[PATCH v1 3/3] mm/shuffle: remove dynamic reconfiguration

David Hildenbrand
2020-06-16T11:52:40Z

Commit e900a918b098 ("mm: shuffle initial free memory to improve
memory-side-cache utilization") promised "autodetection of a
memory-side-cache (to be added in a follow-on patch)" over a year ago.

The original series included patches [1], however, they were dropped
during review [2] to be followed-up later.

Let's simplify for now and re-add when really (ever?) needed.

[1] https://lkml.kernel.org/r/154510700291.1941238.817190985966612531.stgit@dwillia2-desk3.amr.corp.intel.com/
[2] https://lkml.kernel.org/r/154690326478.676627.103843791978176914.stgit@dwillia2-desk3.amr.corp.intel.com/

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
mm/shuffle.c | 28 ++--------------------------
mm/shuffle.h | 17 -----------------
2 files changed, 2 insertions(+), 43 deletions(-)

diff --git a/mm/shuffle.c b/mm/shuffle.c
index 609c26aa57db0..702c0d5cf276c 100644
--- a/mm/shuffle.c
+++ b/mm/shuffle.c
@@ -10,33 +10,11 @@
#include "shuffle.h"

DEFINE_STATIC_KEY_FALSE(page_alloc_shuffle_key);
-static unsigned long shuffle_state __ro_after_init;
-
-/*
- * Depending on the architecture, module parameter parsing may run
- * before, or after the cache detection. SHUFFLE_FORCE_DISABLE prevents,
- * or reverts the enabling of the shuffle implementation. SHUFFLE_ENABLE
- * attempts to turn on the implementation, but aborts if it finds
- * SHUFFLE_FORCE_DISABLE already set.
- */
-__meminit void page_alloc_shuffle(enum mm_shuffle_ctl ctl)
-{
- if (ctl == SHUFFLE_FORCE_DISABLE)
- set_bit(SHUFFLE_FORCE_DISABLE, &shuffle_state);
-
- if (test_bit(SHUFFLE_FORCE_DISABLE, &shuffle_state)) {
- if (test_and_clear_bit(SHUFFLE_ENABLE, &shuffle_state))
- static_branch_disable(&page_alloc_shuffle_key);
- } else if (ctl == SHUFFLE_ENABLE
- && !test_and_set_bit(SHUFFLE_ENABLE, &shuffle_state))
- static_branch_enable(&page_alloc_shuffle_key);
-}

static bool shuffle_param;
static int shuffle_show(char *buffer, const struct kernel_param *kp)
{
- return sprintf(buffer, "%c\n", test_bit(SHUFFLE_ENABLE, &shuffle_state)
- ? 'Y' : 'N');
+ return sprintf(buffer, "%c\n", shuffle_param ? 'Y' : 'N');
}

static __meminit int shuffle_store(const char *val,
@@ -47,9 +25,7 @@ static __meminit int shuffle_store(const char *val,
if (rc < 0)
return rc;
if (shuffle_param)
- page_alloc_shuffle(SHUFFLE_ENABLE);
- else
- page_alloc_shuffle(SHUFFLE_FORCE_DISABLE);
+ static_branch_enable(&page_alloc_shuffle_key);
return 0;
}
module_param_call(shuffle, shuffle_store, shuffle_show, &shuffle_param, 0400);
diff --git a/mm/shuffle.h b/mm/shuffle.h
index 657e2b9ec38dd..5574cbd4611e3 100644
--- a/mm/shuffle.h
+++ b/mm/shuffle.h
@@ -4,23 +4,10 @@
#define _MM_SHUFFLE_H
#include <linux/jump_label.h>

-/*
- * SHUFFLE_ENABLE is called from the command line enabling path, or by
- * platform-firmware enabling that indicates the presence of a
- * direct-mapped memory-side-cache. SHUFFLE_FORCE_DISABLE is called from
- * the command line path and overrides any previous or future
- * SHUFFLE_ENABLE.
- */
-enum mm_shuffle_ctl {
- SHUFFLE_ENABLE,
- SHUFFLE_FORCE_DISABLE,
-};
-
#define SHUFFLE_ORDER (MAX_ORDER-1)

#ifdef CONFIG_SHUFFLE_PAGE_ALLOCATOR
DECLARE_STATIC_KEY_FALSE(page_alloc_shuffle_key);
-extern void page_alloc_shuffle(enum mm_shuffle_ctl ctl);
extern void __shuffle_free_memory(pg_data_t *pgdat);
extern bool shuffle_pick_tail(void);
static inline void shuffle_free_memory(pg_data_t *pgdat)
@@ -46,10 +33,6 @@ static inline void shuffle_free_memory(pg_data_t *pgdat)
{
}

-static inline void page_alloc_shuffle(enum mm_shuffle_ctl ctl)
-{
-}
-
static inline bool is_shuffle_order(int order)
{
return false;
--
2.26.2