswap side, add a module parameter to enable/disable exclusive
loads, and a config option to control the boot default value. Refactor
zswap entry invalidation in zswap_frontswap_invalidate_page() into
zswap_invalidate_entry() to reuse it in zswap_frontswap_load() if
exclusive loads are enabled.
With exclusive loads, we avoid having two copies of the same page in
memory (compressed & uncompressed) after faulting it in from zswap. On
the other hand, if the page is to be reclaimed again without being
dirtied, it will be re-compressed. Compression is not usually slow, and a
page that was just faulted in is less likely to be reclaimed again soon.
Link: https://lkml.kernel.org/r/20230607195143.1473802-1-yosryahmed@google.com
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Suggested-by: Yu Zhao <yuzhao@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
parent
32b6a4a174
commit
b9c91c4341
|
@ -10,7 +10,7 @@
|
|||
struct frontswap_ops {
|
||||
void (*init)(unsigned); /* this swap type was just swapon'ed */
|
||||
int (*store)(unsigned, pgoff_t, struct page *); /* store a page */
|
||||
int (*load)(unsigned, pgoff_t, struct page *); /* load a page */
|
||||
int (*load)(unsigned, pgoff_t, struct page *, bool *); /* load a page */
|
||||
void (*invalidate_page)(unsigned, pgoff_t); /* page no longer needed */
|
||||
void (*invalidate_area)(unsigned); /* swap type just swapoff'ed */
|
||||
};
|
||||
|
|
16
mm/Kconfig
16
mm/Kconfig
|
@ -46,6 +46,22 @@ config ZSWAP_DEFAULT_ON
|
|||
The selection made here can be overridden by using the kernel
|
||||
command line 'zswap.enabled=' option.
|
||||
|
||||
config ZSWAP_EXCLUSIVE_LOADS_DEFAULT_ON
|
||||
bool "Invalidate zswap entries when pages are loaded"
|
||||
depends on ZSWAP
|
||||
help
|
||||
If selected, exclusive loads for zswap will be enabled at boot,
|
||||
otherwise it will be disabled.
|
||||
|
||||
If exclusive loads are enabled, when a page is loaded from zswap,
|
||||
the zswap entry is invalidated at once, as opposed to leaving it
|
||||
in zswap until the swap entry is freed.
|
||||
|
||||
This avoids having two copies of the same page in memory
|
||||
(compressed and uncompressed) after faulting in a page from zswap.
|
||||
The cost is that if the page was never dirtied and needs to be
|
||||
swapped out again, it will be re-compressed.
|
||||
|
||||
choice
|
||||
prompt "Default compressor"
|
||||
depends on ZSWAP
|
||||
|
|
|
@ -206,6 +206,7 @@ int __frontswap_load(struct page *page)
|
|||
int type = swp_type(entry);
|
||||
struct swap_info_struct *sis = swap_info[type];
|
||||
pgoff_t offset = swp_offset(entry);
|
||||
bool exclusive = false;
|
||||
|
||||
VM_BUG_ON(!frontswap_ops);
|
||||
VM_BUG_ON(!PageLocked(page));
|
||||
|
@ -215,9 +216,14 @@ int __frontswap_load(struct page *page)
|
|||
return -1;
|
||||
|
||||
/* Try loading from each implementation, until one succeeds. */
|
||||
ret = frontswap_ops->load(type, offset, page);
|
||||
if (ret == 0)
|
||||
ret = frontswap_ops->load(type, offset, page, &exclusive);
|
||||
if (ret == 0) {
|
||||
inc_frontswap_loads();
|
||||
if (exclusive) {
|
||||
SetPageDirty(page);
|
||||
__frontswap_clear(sis, offset);
|
||||
}
|
||||
}
|
||||
return ret;
|
||||
}
|
||||
|
||||
|
|
28
mm/zswap.c
28
mm/zswap.c
|
@ -138,6 +138,10 @@ static bool zswap_non_same_filled_pages_enabled = true;
|
|||
module_param_named(non_same_filled_pages_enabled, zswap_non_same_filled_pages_enabled,
|
||||
bool, 0644);
|
||||
|
||||
static bool zswap_exclusive_loads_enabled = IS_ENABLED(
|
||||
CONFIG_ZSWAP_EXCLUSIVE_LOADS_DEFAULT_ON);
|
||||
module_param_named(exclusive_loads, zswap_exclusive_loads_enabled, bool, 0644);
|
||||
|
||||
/*********************************
|
||||
* data structures
|
||||
**********************************/
|
||||
|
@ -1340,12 +1344,22 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
|
|||
goto reject;
|
||||
}
|
||||
|
||||
static void zswap_invalidate_entry(struct zswap_tree *tree,
|
||||
struct zswap_entry *entry)
|
||||
{
|
||||
/* remove from rbtree */
|
||||
zswap_rb_erase(&tree->rbroot, entry);
|
||||
|
||||
/* drop the initial reference from entry creation */
|
||||
zswap_entry_put(tree, entry);
|
||||
}
|
||||
|
||||
/*
|
||||
* returns 0 if the page was successfully decompressed
|
||||
* return -1 on entry not found or error
|
||||
*/
|
||||
static int zswap_frontswap_load(unsigned type, pgoff_t offset,
|
||||
struct page *page)
|
||||
struct page *page, bool *exclusive)
|
||||
{
|
||||
struct zswap_tree *tree = zswap_trees[type];
|
||||
struct zswap_entry *entry;
|
||||
|
@ -1415,6 +1429,10 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
|
|||
freeentry:
|
||||
spin_lock(&tree->lock);
|
||||
zswap_entry_put(tree, entry);
|
||||
if (!ret && zswap_exclusive_loads_enabled) {
|
||||
zswap_invalidate_entry(tree, entry);
|
||||
*exclusive = true;
|
||||
}
|
||||
spin_unlock(&tree->lock);
|
||||
|
||||
return ret;
|
||||
|
@ -1434,13 +1452,7 @@ static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset)
|
|||
spin_unlock(&tree->lock);
|
||||
return;
|
||||
}
|
||||
|
||||
/* remove from rbtree */
|
||||
zswap_rb_erase(&tree->rbroot, entry);
|
||||
|
||||
/* drop the initial reference from entry creation */
|
||||
zswap_entry_put(tree, entry);
|
||||
|
||||
zswap_invalidate_entry(tree, entry);
|
||||
spin_unlock(&tree->lock);
|
||||
}
|
||||
|
||||
|
|
Loading…
Reference in a new issue